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This is the final, and most important page.
Intense RF fields can cause heating of body tissue, but beyond this, there is no evidence that RF causes injury, remembering that this is non-ionising radiation. There are however speculative exposure limits. The basic one is the actual signal density, driven by power and antenna gain. The permitted level varies with frequency, being most strict in the VHF bands. Also, duty cycle comes into play, such as the typical 50% transmit time during a conversation.
At sensible power levels, such as 100 watts into a dipole at HF, the level is safe at a distance under a metre. This essentially means you just need to prevent someone leaning over the fence and touching the antenna.
Removed from the current pool, and primarily for "Field Day", and similar events in public areas, for ground mounted antennas, typically used at low HF, such as 80 metres, a timber fence or plastic mesh barrier is needed, primarily to prevent touching, but also to comply with EMR rules. Fibreglass rods for temporary electric fences, and light rope may work too, with signs. Metal fencing will interfere with the antenna's radiation pattern, and likely SWR.
A high gain, directional antenna, especially on VHF or UHF is where you may generate high field strengths, and the exam indicates you need to prevent the antenna pointing in the direction of a house where you would exceed this level, while it is occupied. (A mark on the dial of a rotator control is probably sufficient). Operating at reduced power in that direction is still permitted, although that may make something like EME more difficult.
Modulation is a significant factor in determining exposure. While AM, FM, and many digital modes have a density factor of 100%, a mode such as SSB may be at 20%, a little higher if heavily processed. The second factor is duty cycle: If you operate on a net with 3 other members, so only transmit one minute in four, the limiting factor becomes 1500 watts legal power, below the 2 kW this calculation gives.
How to assess this? One option is to perform an RF exposure evaluation in accordance with FCC OET Bulletin 65. It is available from their site as a PDF. Very simple, but conservative is a calculation using computer modelling, such as this one provided by the ARRL. Rounding out the three for the "All of the above" answer is "By measurement of field strength using calibrated equipment", meaning using a "A calibrated field strength meter with a calibrated antenna".
I believe distractors refer to the non-calibrated field strength meter in some SWR meters, of very limited use; and the screen based one a conflation with a spectrum analyser, which may actually be useful. The ARRL offers this useful QST article for free, which briefly discusses exemptions to this assessment.
The actual regulation is in Part 1, specifically § 1.1307. As medical devices and the like can be in close proximity to the body, this regulation applies to all transmitters with an average power above 1 mW, although there is also a table (also in the ARRL article) which provides an exemption at sensible power levels.
Part 97.13 (c)(1) says that "If the routine environmental evaluation indicates that the RF electromagnetic fields could exceed the limits contained in [section] 1.1310 of this chapter in accessible areas, the licensee must take action to prevent human exposure to such RF electromagnetic fields", then refers readers to OET 65. You can read s. 1.1310, which includes a table, on the ECFR system.
The real workflow would be to do the simple online assessment. If this passes, all good; if not, use OET 65 to make a more accurate assessment. If good, operate without restriction; if not limit power in the problematic direction, or limit power while using high duty-cycle modes in that direction. You might be able to run SSB at full power, but need to reduce power if using RTTY at a high duty cycle. For EME the problem may only exist while the antennas are aiming at the moon while is it very low in the sky.
If using an antenna indoors, the examiner indicates that you should "Make sure that MPE limits are not exceeded in occupied areas".
Given the nocebo effect, where if some internet echo-chamber tells a person of limited IQ and high suggestibility that something will harm them, they can feel unwell, or perceive a problem with their TV reception, it is an excellent idea to put up any visible HF antennas NOW, so that when Ken or Karen complains, you can point out that you have not transmitted using them, as you are not yet licensed for those bands. Plus you can listen to HF operations. Ditto for VHF+ if you have no licence at all. Another case of nocebo is the imagined effect of so-called infra-sound, supposedly generated by wind energy equipment. Maybe they'd prefer mildly radioactive coal soot and ash?
In HOAs flagpoles are great for transmitting, and a wire run around the top rail of a timber fence is great for, um, "receiving". Of course, many would say what Ken and Karen don't know won't hurt them. It is possible a new bipartisan bill may make it through the current chaos, reducing the influence of HOAs.
A removed question asked "What precaution should you take whenever you adjust or repair an antenna?", with the answer to "Turn off the transmitter and disconnect the feed line". This ensures that RF energy can't energise the antenna. I am sure you can work out appropriate procedure for your system.
Touching an energised antenna can cause an electric shock or painful burn, and perhaps cause a fall off a ladder, etc. Having a repeater transmit into a coax with no antenna may damage it.
"Mains" is a reference to utility supplied electricity; and "mains voltage" to any supply of a similar voltage. This can be provided by a generator or inverter. "Mains wiring" within equipment refers to parts live, or potentially live, at mains voltages. It is a British or Commonwealth term.
US power, in most cases, consists of a split phase connection, where the single phase is centre-tapped, so the 240 volts is grounded at the centre, and this point is also the neutral. Thus smaller items like supplies for 12 volt rigs, HT chargers, most lamps, and computers are connected from a single hot to neutral, receiving the 120 volt supply. Heavy duty devices, such as large linear amplifiers, and heating and clothes drying equipment* are connected between the hots, although control circuits and fans can be powered from a hot-to-neutral (120 volt) connection. Thus in these cases a 4 wire connection is used, the two hots, the neutral, and the safety ground (earth). Home or office EV charging also works best at 240 (or perhaps 277) volts. The US system has a vast number of different plugs, for different voltages and configurations, and different currents. NEMA plus non-NEMA types easily exceed 50 designs.
One issue with these plugs is what some call the "80/20 rule", being that for long term draw you should only draw 12 or 13 amps from a 15 amp socket, and 16 A from a 20 A one. This is why many heaters are 1560 watts instead of 1800.
Not just scary, but plain dangerous are adaptor cable and box assemblies designed to take power from two non-locking 5-15R outlets to power a device with an L14-20P locking plug, or other 240 volt outlet (typically 6- and 10- series). That is, the halves of split phase are combined to provide 240 volts. Clearly, if your toddler manages to pull one of the plugs it will have 120 volts from the other hot on its hot pin, via the load, along with a neutral and earth, all ready to improve the business of a child-sized coffin manufacturers, almost as effectively as RFK Jr's anti-vaxxing. Ditto anything else which amalgamates power using two or more plugs, unless it has interlocks to prevent a plug becoming live, such as a generator feed-in.
If you are setting up a dedicated area at home for a "shack" you might consider having some dedicated outlets installed, on their own circuit(s). Commercial grade, brand name, outlets are not too costly. If you are using a large amplifier, a dedicated high current 120 volts outlet (NEMA 5-20R), or 240 volt outlet (NEMA 6-15R), should power it. Or better, NEMA 14-15R and similar outlets have both hots, and the neutral, so components (fans, timers, transformers) of both 120 and 240 volts can be used within the amplifier.
