The real reason why North America uses 120v instead of 240v. - Page 1
Forum section: electronics / general

author: BrianHG
author_rank: Super Contributor
timestamp: November 24, 2022, 06:30:13 pm
content: If you wanted to know, here is why...

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2022, 06:37:23 pm
content: Not to be picky or anything, but as per the video title and meter displayed in the thumbnail, North America uses 120 V, not 110 V...

author: BrianHG
author_rank: Super Contributor
timestamp: November 24, 2022, 06:43:32 pm
content: Quote from: IanB on November 24, 2022, 06:37:23 pmI changed it, happy?BTW, it used to be 110v and since it is a historical video...

author: MikeK
author_rank: Super Contributor
timestamp: November 24, 2022, 06:55:04 pm
content: Do countries that use 240V have two out-of-phase 120V lines (like the US actually has), or do they just have a single 240V line?

author: Gyro
author_rank: Super Contributor
timestamp: November 24, 2022, 07:10:59 pm
content: A single 230-240V Line and a Neutral.Edit: That's unless you want to get into 3-phase supplies (typically not domestic, at least, not in the UK).

author: jpanhalt
author_rank: Super Contributor
timestamp: November 24, 2022, 07:13:17 pm
content: Two minutes of information at most compressed to 14 minutes of palaver. Her enunciation is terrible and even as an American, she is harder to understand than our exalted leader Dave. America is at 120V because that's where we started and its safer than 220-240 V. More copper is needed, but lives are more important.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 24, 2022, 07:15:00 pm
content: Quote from: MikeK on November 24, 2022, 06:55:04 pmEurope to a large part has 3 phase 230 V. So 3x230 V to ground and ~400 from phase to phase. Some smaller private installations only get 1 phase.

author: themadhippy
author_rank: Super Contributor
timestamp: November 24, 2022, 07:20:36 pm
content: Quotein the uk generally you get 240V (supposedly its 230,but theirsa fudge factora bit of tolerance so can legally be anywhere from 216v to 253v,between live and neutral, or 3 phases 120 degrees apart that gets you 415V between phases.

author: TimFox
author_rank: Super Contributor
timestamp: November 24, 2022, 07:47:58 pm
content: What I find interesting is that the normal domestic voltage in Japan is 100 V, but the country is split roughly in two between 50 Hz and 60 Hz distribution.

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 07:55:36 pm
content: Quote from: jpanhalt on November 24, 2022, 07:13:17 pmAnd yet more people still die of electrical shock and electrical fires in the US than in 230V nations. In 2017, 13 shock deaths were recorded in England. In 2020,126were recorded inwork-place incidents alonein the USA.Tell me again how your standards and accompanying attitudes are safer.

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2022, 07:57:18 pm
content: Quote from: MikeK on November 24, 2022, 06:55:04 pmIt is single phase 240 V, but wiring and appliances are supposed to assume that both line and neutral conductors are live, and each has to be equally insulated from any exposed parts that could be touched.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 24, 2022, 07:58:45 pm
content: Quote from: IanB on November 24, 2022, 07:57:18 pmYep.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 24, 2022, 08:08:50 pm
content: Quote from: Monkeh on November 24, 2022, 07:55:36 pmI would like to read your source. What is it? How were populations and usage matched? For example, in Lesotho, 240 may be the standard, but the vast majority of the population doesn't use it as frequently as in America.

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 08:12:04 pm
content: Quote from: jpanhalt on November 24, 2022, 08:08:50 pmWhat does Lesotho have to do with the price of powdered milk on Mars? Are you somehow imagining England as an unelectrified backwater?My sources are publications from the Office for National Statistics and the NFPA. I'm sure you can find them.

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2022, 08:16:27 pm
content: I'm sure I saw a video recently saying that electrical accidents have paradoxically been increasing in the years since the government introduced regulations with the intention of making things safer. But now I can't find the video with any search keywords. Either it is being hidden from the search results, or it got removed for being too alarming for people to see.I think the premise was that anyone can now take a short training course and become "qualified" as an electrical installer, leading to all sorts of poor quality work. Whereas electricians have to go through years of training and apprenticeship to become properly qualified.

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 24, 2022, 08:19:24 pm
content: Because of inches, feet, pounds and all that standard aberration.But they know very well what 9mm is

author: jpanhalt
author_rank: Super Contributor
timestamp: November 24, 2022, 08:24:55 pm
content: @Monkeh,If you have so many sources, it should be easy for you to cite at least two comparisons. So?

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 09:00:01 pm
content: Quote from: jpanhalt on November 24, 2022, 08:24:55 pmAnd your source that 120V actually works out safer in practice? Thought not.https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/adhocs/14400deathswhereicd10codesw86orw87wererecordedastheunderlyingcauseengland2019to2020registrationshttps://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/Electrical/osFatalElectricalInjuries.pdf

author: jpanhalt
author_rank: Super Contributor
timestamp: November 24, 2022, 09:09:02 pm
content: Neither of those links compare death from 120V to 240V.Please provide your data/links that show electrical shock from 240V in not more lethal than shock from 120V.

author: TimFox
author_rank: Super Contributor
timestamp: November 24, 2022, 09:14:23 pm
content: Quote from: DavidAlfa on November 24, 2022, 08:19:24 pmThe Volt is a metric unit.When Britain adopted 220 or 240 V, they were not yet metric.When Japan adopted 100 V, they were already metric.I see no correlation.

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 09:21:46 pm
content: Quote from: jpanhalt on November 24, 2022, 09:09:02 pmI didn't say they did, because the data isn't broken down that way.

author: bdunham7
author_rank: Super Contributor
timestamp: November 24, 2022, 09:22:06 pm
content: Quote from: Monkeh on November 24, 2022, 07:55:36 pmThat doesn't really add up as an argument. Workplace safety regulations and the relative compliance with might vary quite a bit, for example. You don't know what voltage the workers were shocked at, either--I'm confident a good proportion were not electrocuted by 120V. There are HVDC solar systems, 480VAC/3-phase (and higher) systems, primary high voltage (3800-14,400V), microwave oven transformers (2 deaths locally that I know about and I'm referring to people repairing the ovens, not the fractal wood burning idiots) and so on. I doubt you are going to be able to really tease out the safety advantage (if any) of 120V. Perhaps we need to shock some sheep or something.When I read reports of these incidents, my reaction generally is one of two things: 1) Wow, what a dumbass! (not necessarily the victim) or 2) Wow, that's a pretty unlikely freakish accident! 90% are probably #1. Older houses, especially attics and crawlspaces, along with barns, seem to be the among the most dangerous places.

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 09:28:58 pm
content: Quote from: bdunham7 on November 24, 2022, 09:22:06 pmBut it's the available data to work with. I chose not to go with the more approximate total figure (upwards of 300) due to lack of motivation to find the specific source. Where's the data to suggest 120V systems and, as I originally stated, the accompanying attitudes regarding safety, are in fact safer?Teasing out good numbers for fires will be even harder - US statistics are as ever hard to locate, and there's no ICD10 code regarding origin of fires (that I know of), they'd all come under X00.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 24, 2022, 09:48:49 pm
content: 110V was the standard in most european countries before switching to 220V (which became 230V to 240V depending on the country.)Sure switching to a higher voltage allowed lower currents, so lower losses. Beyond that, I think there were studies showing that 110V was actually more dangerous.But people in the US were usually told the opposite.While, for the same impedance, the current through your body would be twice as high with 220V as opposed to 110V - which was the main rationale invoked - and sure, the higher the current, the higher the risk. Right?Now in those ranges, typically a few tens of mA unless your skin is very wet, it's mostly energy that matters, so the duration is key. I have consistently heard that on average, for people with no specific health condition, 220V was more likely to trigger a withdrawal reflex (thus a very short exposure), while 110V was more likely to trigger muscle tetany (thus longer exposure.) I have no paper right now to back this up though.The real reason, in both cases though, is just likely to be purely economical.All I can draw from my own experience is that I sure did get shocked quite a few times with 220V in my life and always got a strong withdrawal reflex with no more consequence than an elevated heart rate for a couple minutes.