If building a house I'd probably add a couple of outlets on the their own circuit in the halls, etc for often electrically noisy vacuum cleaners. These Hubbell ones look good, and you can colour-code them. Ditto something like a blue outlet in Oz.
Also, avoid any sort of USB power supply built into the outlet. I have a feeling they generate plenty of electrical noise and radio interference, and you can't unplug them if when they do!
NYC and parts of Miami are amongst exceptions to the above, where a 120/208 volt 3 phase system is used. This makes 240 volt heating elements, such as in ovens operate at lower power, and thus the oven becomes very slow to heat up. I wonder if there are 220 volt elements for Mexican 220 volts delta, which should work better.
Plugs should also be good quality, brand name items with a NEMA marking, such as "MEMA 5-15P". Hubbell, Leviton, Cooper, Molex, Volex, and Eaton are examples, ditto Pass & Seymour. Eaton have clear Hospital Grade ones which allow you to inspect connections visually.
Beware things like audiophile plugs, leads and sockets (the big dollar ones, or the Chinese copies), which often have metal bodies, potentially unearthed. Ditto anything shipped directly from China. I'd replace plug-pack / wall-wart supplies provided with handheld radios directly imported, with a locally approved one, and/or charge from the station supply at home, if the radio uses 12 volts. Some used USB-C or similar sources.
Mexico's NOM marking on things like chargers requires ongoing surveillance of the quality and safety of the product. There is no getting approval with all the EMC parts included, then building without them. Tequila, especially 100% Agave, has this mark beside a number.
*I usually dry my clothes using a combination of solar and wind energy on something which looks like a lot like a multiband VK2ABQ antenna. Yes, I think Fred Canton was inspired by a Hills Hoist rotary clothesline.
As an aside, NEMA 5-15 and 5-20 style connectors have been defined in IEC 60906-2:2011 as the global standard for 100 to 130 volt plugs and sockets for household and similar purposes. Most US products should operate on Mexican 127 volt power, although US filament lamps in a mobile home or desk / bedside lamp will suffer a shorter life.
In Australia, NZ and, and related areas of the Pacific, New Zealand's PDL, Clipsal, or HPM are the good options. Avoid Deta, and similar house brands. Basic / white Clipsal outlets are imported, but the dark blue ones I ordered were made to order here in Australia. Clipsal 25D has double pole switches, required for caravans and communications vans, etc. An electricians' supply shop can order in a "25-DB" in blue, or "25-RD", in red.
Australian-style "audiophile" power plugs with uninsulated pins are also unsafe, and any offered for sales in Australia or NZ should be reported to your state or territory, or national electrical authority. There is properly made audio gear, and there there are overpriced and often fraudulent products sold to the gullible, including (often excessively) chunky cables for power, interconnects, or speakers.
In US split phase connections, the two hots must be fused, but not the neutral, nor the earth. Likewise, in 120 volts cases only the hot is to be fused. The same rules apply to industrial voltages below. In three phase systems all phases must be fused, except Phase B in a corner-ground system.
Mythbusters made an error re fusing on the Christmas light story: If you place multiple fused circuits in parallel across an unfused source the individual fuses will not protect the supply or its wiring before them, if the current in each branch is less that the individual fuse rating. And throw out or rebuild 18 AWG (0.823 mm²) extension leads. 14 is the smallest which is safe, but 12 or 10 is better, especially for long runs, where voltage drop can become a problem. 16 AWG is the lightest for IEC (C13 or C14) leads. Smaller numbers (thicker cables) are fine, but not larger (thinner).
"Ground fault circuit interrupter (GFCI)" is American for "residual-current device (RCD)" or "residual-current circuit breaker (RCCB)", or "safety switch" for Australian consumers. The technically descriptive name is the earth leakage core balance relay, ELCBR, noting the R.
In these current carrying conductors pass through a small toroid. A winding on this toroid feeds a simple amplifier which triggers a breaker to remove power if the current is unbalanced.
Single phase, two wire ones (US 120 volt or Aussie 240 volt) ones work by comparing the current in the active with that in the neutral, and if there is a difference, this means current is flowing directly to ground, possibly via a person's body. For split phase with no neutral (US 240 volts) the current must be equal in both hots, or the device will trip. Even with a Neutral in the 240 volt system with, say a 10 amp load between hots, and a 1 amp load from hot to neutral the currents in the 3 wires going through the core balance.
Note that very old voltage-operated earth leakage circuit breaker (ELCB) only detect current flowing from the equipment chassis back to the switchboard via the earth wire. Thus, current flowing to ground elsewhere (including through an otherwise grounded person) will not trip the device.
The two big risks these do NOT protect against are: The first group is contact between Active and Neutral, between two phases in a 3 phase system within a 3 phase device, or between the two Hots of a US domestic 240 volt system within a 240 volt device. Contact between hots on circuits protected by two different GFCIs *should* trip both, as occurred when testing a voltage probe which included a buzzer as shown in my Technician Operations 2 page. It tripped both safety switches. The second is contact with dangerous AC or DC voltages beyond a transformer, such as in a valve / tube device, or high powered commercial audio amplifiers.
Some comments on dangerous faked earths used by house flippers, and the permitted method of upgrading 2 pin outlets: Fake Earths
Instead of wire size using square millimetres, the US uses American Wire Gauge, with large sizes being 0, or several zeros (or say 3/0, in place of 000), and increases normally by 2, in wire supplied by retailers, which indicates smaller sizes, with very fine "magnet" or coil-winding wire having the largest numbers. Informally, the terms "Brown & Sharpe" or "B&S", taken from the scale for sheet metal are used interchangeably, although this is not correct. The Numero sign, № is also used. Numbers between 8 to 16 relate mains wiring at home, 4 to 8 might be useful for DC wiring of transceivers. For mains power the primary consideration tends to be not having the wire overheat, and damage the insulation, or cause a fire. The wire size and fusing are linked. Factors, such as in ceiling insulation over wiring, or confining multiple conductors within a conduit or duct make de-rating necessary. More: Wikipedia: AWG. The British have gone metric, so have stopped using SWG, but 8 AWG is smaller than 8 SWG.
Off the paper, US the stranding standard uses letters. Info from several companies: IECW, AWC, AWG, and quite comprehensive one from LAPP. I have seen the rope style, where very fine (often 30 AWG) strands are formed into thin bundles, and these into heavier cable, used in the connection to motor bushes, where very high flexibility is required.
Current Ratings: AWG number 14 wire needs to be fused at 15 amps, according to the examiner. If this load is carried constantly, the wire would experience a fair degree of warming, especially if there is no airflow around it, or if it is in a hot roof space. To carry 20 amps no. 12 wire is required.