author: rstofer
author_rank: Super Contributor
timestamp: November 24, 2022, 10:04:17 pm
content: Quote from: DavidAlfa on November 24, 2022, 08:19:24 pmAnd 5.56mm and 7.62 mm and 106mm. Some of the long range guys are familiar with 6.5mm as in 6.5x284 Norma.https://weaponsystems.net/system/1341-106mm+M40The M40 was usually Jeep mounted on an M151A1CAnd people think we don't use metric...

author: bdunham7
author_rank: Super Contributor
timestamp: November 24, 2022, 10:06:08 pm
content: Quote from: Monkeh on November 24, 2022, 09:28:58 pmI see no reason to think that certain attitudes 'accompany' 120V systems and don't know why you'd lump them somehow as if Americans are less worried about shocks because the voltage is lower. Would you be more likely to ignore the railway crossing lights if the train was a passenger train vs a freight train?What I said was that I don't think you are going to be able to tease out meaningful data that really shows you that one voltage is safer than the others using shock fatality stats from two different areas with other variables in play. IOW, your statistics are meaningless for this purpose, IMO. It could be that Americans, due to stupidity and neglect, get shocked 300X more often by 120V than Brits do by 240V, but only have 4X the fatality rate. That would make 120V 75X safer. Or maybe not.

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 10:15:44 pm
content: Quote from: bdunham7 on November 24, 2022, 10:06:08 pmhttps://www.eevblog.com/forum/projects/can-i-convert-a-atx-psu-to-run-directly-off-of-12v/msg4498369/#msg4498369That's far from my only personal experience of how people treat 120V systems as 'safe' because it is 'safer'.QuoteI have just recently seen someone step out in front of a learner driver because they believe the instructor will stop them. So yes, people will treat dangerous situations differently based upon their misguided preconceptions.QuoteAnd I agree that it isn't easy to draw conclusions from the data - but I find it unlikely that the most commonly accessible voltage is in fact safer when fatalities are 20-30x higher for only 6x the population.

author: themadhippy
author_rank: Super Contributor
timestamp: November 24, 2022, 10:30:21 pm
content: maybe its down the shite quality of electrical work,look at the state of the american fuse boards posted in the "show your fuse board " thread,or compare the popular uk electrical youtube channels with american equivalent.Take a typical american electrical accessory,its either stab and pray,or wrap the wire around an exposed screw, or there the love of wire nuts.

author: mcovington
author_rank: Regular Contributor
timestamp: November 24, 2022, 11:19:35 pm
content: There are at least 4 safety differences.(1) 120 V is supposedly less lethal than 240 V, but I don't know if the difference is significant in practice. I wouldn't want to be shocked by either one.(2) 240 V requires half as many amps to deliver the same amount of power, and thus, only 1/4 as much heat dissipated in a poor connection.(3) To further mitigate the effect of poor connections in house wiring, Britain, as I understand it, commonly uses ring arrangements where there are two paths from source to load; North American never does. (Is it even permissible in North America? Does Australia use it?)(4) Fuses in plugs or outlets and switches on outlets are, as I understand it, usual in the UK (also Aus?) but rare in North America.As well as someone mentioned that in 240 V countries, both sides of the power line are expected to be well insulated from anything the user can contact. (That is a reasonable expectation and normal practice in North America as well; I wouldn't build anything any other way.)

author: Monkeh
author_rank: Super Contributor
timestamp: November 24, 2022, 11:24:14 pm
content: Quote from: mcovington on November 24, 2022, 11:19:35 pmDouble edged sword. The purpose is actually to reduce the amount of copper needed to provide flexible placement of loads - specifically, electric heaters. It's a bit out of date these days. While it will reduce the risk of fire from a single loose connection, it also hides the symptoms of said loose connection and can lead to excessive current in one leg for prolonged periods.Basically unused outside of the UK and a few territories.

author: nightfire
author_rank: Frequent Contributor
timestamp: November 24, 2022, 11:39:55 pm
content: To put some stuff as further things in the fire:The human adult body (depending on the path the current flows) is roughly 1000R-2000R. So with 120V there is half the amount of current flowing through your body, and maybe (as it needs some initial voltage to begin going through your skin) in some cases of thick skin a complete accident would have been avoided.so 120V/2000 Ohms=60mA ->way more than the 10mA that are regarded as the area where it gets realllly sticky.When it comes to regulations, it also is important who controls these and who trains the people that do the installation stuff. Here in germany as an electrician, you have to do a longer apprenticeship than most other trades, its 3.5 years. After the exam you still need some masters degree to be able to really run a company alone due to some regulations. Also regarding workspace safety, both by law and by your workplace insurers it is mandated that you have to do some danger assessment of your equipment and regular (read: yearly) testing of your appliances. If you have low stress on them, like PC in an office, you can prolong that to every two years.So the awareness for safety is a bit higher, and you have ready access to qualfied people.When you live in an area that is sparsely populated, lots of people are DIY, and thats where potential issues occur. Or people cheap out on quality parts etc.I also read a statistic from a (i think french) power company where lots of maintenance things were done with trained people under live voltage, and the accidents decreased. Reason: You are aware of the danger and plan accordingly, because one big cause of accidents is routine with experienced people.Also lots of injuries from electric accidents as the root cause do not originate from the voltage itself, but from surprise and a secondary accident like falling from a ladder. Depending on how this is counted, it also might affect the numbers quite a bit, especially when lots of people in the US due to lack of health insurance avoid going directly to the hospital or doctor.

author: bdunham7
author_rank: Super Contributor
timestamp: November 24, 2022, 11:54:19 pm
content: Quote from: Monkeh on November 24, 2022, 10:15:44 pmHmmm. Perhaps you haven't met enough of my fellow Americans. Or seen how some clowns wired my house.

author: thm_w
author_rank: Super Contributor
timestamp: November 24, 2022, 11:56:51 pm
content: Quote from: Monkeh on November 24, 2022, 09:00:01 pmUK is actually lower than Canada in terms of electrocution deaths as well (~50%).Although both are very low overall, 13 for UK per year is nothing compared to other causes (obesity 31k+).Maybe the shrouded plugs and safety shutters help a bit.

author: coppice
author_rank: Super Contributor
timestamp: November 25, 2022, 12:01:16 am
content: Quote from: MikeK on November 24, 2022, 06:55:04 pmMost countries that supply 220V to 240V power use a single phase. However, I know one country which supplies only 220V power (no 110V or 120V) as two out of phase lines - the Philippines. You have to be a bit careful working on stuff there. Its easy to forget that neither wire is close to ground.

author: Monkeh
author_rank: Super Contributor
timestamp: November 25, 2022, 12:02:42 am
content: Quote from: bdunham7 on November 24, 2022, 11:54:19 pmI've seen what passes for professionally installed wiring in brand new homes, which is bad enough. Refers straight back to my point on accompanying attitudes.Quote from: thm_w on November 24, 2022, 11:56:51 pmIs that adjusted for population or absolute? Because the population of England is 50% greater than Canada.

author: thm_w
author_rank: Super Contributor
timestamp: November 25, 2022, 12:10:13 am
content: Quote from: Monkeh on November 25, 2022, 12:02:42 amYes, that was based off the Ontario number of 5 deaths, which has a population about 4x less than England.

author: IanB
author_rank: Super Contributor
timestamp: November 25, 2022, 12:16:37 am
content: Quote from: Monkeh on November 25, 2022, 12:02:42 amNew homes are going to be the worst, especially when they are part of a large development. When they have dozens or hundreds of homes to build, they are going to do each one as quickly and cheaply as possible. That's why there is "back stab" wiring in the USA. The apprentice who gets to wire up all the light switches and sockets doesn't even need a screwdriver to do the wiring. Just strip the insulation, stab the wire into the terminal, and done. (Mind you, I see Wago learned from that, as there are now push fit Wago connectors.)Another thing that really annoys me is when said apprentice uses a power driver to do up the screws on the receptacle and strips the threads by over torqueing. Nearly all the wall boxes in my house have had their threads stripped like that.