How to coalesce the values in your mind? Perhaps 14 and 15 are adjacent integers, and 12 and 20 both contain 2.
The said examiner however fails to mention that this only applies to copper wire. The US has a history of fitting aluminium (or "aluminum") wire in houses and commercial premises. Its higher resistivity means a greater cross-sectional area (lower AWG number) is needed for a certain current. Specialised termination methods are required to prevent fires. Because aluminium's expansion and contraction can loosen screw clamps, and because the oxide layer can increase resistance, these are subject to overheating joints, which can cause fires, with one example killing 165 people, and injuring over 200 more. Specially certified electricians must fit approved crimped transitions to copper pigtails, or use other approved techniques. The special purple wire-nuts are only for temporary repairs. East Germany also used aluminium, and Wago sells Alu-Plus Contact Paste to permit freshly scraped aluminium wire to be joined to copper wire using their connectors (although apparently not approved for the US).
In most other countries aluminium is used only in the street and high voltage distribution networks.
The examiner is also discussing cable with a rating of 60°C (140°F), in a situation where ambient is 30°C (86°F) or less, and three or less current carrying conductors are grouped. Other insulation types can tolerate greater temperatures. See: NEC Table 310.15(B)(16). Noting that more and more areas are having roof space temperatures exceed the figure above, other cases are discussed here: Notes on Table 310.15(B)(2). Appropriate ventilation may help. Also, covering wiring with thermal insulation material, can be problematic.
Most other countries specify wire in square millimetres. Examples of "building wire" are 1, 1.5, 2.5, 4, 6, and 10 mm². Australia generally uses coarse stranded conductors (Class 2), some use single core (Class 1), which can break if flexed too often, well before the 7 strand ones. Flex (Class 5, many strands per conductor) includes 0.75, 1.0, 1.5, and 2.5 mm² with 4 or 6 mm² for cooking equipment, if a plug is used. In both cases there are larger cables for industrial uses. They are defined in DIN VDE 0295 and IEC 60228, as discussed at Wikipedia: IEC 60228. Class 6 has even finer strands, useful in things such as industrial robots, where bending and twisting occurs frequently. Test leads have similar flexibility. There are additional columns, with Column 2 contains wire with intermediate stranding, such as 19 strands for 2.5 mm², rather than 50.
A bit off topic, but useful: For 12 volt systems we are normally selecting conductors for low voltage drop, so the conductor is often thicker than needed for safety. You might fuse the beginning of the cable for its protection, maybe 35 amps, then at the other end, fuse for the radio (maybe 20 or 25 amps). If you have a larger multi-band, multi-mode Amateur rig, and say a 2 metre / 70 cm FM only, DMR, a CB, or a type-approved emergency communications group radio on the same cable, fuse each one individually so one does not take all radios out of action. There is discussion about fusing the negative run to the radio, and whether this connection should be to the body end of the grounding strap, or on the battery. A 45 amp fuse in the negative may be useful, especially if connecting to the battery negative, in case the negative strap comes lose, and the starting current attempts to flow via your radio wiring, and the antenna base.
CB may be the "lowest common denominator" for inter-agency communications during emergencies, and useful for things like moving traffic around crash sites. For South Pacific folks UHF CB channels can be programmed into type approved radios (Tait, Vertex Standard, Motorola, etc).
This is termed programmed fusing, meaning the fuse in the cabin protecting the radio should blow, rather that the one in at the battery, which should only blow if the insulation of the cable is melted or otherwise damaged. This is similar to the idea that the fuse in a low current device in a fuse blows, rather that tripping the breaker the panel; in the UK the fuse in the plug opens to protect the flex, and if something catastrophic happens the 32 amp fuse or breaker opens; perhaps an unfused adaptor bought overseas was used, and a large 120 volt load connected, drawing excessive current, at least after the flex melts and shorts. Or perhaps it burns at 30 amps, and so burns your B&B down.
At 12 volts there is no reason you can't use 100 mm or so of wire complying with ratings from a supply, then transitioning to a heavier cable running to equipment. Things like 45 amp PowerPoles have limited capacity to hold wires as thick as we may like to use, so transitioning using yellow crimp butt terminals can help.
120 volts runs into voltage drop issues faster than 230 volts, and if you are using a generator which you place some distance from the operating point due to its audible noise, and perhaps RF noise, you should use a heavy cable, such as 10 AWG. Aussies can use a building site lead, 1.5 mm² but with 10 amp connectors; or 15 amp a caravan lead. Excessively long leads, especially if lighter, will have so much resistance that they will not reliably trip a breaker of say 20 amps.
I certainly would not use unstranded wire in a communications trailer, converted minibus, or similar vehicle, at either 12 or 24 volts, or mains voltages, lest it fracture from vibrations.
Be aware that some auto parts and marine shops in Australia use an overall diameter in millimetres, including insulation, rather than square millimetres, and/or AWG. Not super, and not cheap. Others use "B&S" unlawfully.
LAPP sells certified road transport cables, termed TRUCK, along with TRAIN and SOLAR products. The latter includes sheathed 4 mm² and 6 mm² 2 wire cables (2X4 and 2X6). They also have rugged and/or low smoke European harmonised and UL listed mains cables.
Something coming from the likes of Temu is Copper Clad Aluminium wire. Often multi-stranded, this has an unusual, "dead" feel. I expect even if soldered to a PCB it will fatigue and break if flexed a few times. This should be avoided, as I am sure things like expansion-contraction cycles can loosen screws.
Before you buy something from Temu, Aliexpress, or the big river company (expensive Temu) consider whether it could cause serious damage, injury, or worse; or failure of communications during a critical event, if it fails.
For field day events, or after disasters, it may be necessary to run station equipment from a small petrol (gasoline), or other generator. The exam focuses on the carbon-monoxide (CO) hazard from these. CO is an odourless, toxic gas which interferes with your blood carrying oxygen to your organs, with symptoms similar to a cold or influenza, minus the throat pain. Thus generators must be placed in areas which are well ventilated. An earth stake connected to the frame is a good idea. You may want to have it some distance from the station, to limit the audio and electrical noise from the generator. Especially at 120 volts, you may need to use a cable heavier than strictly necessary, to reduce the voltage drop.
These will eventually be banned in California, and while the goal may be something like a large, higher voltage lithium battery pack running an inverter, and charged by high voltage solar panels, the regulation does not ban diesel (compression ignition) engines, so that is probably where things will end up.
If you connect a generator to your house, club rooms, EOC, or similar, you must either have interlocked breakers, or otherwise disconnect the incoming connection, to ensure this power cannot go into the street wiring, so you don't "Electrolux" the line workers. A cable to your 'fridge and freezer, a few lights, and plug-in cooking equipment, connected when needed, may be a safer option, as long as it is not a trip hazard.