author: Monkeh
author_rank: Super Contributor
timestamp: November 25, 2022, 12:29:33 am
content: Quote from: IanB on November 25, 2022, 12:16:37 amThe push-fit Wagos and similar are effectively identical to lever operated types, just without the lever. They're of far higher standard than the crap in receptacles, thankfully - there are meaningful standards applied to them.

author: IanB
author_rank: Super Contributor
timestamp: November 25, 2022, 12:39:24 am
content: Quote from: Monkeh on November 25, 2022, 12:29:33 amThere is an amusing tier system of receptacles (plug sockets) here in the USA:"Consumer grade" -- Quite likely to melt and catch fire"Commercial grade" -- Probably will not catch fire"Hospital grade" -- Very solidly built, likely to lastThere is a corresponding price scale, which means few people are going to spend the money on hospital grade items.Guess what gets installed in new homes?(Also, guess why the latest electrical code insists on arc fault circuit interrupters?)

author: Someone
author_rank: Super Contributor
timestamp: November 25, 2022, 01:58:13 am
content: Ok, here is a topic I know quite a bit about. Household mains in Australia, although 240V (the more dangerous kind) is a vanishingly small proportion of electrical deaths:https://www.erac.gov.au>95% of deaths are from distribution infrastructure, only a tiny percent are from interaction with 240V.We do have international standards for electrical hazards like the Test and Measurement standard 61010. That has within it various graphs for "acceptable" exposures:maximum single fault duration (dry conditions): 110V AC 200ms, 240V AC 40ms, 5x shorter exposurenormal (non fault) accessible capacitance: 110V DC 4uF 24mJ, 240V DC 1.5uF 43mJ, higher energy permissible for higher voltage!It is not always a clear cut more = worse, or a steady relationship. How about:"Effects of current on human beings and livestock" IEC 60479Median body impedance, hand to hand (dry): 100V 1725ohm 60mA, 225V 1225ohm 200mAIts those (median) currents where the difference lies. 110V is unlikely to produce heart or breathing arrest even with a sustained exposure, while 240V is almost certainly going to interrupt essential body functions unless the exposure is limited in duration to only a few to a dozen cycles of the line frequency.Hence residual current devices cutting off power in 200ms (matching the 240V line for the 60479 standard) and them being mandated in all consumer settings.

author: Someone
author_rank: Super Contributor
timestamp: November 25, 2022, 02:01:30 am
content: Quote from: IanB on November 25, 2022, 12:39:24 amThis is the downside of 110V delivery, increased risk of fire from the electrical installation. Such fires are barely evident in 240V systems historically, but widespread multi kW vehicle charging will likely change that!

author: IanB
author_rank: Super Contributor
timestamp: November 25, 2022, 02:55:21 am
content: Quote from: Someone on November 25, 2022, 02:01:30 amIt's more a question of quality control. For instance, I have a 1500 W electric kettle, which has a figure 8 zip cord and moulded on plug. When I use the kettle, the plug gets notably warm, even hot, where the cable joins it. I'm not sure what kind of connection exists between the conductors and the plug pins hidden inside the plastic moulding, but I don't think it is very good. Soldered? Crimped? I have my doubts.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 25, 2022, 10:13:11 am
content: North America does not use "120V instead of 240V". North America uses BOTH 120V and 240V. It's a pretty clever system although one could claim ours is simpler, with one voltage and one plug. OTOH, our plug is limited to ~2.5kW continuous. Households in the US of A have higher-power sockets available, if not in every room, but at least a few in the house!

author: jonpaul
author_rank: Super Contributor
timestamp: November 25, 2022, 10:23:19 am
content: My recollection...Thomas Edison setup first electrical distribution in 1880s Pearl St DC generators serving lower Manhattan.The gutta percha insulation led to 100V tension.Later, the industry advanced to AC distribution, the service voltage was increased to 120V to compensate for copper losses.Nowadays Con Edison has a 12 kV mesh underground network, with 12 k to 240V/ 120 single phase or 208 V delta three phase.Just the ramblings of an old retired EEJon

author: snarkysparky
author_rank: Frequent Contributor
timestamp: November 25, 2022, 11:18:22 am
content: My guess is that the vast majority of electrical shock fatalities are in industrial settings. 480 VAC and much higher.So unless there is data that breaks our household electrical shock fatalities the data is meaningless to the discussion.Also i would guess there is some nonlinear effect in the current induced by the voltage. 48 VAC is unlikely to provide more than a tingle unless wet. 120 VAC could be just an annoyance. Many electricians in the USA test for hot on 120 VAC by lightly touching the wires. Step up to 480 VAC ( which is 277 to ground) and things become much more serious.In Britain what is the voltage to earth in their systems?

author: pcprogrammer
author_rank: Super Contributor
timestamp: November 25, 2022, 11:40:41 am
content: Quote from: SiliconWizard on November 24, 2022, 09:48:49 pmI can relate to thatHad my fair share of shocks and never had a contracting muscle experience. Not even in a controlled environment where I was pushed forward as volunteer test subject to show that this is the risk of electricity. The instructor strapped a conductive belt around my arm and handed me a pair of pliers. Both wired to a variac. He started turning up the voltage, and at some point the tingle became to strong so I let go of the pliers. Not the result he hoped to getAnother time was, when I was helping out a friend with some remodeling. Needed to remove some light fixtures. Disconnected the assumed live wire and started removing the lights. At some point I felt some tingling sensation, and thought, this is strange. Went to the box with the mains connection and it turned out some joker had swapped the live and neutral wires

author: Tangent_Tracker
author_rank: Regular Contributor
timestamp: November 25, 2022, 11:55:28 am
content: Quote from: IanB on November 24, 2022, 07:57:18 pmWe certainly have the safest plug and socket system in the world I think. That is our saving grace.

author: tom66
author_rank: Super Contributor
timestamp: November 25, 2022, 12:12:17 pm
content: Quote from: Someone on November 25, 2022, 02:01:30 amApologies if I'm misreading you, but since most EVs are charged from 240V will there be much of a difference here between the US and elsewhere?

author: Someone
author_rank: Super Contributor
timestamp: November 25, 2022, 12:46:55 pm
content: Quote from: tom66 on November 25, 2022, 12:12:17 pmFew people experience joule heating in day to day 240V appliance wiring (or household wiring) because there is ample power at "reasonable" current. But high power EV charging includes thermal management for the cabling! Hot cables are something new for consumers and the "clever idiot" will find some way to defeat the safety systems and/or plug into normal circuits (normal here and in the UK for a set of power points to have a breaker rated higher than any single point could safely supply).Domestic fires from electrical distribution faults are still unusual in Australia, but the thermal sources are changing:https://rac.com.au/home-life/info/house-fire-causesLithium battery charging is becoming a noticeable cause of house fires (we'd guess from junk cells and inappropriate charging).Where as US data has arcing of fixed wiring as the major cause:https://www.nfpa.org/News-and-Research/Data-research-and-tools/Electrical/ElectricalIs that from relaxed regulations/compliance/enforcement or the lower voltage? Probably both.PS. get smoke alarms, they really do save lives for little cost.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 25, 2022, 01:25:18 pm
content: Why not have 120V be 2x 60V to ground? Wouldn't that be the safest way to have 120V?

author: themadhippy
author_rank: Super Contributor
timestamp: November 25, 2022, 01:31:47 pm
content: QuoteWe do in the uk.ok its 55-0-55v ,it mainly used on construction sites.