Absolutely DO NOT use a cable with two plugs on it, as these can do things like put power into the overhead wiring killing electrical workers*; or kill any child who plays it. "Death lead" is an appropriate name. It can potentially also damage the generator when power comes back on.
* US distribution means that your house may be the only one connected to a transformer, and 120 volts at its (usual) secondary will put thousands of volts into the distribution voltage lines, which may be in the process of being restored. The same can apply in rural areas in Australia.
Given the flammability of petrol / gasoline care should be taken during refuelling. Approved fuel containers should be used. Fuels are non-conductive, meaning static can build up. Tanks should be placed on the ground when filling from a bowser; or for large drums on a ute or pickup, the earth bonding cable, provided on a reel at rural fuel retailers, used. Having an appropriate extinguisher nearby is wise. Diesel is less likely to catch fire from a spark, but can burn if soaked into rags, or similar.
An alternative is to use the "V2L", or vehicle to load, function available in Chinese built Electric vehicles. It will power refrigerators, freezers, and medical equipment, kettles or jugs, and plug-in cooktops, although likely not all at once.
"V2H", vehicle to house is an integrated system which can power appliances through the house's wiring. Likewise, a well designed solar plus home battery systems can also power selected loads during an outage. "V2G", or vehicle to grid is supported by carious vehicles, but the grid part is still subject to bureaucratic faffing-about in many areas. During a high demand period, or when worn out coal (or nuclear) plants trip or scram, the grid can place a bid with the smarts in your car to buy power from it. You can set it up to allow this or not, depending on planned travel, and the like.
V2L is also great for powering radio equipment for field day, including amplifiers. BYD and MG cars in 220 - 240 volt markets can provide up to 16 amps at around 240 volts.
The NEC is the National Electrical Code, and various versions have been ratified at the state or county level, making them the regulations applying to domestic and commercial power installations, including Amateur Radio shacks. Portable buildings, travel trailers, caravans, RVs, and (presumably) communications vans also need to comply.
The NEC is written by the National Fire Protection Association.
Your station needs as extensive a grounding system as is practical. This consists of ground rods, and bonding to the power earth, and water pipes, and other metal. Shields of coax need to be grounded, and a lightning arrester should be placed at this point. Grounding metal roofs is a very good idea too. As you want to keep energy outside your house, etc, you need these to be external.
Towers need extensive grounding. Six runs, each with seven rods is the sort of thing a 30 metre (100 ft) tower needs. Rods should be at least 1.8 to 2 metres apart.
Your TV antenna coax should also be grounded and bonded to the system.
Multimeters, and the like must be used with care on mains, or other voltages above around 50 volts; and with high current circuits, or where a large "fault current" is possible, such as larger batteries. This includes following voltage ratings and meter classes.
For circuit development, and trouble-shooting lower current DC equipment, a smaller power supplier, rather than the large station supply, can be a good idea. This unit from Element 14 includes a current limiting function: TENMA 72-2690. This is cute, but expensive: TENMA 72-2660, a multimeter sized unit with voltage and current regulation modes, and inbuilt voltage and current metering. A used 13.8 volt, ~3 amp "CB supply" is an affordable alternative. You can add a couple of 78-series regulators for logic and other circuits (internally or externally). You could cascade a 7809, and a 7805. An old laptop supplying a box with an LM317 or similar variable regulator might work too.
Current transformers, as used in some tong testers, and larger fixed installations are capable of developing lethal voltages across their terminals if these are not correctly terminated. If it steps current down, then it must step voltage up.
Phillips screwdrivers were designed to "cam out", as they were used with powered driver to build high volume, lowest possible production cost cars like the Model-T, so once torque was adequate the operator would know, and there is less chance or breaking the screw or stripping the thread. The JIS Type-S or JIS B 1012 driver, along with Pozidriv, Supadriv, and ISO 8764 are designed not to cam out. Square "Robertson" drives often fit the combination slots of North American power sockets and switches (weird combination drivers may also be available). Special drivers are available which best fit combination Pozi-slot or Phillips-slot heads on many electrical fittings in Australia and NZ, with the downside you need to look closely to confirm orientation.
Safety glasses are a good idea for soldering and any mechanical work, including working on antennas, including as ground crew; a dropped nut can hit a tower part, and shoot outward rapidly. Glasses relating to firearms may be suitable, especially tinted ones, when working outdoors. You can also specify safety lenses in spectacles. Hi-viz lime-yellow is a great choice of colour for a helmet (it makes it easier for the climber to see where you are), especially one with with a sun visor. Ditto wearing sun-screen and lip protection while outside, often looking upwards.
A few thoughts beyond the exam follow. You can skip to the questions, although comments on dangerous power adaptors might be worth reading.
A model used in commercial aviation is the "Swiss Cheese Model". Suppose you place several slices of Swiss cheese (or Jarlsberg) hanging up in a row, and then try shining a laser pointer through them, or poking them with a blunt knitting needle. Occasionally you will penetrate the first layer, and hit the second, very occasionally it will go through the second to the third, and on rare occasions you get all the way through, symbolising a major incident. In our case this represents things like correctly sized wire, reliable terminals, effective insulation, fusing, reliable earthing, and an RCD / GFCI.
These countries, along with Kiribati, Fiji, Nauru, Vanuatu, Tuvalu, Tonga, Cook Islands, Samoa, American Samoa (in part, at 120 volts), Timor-Leste (in part) use Australian style outlets and plugs. The standard is AS/NZS 3112. 10 and 15 amps plugs following the 2000 or later editions of this compulsory standard must have around 8.5 mm of insulation around the base of the active and neutral pins.
China uses a plug supposedly based on the Australian one, or perhaps in its US predecessor. It however has a few significant differences, including no insulation on the power carrying pins, and these pins being a millimetre or so longer. It is used with the earth pin upper-most, as the US version was. These longer, uninsulated pins can become live with a gap between the plug and socket faces large enough for a child's finger to contact the pin. Uzbekistan and Tajikistan have likely followed the Chinese model.
Note that the danger does not come from a lack of quality, but the physical dimensions. Australian specification products made under contract to western companies should be fine, assuming they have good in-country supervision, while Chinese ones should be OK to use in China. Australian ones work in China, although I just used a 'phone charger, not a hair dryer, or something else with a large draw; I assume the contact would be adequate.
With a failure of the previous conservative government in Australia to maintain good relationships with its neighbours, China's influence in several Pacific and India Ocean countries has grown. I am unsure if that includes providing equipment with domestic Chinese power plugs as aid.
Several countries in South and America use similar plugs, but I am unsure of the exact details, except that they are NOT insulated, and Active and Neutral are typically swapped.
Staying off the exam, for Americans travelling, several countries may have outlets (perhaps used in addition to others) similar to NEMA 1-15R, perhaps unpolarised, but with 220 to 240 volts on them. This includes Italy, China, Thailand, Peru (also 5-15R); and in industrial settings, or very old buildings, Australia. I've seen maybe three here in my life. A few countries may have both 110 and 220 volts.
Almost every other standard wall outlet around the world has between 220 and 240 volts on it, often termed 230 volts.
The UK uses the BS 1363 socket and plug. Sockets are on a Ring Main with a 32 amp fuse or breaker, with a fuse in the plug to protect the connected flex (flexible cable). Adaptors must comply with 'BS 8546: 2016 - Travel adaptors compatible with UK plug and socket system', which requires a fuse complying with BS 1362 on the plug side. Buy it in the UK, as many countries certify adaptors which will burn down your Hotel or B&B if something goes wrong, or at the very least allow the destruction a US hairdryer, instead of have it blow the adaptor's fuse. The power carrying pins must have insulation near the plug body, but NOT the earth pin (a plastic pin (ISOD) on a double-insulated product is OK, as it is needed to open the shutters for double-insulated items). Shaver outlets accept US plugs, but are limited to 20 VA. Ireland, Crown dependencies, Malta, Cyprus, BOTs, and many ex-colonies use this too. Other ex-colonies use BS 546 connectors with round pins, but those in the UK might be best left alone, as they can be used for remotely switched or dimmed standard lamps.
Most of the remainder of Europe uses connectors in the CEE 7 system, with 2 round pins carrying the power. France's CEE 7/5 sockets are supposedly polarised, but connections vary; earthing is via a pin protruding from the recessed socket. Germany's CEE 7/3 Schuko outlet is short for Schutzkontakt, meaning "protective contact", and uses a "scraping earth", via clips in the sides of the socket (also recessed) and plug. These block the perfectly round French 7/6. German-style connectors not polarised, but this initially did not matter, as the two pins connected to two phases of a 3 phase system, while lights were 127 volts between a phase and neutral. While one pin is now phase, the other neutral in most of Europe, much of Norway, and part of Germany still place both power and lighting loads between two phases. Italy once used the same 127/220 volt concept, with luce and forza. French 7/6 plugs and German 7/4 are the earthed plug, with 7/7 compatible with both, having both an earthing orifice, and side-mounted earthing contacts. CEE 7/16 Alternative II "Europlug" is a thin (14 mm) plug compatible with many a wide range of sockets across Europe, Israel, South Africa, and Brazil (may be 127 volts), in Korea, Timor Leste (many), Indonesia, and many in China and Thailand. Denmark has its own "Smiling Face" design. All sockets above accept Europlugs.
Neither British / Irish, nor European plugs should be CE marked, nor UKCA or UKNI marked. Marking should be by an agency appointed by the country the equipment is marketed from or sold in. See: Certification Marks. Chargers however should carry the CE mark, and/or the mostly failed UKCA one.
Much of the former Soviet Union uses GOST standard ones compatible with CEE 7 types, with the note that earthing may not be available. Many Chinese wall sockets also accept Europlugs, and it appears higher current plugs, with no earthing. Israel (4X) uses a specific socket, SI 32, for earthed equipment.
There are several incompatible plugs with a active and neutral at the European 19 mm spacing, but with an earth pin offset from the central line. South Africa's SANS 144-2 units fully comply with IEC 60906-1, including shutters; Brazil's NBR 14136 ones fail to comply in several ways, even if both have a 3mm offset. Both have a 17 mm wide recess. Switzerland has a 5 mm offset, and a 20 mm wide recess. Italy's are exactly in line, although, there is a widespread move to Schuko. Again, these accept Europlugs, the irregular six-sided recess preventing larger CEE 7 plugs fitting. Brazilian outlets can be wired for 220 or 127 volts, or apparently there may be a switch.
The aforementioned IEC 60906-1:2009 provides a compact plug for use at 200 V to 250 V a.c, at 16 amps.
France includes various islands, termed "overseas collectivities" or "overseas departments" using CEE 7/5 outlets; sometimes with the unearthed CEE 7/1 socket as well, which accepts many plugs, without providing an earth. 7/1 often has only a shallow recess (my Grandparent's house in Norway included some of these too, in the 1980s). New Caledonia (a Sui generis collectivity) uses CEE 7/5.
Australia, and most other parts of the Pacific once under British colonisation use AS/NZS 3112 connectors. These have the earth pin at the bottom, with insulation on the power pins. For adaptors the earth hole on the US side should be upper-most. Don't use crappy Chinese made "FOR EXPORT ONLY" ones, occasionally sold illegally in convenience and 'phone cover shops in Australia, and elsewhere. They should be marked with an SAA number, even if the ones so marked for UK use can be deadly, if unfused. Adaptors which allow and Australian plug to connect to a US outlet must have the earth down on US outlets with the earth at the top, and earth slot up when the US earth is at the bottom.
Almost every adaptor at an online retailer / marketplace named for a large river in South America is PRIMEd to kill you. And then the NYT is telling people to buy dangerous ones from that marketplace, as their "top pick". A major danger is that either one pin can be plugged into the hot / phase / active hole, while the other hangs out to kill you, or even that the earth pin on your device can be plugged into the live pin, making its case live! And kids can insert metal pens, etc. Another hazards is hot - neutral interchange on badly designed adaptors, including the FOR EXPORT ONLY ones above, when a US plug is inserted.
If you notice a company selling them as accessories to their products, contact them, as some will take on board comments regarding them.
While a NEMA 6-15P to CEE 7, Australian, or British style socket would be great for running equipment at 240 volts, ones without dangerous multi-type outlets are rare. In these cases making a suitable cable may be safer. 6-15P to IEC cables are also available, in several lengths: Stay Online 6-15 to IEC C13
Types designed to provide a selection of plug types via a flip-out or slide out mechanism have been known to present mains voltage to pins not plugged into the outlet or extension lead socket!
For equipment with an IEC 60320 power inlet (see below), buying a good quality cable locally is an option, ditto a good quality local 'phone charger. However, Officeworks in Australia seems to have a lot a recalls on chargers with failing ultrasonic welds between the plastic part with the plug pins, and the rest of the charger body, allowing contact with live metal, and an increased workload for the coroner.
While mostly appearing safe, adaptors which plug into a 6-15R outlet to allow a 5-15P plug to be used need to be used with caution. These apply the second hot to the neutral pin of the 120 volt plugs. The main use would be to use dual-voltage gear in commercial premises, but could clearly damage 120 volt-only equipment. The reverse is also available.
It is possible that your club is offered access to space in the roof-top plant-room of a large building, for a repeater, access point, etc. It is possible the only power will be at an industrial voltage. In the US this is often 277 volts, which is the star or wye voltage of 480 volts delta system. In Canada it may be 347 volts, which is the wye of 600 volts systems.
There are two possible solutions. One is to use a transformer to provide 120 volts to run equipment. From 277 volts another may be to use a power supply or charger marked as 277 volts, or for a voltage range up to 305 volts.
Single phase outlets are in the NEMA 7-15R format (crowsfoot with a round or U-shaped earth), a locking L7 series one, or an IEC 60309 P+N+E 150° / 5h connector in grey. 347 volts uses NEMA 24 series or L24 series. While 277 volts is not significantly greater than the domestic voltage in much of the world, you should use full safety measures, such as checking your test-lamp or voltage detector on a live circuit, confirming the circuit to be worked on is dead, then re-checking the detector is good. Although you may not need to do anything other than plug your supply in.
Another of the many possible supply formats is split phase, or high-leg delta with double the usual voltage(s). In this case the 240 volts hot to neutral may be used to power may chargers or power supplies capable of accepting 240 volts; most PCs, mini PCs, and RaspberryPi supplies eat 240 volts as well. Presumably a 6-series plug (or similar) is needed, or a IEC 60309, probably in blue. Another possibility is Corner Grounded Delta or "Grounded B", as the B phase is grounded. If you have a 240 volt device you may be able to use this directly, otherwise, a transformer will be needed, ditto for 480 volt corner grounded supply.
There are also a number of California Standard bayonet connectors, predating the NEMA system; and older colour-coded Hubbell "Variload Twist-Lock". Use for these include 120 volts (yellow), and 120 / 240 volt (orange), so it is possible all you need is an appropriate cable. There are also US "Pin and Sleeve"connectors, noting that this term can also be applied to IEC 60309.
If in doubt discuss this with the building's logistics / building services person, and/or a electrician with commercial experience.
Note that in 230 volt countries generally have domestic and commercial power systems are very similar, except perhaps needing an industrial connector; IEC 60309 connectors are reasonably affordable. Brits often call these Commando plugs, for a genericised MK brand name. Old standard numbers for these are IEC 309, CEE 17, and EN 60309.
In the Pacific region Clipsal 56 series outlets are often in harsh commercial settings. For those containing a standard socket, use a compatible hard plastic plug with retention ring, as having the cable exit of a domestic lead crushed by the sprung cover is rather dodgy. This series includes round pin single and three phase outlets, in the latter case only 5 pin ones include a neutral. You can break out a single phase using a 5 pin plug. There are several metal clad cousins, some branded Wilco.
A 400 volt delta system without neutral is about the only time you won't get 230 volts, and may either need a new circuit (or perhaps just a neutral) run, or a 400 to 230 volt transformer. There is a rare 690 volt delta system too, which may provide 400 volts star.
Instead of a power cable protruding from the device, many use an panel mounted "plug", to which a line mounted socket is plugged. Modern equipment often uses the IEC 60320 series, be these figure-8 ones on cassette decks and the supplies for mini laptops C8, accepting C7 connectors; Mickey-Mouse / Coverleaf one for full-sized laptops, C6 accepting C5; or the bevelled rectangular ones on desktops, monitors, projectors, and Yaesu FT-757 external power supplies C14 accepting C13 (and C15 high temperature "jug plugs"). C20 accepts C19 in 16 amp applications. Some PCs have a typically switched C13 outlet which accepts a shrouded C14 plug for monitors; while C19 outputs from big UPSs accept C20 plugs. There are C18 / C17, and C24 / C23 without earth, which the inlets the earthed line sockets, but not vis-a-versa; and further high temperature versions.
Where possible with the two-pin type, use a cable with a sheath, rather than one with single-insulated figure-8 wire.
C14 inlets especially may be integrated with a fuse, perhaps over-voltage protection and/or noise filtering, and maybe a power switch. In some cases voltage selection may be used, either configuring transformer connections (potentially with multiple taps on projectors using a low voltage lamp), or altering the configuration of a rectifier on a PC supply. For most transformer inputs with two options, the 120 volt primaries are either placed in series for 230 volt class countries, or in parallel for 120 volt ones.
powerCon [sic] is an inlet if blue, to which a blue cable mounted connector is connected to supply power to stage equipment. The grey outlet can be used to daisy-chain power using a grey plug. The initial supplier is Neutrik, with Amphenol as a second supplier. Listing at Altronics. They twist to lock, requiring the tab to be pulled back to release via reversing the twist. Insul-Lock is the compatible Hubbell alternative. You should not connect or disconnect these under load. Note also they can be used with 120 volt, 230 volt, and North American 240 volt power. It was developed from the mostly black speakON [sic] fully insulated multi-pole speaker connectors.
ITT Cannon used to make a power version of its XLR connector (often used for microphones), called the XLR-LNE. Very compact, they were used on SAGEM Teletype machines, used in the Telex service. They were also used for broadcast equipment by the Australian Broadcasting Commission / Corporation (ABC). As pins are well recessed, and sleeves well shrouded, either can safely be live; with both forms being available in panel and cable-mount; and there being no standard, SAGEM and the ABC used opposite connection formats, meaning a Telex lead from the office or Newsroom, and a lead from Production could make a death lead if plugged together. Wikipedia: Obsolete XLRs. Some now vintage video monitors (typically B&W) used Cannon EP-4, also used for speakers, as a power inlet. As there are 4 identical pins in a square in the line connector, extreme care is needed when constructing a power lead for them, if you do not replace the inlet. Continuity check the wall plug's earth pin to the chassis, and for no conduction from the power pins to the case. Cinch and Cheatcord are others.
Before HP was a printer ink merchant, Hewlett Packard manufactured excellent test equipment, and pioneered electronic calculators. Predating the IEC types above an oval shaped inlet was used on their large nixitube voltmeters (and on early on Friden calculators), accepting the PH-163 (etc) connector, as fitted to the Belden 17952 cordset. Unfortunately, UL and CSA wrote a standard with Line and Neutral swapped to this version, requiring the the Belden 17280 cordset. This also caused a shock hazard while servicing various nuclear contamination detection equipment. See: Conectors on Madrona Grove (early calculator site) and Switchcraft inlets for Beldon line connectors.
A usually recessed NEMA 5-15 plug can be used as a power input. In the lighting industry they have space for a full sided extension lead socket, and are called an Edison Plug, PBG (Parallel Blade with Ground), U-ground, or Hubbell. More broadly these are straight blade . A very tight version is also shown on the calculator page above.
Bulgin and Belling Lee make small round appliance inlet and outlet connectors, typically rated at 2, 3, 5, 6, or 10 amps. Older cable mounted sockets were brittle Bakelite.
There are a huge number of plug and sockets on the Digital Museum of Plugs and Sockets, including appliance couplers.
These are actual questions from the General exam pool.
G0A01
What is one way that RF energy can affect human body tissue?
A. It heats body tissue
B. It causes radiation poisoning
C. It causes the blood count to reach a dangerously low level
D. It cools body tissue
It causes heating of body tissue, just as a microwave heats food, answer A.
G0A02
Which of the following is used to determine RF exposure from a transmitted signal?
A. Its duty cycle
B. Its frequency
C. Its power density
D. All these choices are correct
It is all these factors, answer D.
G0A03 [97.13(c)(1)]
How can you determine that your station complies with FCC RF exposure regulations?
A. By calculation based on FCC OET Bulletin 65
B. By calculation based on computer modeling
C. By measurement of field strength using calibrated equipment
D. All these choices are correct
Each of these are options, answer D.
G0A04
What does "time averaging" mean in reference to RF radiation exposure?
A. The average amount of power developed by the transmitter over a specific 24 hour period
B. The average time it takes RF radiation to have any long-term effect on the body
C. The total time of the exposure
D. The total RF exposure averaged over a certain time
This is ability to average RF exposure over a period, such as 6 minutes, answer D.
G0A05 [97.13(c)(2), 1.1307(b)]
What must you do if an evaluation of your station shows RF energy radiated by your station exceeds permissible limits for possible human absorption?
A. Take action to prevent human exposure to the excessive RF fields
B. File an Environmental Impact Statement (EIS-97) with the FCC
C. Secure written permission from your neighbors to operate above the controlled MPE limits
D. All these choices are correct
You need to take action to prevent exposure at excessive levels, such as raising the antenna, answer A.
You can also reduce power when transmitting in that direction, or move the antenna away from the property boundary.
G0A06 [97.13(c)(2), 1.1307(1)(b)(3)(i)]
What must you do if your station fails to meet the FCC RF exposure exemption criteria?
A. Perform an RF exposure evaluation in accordance with FCC OET Bulletin 65
B. Contact the FCC for permission to transmit
C. Perform an RF exposure evaluation in accordance with World Meteorological Organization guidelines
D. Use an FCC-approved band-pass filter
You need to do the more complicated RF exposure evaluation, in accordance with FCC OET Bulletin 65, answer A.
The WMO is real, but perhaps they are conflating Meteorology, the study of weather and climate change, with Metrology, the science and practice of measurement.
G0A07
What is the effect of modulation duty cycle on RF exposure?
A. A lower duty cycle permits greater power levels to be transmitted
B. A higher duty cycle permits greater power levels to be transmitted
C. Low duty cycle transmitters are exempt from RF exposure evaluation requirements
D. High duty cycle transmitters are exempt from RF exposure requirements
A low duty cycle means that the short-term power can be higher, answer A.
The addition of the word "modulation" means that we can compare something like SSB, where power varies, with AM or FM, where power is constant.
If 500 watts was the limit using AM or FM, you can apply a duty cycle of say 20% by using SSB, and 1500 watts becomes the limiting factor.
G0A08 [97.13(c)(2)]
Which of the following steps must an amateur operator take to ensure compliance with RF safety regulations?
A. Post a copy of FCC Part 97.13 in the station
B. Notify neighbors within a 100-foot radius of the antenna of the existence of the station and power levels
C. Perform a routine RF exposure evaluation and prevent access to any identified high exposure areas
D. All these choices are correct
You must perform the routine RF exposure valuation; you may need to rope off certain areas, or put up a Keep Out sign, answer C.
For stations running 100 watts on HF, or similar power on VHF into a small Yagi, this may well comply as long as antennas are beyond touching distance (2.5 metres) from the fenceline. An array of longer Yagis, combined with an amplifier may exceed the safe level.
G0A09
What type of instrument can be used to accurately measure an RF field?
A. A receiver with digital signal processing (DSP) noise reduction
B. A calibrated field strength meter with a calibrated antenna
C. An SWR meter with a peak-reading function
D. An oscilloscope with a high-stability crystal marker generator
This is the calibrated meter with a calibrated antenna, answer B.
Just link "accurate" and "calibrated" in your mind.
G0A10
What should be done if evaluation shows that a neighbor might experience more than the allowable limit of RF exposure from the main lobe of a directional antenna?
A. Change to a non-polarized antenna with higher gain
B. Use an antenna with a higher front-to-back ratio
C. Take precautions to ensure that the antenna cannot be pointed in their direction when they are present
D. All these choices are correct
You need to make sure you don't point antenna in their direction when they are home, if operating at full power, answer D.
Presumably something like some red tape or marker in the relevant direction.
If you run the calculation for 5 or 10 watts you should demonstrate that you can still use the antenna to access a nearby repeater, in that direction.
G0A11
What precaution should you take if you install an indoor transmitting antenna?
A. Locate the antenna close to your operating position to minimize feed-line radiation
B. Position the antenna along the edge of a wall to reduce parasitic radiation
C. Make sure that MPE limits are not exceeded in occupied areas
D. Make sure the antenna is properly shielded
You need to make sure limits are not exceeded in an occupied area, answer C.
G0A12 [1.1307(1)(b)(3)(i)(A)]
What stations are subject to the FCC rules on RF exposure?
A. All commercial stations; amateur radio stations are exempt
B. Only stations with antennas lower than one wavelength above the ground
C. Only stations transmitting more than 500 watts PEP
D. All stations with a time-averaged transmission of more than one milliwatt
The is just 1 mW (!), answer D.
A "station;" in this case can include a camera capsule which passes through your body, transmitting images of your GI tract over tens of hours. You would not want it "microwaving" you internally. Another example is a system transmitting telemetry to the nurse's desk for weeks on end.
I'm sure you could put one through a male bovine, and not see as much "byproduct" as you would on Fox or Sky.
G0B01
Which wire or wires in a four-conductor 240 VAC circuit should be attached to fuses or circuit breakers?
A. Only the hot wires
B. Only the neutral wire
C. Only the ground wire
D. All wires
Remember that this is the US "split phase" system, used for large loads, and the two hot lines should be fused. The neutral should not be fused, and most definitely NOT the ground or earth. Answer A.
G0B02
According the National Electrical Code, what is the minimum wire size that may be used safely for wiring with a 20-ampere circuit breaker?
A. AWG number 20
B. AWG number 16
C. AWG number 12
D. AWG number 8
This is AWG number 12 wire, answer C.
This is a respectable 3.31 mm².
G0B03
Which size of fuse or circuit breaker would be appropriate to use with a circuit that uses AWG number 14 wiring?
A. 30 amperes
B. 25 amperes
C. 20 amperes
D. 15 amperes
No 14 is only suitable for 15 amps, answer D.
The is 2.08 mm². In both cases these sizes exceed the requirements in Australia for use at this current.
G0B04
Where should the station's lightning protection ground system be located?
A. As close to the station equipment as possible
B. Outside the building
C. Next to the closest power pole
D. Parallel to the water supply line
A system of earth rods should be placed outside the building, along with bonding to things like waterpipes, and to the building's ground, answer B.
You want to divert as much energy to ground before the coax, etc comes inside.
G0B05
Which of the following conditions will cause a Ground Fault Circuit Interrupter (GFCI) to disconnect AC power?
A. Current flowing from one or more of the hot wires to the neutral wire
B. Current flowing from one or more of the hot wires directly to ground
C. Overvoltage on the hot wires
D. All these choices are correct
These are also called RCDs (residual current devices), ELCBRs (Earth Leakage Core Balance Relays), or Safety Switches, and detect when current is flowing to earth, and disconnect the power in a fraction of a second, answer B.
An imbalance in current flowing in the power carrying wires indicates that current is flowing to ground (earth).
G0B06
Which of the following is covered by the National Electrical Code?
A. Acceptable bandwidth limits
B. Acceptable modulation limits
C. Electrical safety of the station
D. RF exposure limits of the human body
This is the electrical safety standard which applies to pretty much any place a ham shack can be, including homes, residential care centres, schools, community centres, emergency operations centres, and to mains voltage wiring in RVs, answer C.
Hams in other countries must comply with the standards in their countries, such as the AS/NZS 3000 series Downunder (although this standard does have an exemption clause regarding secured areas where there are only technically competent people).
G0B07
Which of these choices should be observed when climbing a tower using a safety harness?
A. Always hold on to the tower with one hand
B. Confirm that the belt is rated for the weight of the climber and that it is within its allowable service life
C. Ensure that all heavy tools are securely fastened to the belt harness
D. All these choices are correct
Ensure that the belt is correctly rated, and in date, answer B.
That said, appropriate measures should be taken to avoid tools falling.
G0B08
What should be done before climbing a tower that supports electrically powered devices?
A. Notify the electric company that a person will be working on the tower
B. Make sure all circuits that supply power to the tower are locked out and tagged
C. Unground the base of the tower
D. All these choices are correct
Breakers for electrical equipment on the tower must be locked out, and tagged. This might be microwave gear, and lighting. Answer B.
Disabling daytime strobes may require notification to the FAA, ahead of work.
G0B09
Which of the following is true of an emergency generator installation?
A. The generator should be located in a well-ventilated area
B. The generator must be insulated from ground
C. Fuel should be stored near the generator for rapid refueling in case of an emergency
D. All these choices are correct
Due to carbon monoxide, and other toxic exhaust components, these must be located in a well ventilated area, answer A.
When generators are professionally installed in buildings, properly engineered inlet, exhaust and cooling systems are provided.
Generators, like all small gasoline (petrol) engines, produce significant amounts of toxic (and odourless) carbon monoxide, in addition to carbon dioxide, oxides of nitrogen, partially burnt fuel, and particulates. California has wisely banned new petrol lawn equipment, chainsaws, and golf carts from 2024, and will ban new petrol generators from 2028, with use to end in 2035.
G0B10
Which of the following is a danger from lead-tin solder?
A. Lead can contaminate food if hands are not washed carefully after handling the solder
B. High voltages can cause lead-tin solder to disintegrate suddenly
C. Tin in the solder can "cold flow" causing shorts in the circuit
D. RF energy can convert the lead into a poisonous gas
Lead is toxic, and if you don't carefully wash your hands (including thumbs) after soldering, you can contaminate food, answer A.
The same probably applies to smoking, although with hundreds of other toxic substances involved, the lead is possibly down the list of hazards. One is radioactive Polonium-210, taken up by the plant, which decays in your body, generating alpha particles, damaging DNA, and leading to cancer.
Cold-flow is really only a problem with near pure tin; and joint failure due to extreme currents (lighting, serious mains faults) relates to any soldered joint. Mechanical jointing, such as crimping or clamping, is much better for high current joints, such as station earths. CAD welding, using copper thermite, is popular for earths on the US.
G0B11
Which of the following is good practice for lightning protection grounds?
A. They must be bonded to all buried water and gas lines
B. Bends in ground wires must be made as close as possible to a right angle
C. Lightning grounds must be connected to all ungrounded wiring
D. They must be bonded together with all other grounds
The lightning ground must be bonded to other grounds, such as power earth, answer D.
Cabling should be as straight as possible, or use gentle curves.
G0B12
What is the purpose of a power supply interlock?
A. To prevent unauthorized changes to the circuit that would void the manufacturer's warranty
B. To shut down the unit if it becomes too hot
C. To ensure that dangerous voltages are removed if the cabinet is opened
D. To shut off the power supply if too much voltage is produced
These either cut-off power, or short dangerous voltages to ground (blowing the fuse) to ensure these are not present when the cabinet is open, answer C.
The correct procedure is to remove power, and wait a period for the capacitors to discharge, then open the cabinet, and to check using a meter with a suitable High Voltage probe.
G0B13
Where should lightning arrestors be located?
A. Where the feed lines enter the building
B. On the antenna, opposite the feed point
C. In series with each ground lead
D. At the closest power pole ground electrode
In most cases these should go where the feedline enters the building, answer A.
These are made by companies such as PolyPhaser, Alpha Delta, TE Connect, Amphenol, Times Microwave Systems, and others. They are rated for specific range of frequencies, power levels, and connector types. If multiplexing several signals together on a repeater site (say ham FM, ham DMR, non-ham frequencies for an emergency support group, and the like, take into account that these together may cause the protection to start to trip. These need a solid connection to the station earth. Occasionally they may be placed on an equipment rack at a repeater site, if good engineering practice dictates this.
CONGRATULATIONS! You have now reviewed all questions.
I would suggest doing some drills on hamtestonline.com, which are available without charge.
It is also time to look at Exams.
You can also continue to the Extra paper. The first, a Regulations page, is here: Regulations 1. Reading all regulations parts at your leisure is probably a good idea anyway)
You can find links to lots more on the Learning Material page.
This has taken a fair bit of work to write, so if you have found this useful, there is a "tip jar" below.
You may also want to get a Ham related shirt, sticker, mug, etc, designed by your author: Australian style route marker designs with HAM / AMATEUR RADIO - 73 which includes "Keep Calm and Send Morse" products; or Be Great - Don't Overmodulate
Written by Julian Sortland, VK2YJS & AG6LE, February 2026.
Tip Jar: a Jefferson (US$2), A$3 or other amount / currency. Thanks!
You can also buy me a non-coffee beverage: ko-fi.com/ag6le