author: Monkeh
author_rank: Super Contributor
timestamp: November 25, 2022, 02:55:47 pm
content: Quote from: snarkysparky on November 25, 2022, 11:18:22 amOf the 13 I mentioned in England, 7 were in homes - no 480VAC in homes. Actually, no 480VAC at all, not that shocks between phases are common.. In 2020, there were 14 - 4 of them in homes.Of the 126 workplace fatalities in the US, 13 examples were given. Three were almost certainly only 120VAC, a fourth highly unlikely to be greater than that. The others vary, several are likely to have been 120VAC and a few more, 277VAC (one phase of 480VAC, because again, contact between phases is unlikely). Contact with overhead lines is remarked to be the most common cause, however, but the voltage of those is unspecified. 120VAC lines aremuchlower down than higher voltage supplies, of course..As a curious aside which I'm tempted to contact the ONS about, in 2018 a 7 year old boy was electrocuted at a pub in Essex by faulty outdoor lighting. This age group does not appear in the released data..

author: AVGresponding
author_rank: Super Contributor
timestamp: November 25, 2022, 03:38:23 pm
content: Quote from: Monkeh on November 25, 2022, 02:55:47 pmLarger homes often have 3-ph supplies in the UK.

author: Monkeh
author_rank: Super Contributor
timestamp: November 25, 2022, 03:41:56 pm
content: Quote from: AVGresponding on November 25, 2022, 03:38:23 pmI wouldn't say often, and many DNOs actively refuse to supply such. And still not 480VAC.Mind you, there's the far rarer option of a split-phase supply.. never say never, I guess.

author: mcovington
author_rank: Regular Contributor
timestamp: November 25, 2022, 03:49:12 pm
content: Quote from: Tangent_Tracker on November 25, 2022, 11:55:28 amAre you referring to the UK, Australia, or somewhere else? The tiny plugs in the US certainly don't give me a lot of confidence.

author: mcovington
author_rank: Regular Contributor
timestamp: November 25, 2022, 03:50:23 pm
content: Quote from: NiHaoMike on November 25, 2022, 01:25:18 pmI like that idea -- with GFCIs (residual current devices) on both sides. Hmmm... Currently existing American appliances would all work, I think.

author: mcovington
author_rank: Regular Contributor
timestamp: November 25, 2022, 03:51:06 pm
content: Quote from: themadhippy on November 25, 2022, 01:31:47 pmInteresting. With American-type 120V tools?

author: AVGresponding
author_rank: Super Contributor
timestamp: November 25, 2022, 03:57:17 pm
content: Quote from: Monkeh on November 25, 2022, 03:41:56 pmI would, and I've worked in a few. When you get to the size of 10+ bedrooms and multiple wings and/or sub-buildings, it's common, and necessary. And 3-ph in the UK is most commonly 400VAC (nominally, actually more like 415, blame weird EU harmonisation attempts, just like the "230" in the UK is more likely to be between 240 and 250), not 480. Some specialised use cases exist of course, ie railway signalling at 650VAC 1-ph etc.

author: TimFox
author_rank: Super Contributor
timestamp: November 25, 2022, 03:57:58 pm
content: Quote from: mcovington on November 25, 2022, 03:51:06 pmI encountered the 110 VCT transformers during an installation in UK: it seems to be mandated when a long extension cord is required from the wall to a power tool.The connectors used are quite different from normal UK or US plugs.The local workers did not use these extra transformers very often, using cordless power tools (battery operated) when possible to meet the safety regulations.

author: themadhippy
author_rank: Super Contributor
timestamp: November 25, 2022, 04:28:52 pm
content: Quotenope,its just to reduce the risk of a fatal shock on damp building sitesQuotecompared to domestic stuff yes,but fairly common else were and come in a wide variety of voltage and current ratings

author: mcovington
author_rank: Regular Contributor
timestamp: November 25, 2022, 05:14:12 pm
content: Quote from: themadhippy on November 25, 2022, 04:28:52 pmWhere can I see a picture of one?

author: IanB
author_rank: Super Contributor
timestamp: November 25, 2022, 05:19:23 pm
content: Quote from: mcovington on November 25, 2022, 05:14:12 pmhttps://en.wikipedia.org/wiki/IEC_60309

author: Zero999
author_rank: Super Contributor
timestamp: November 25, 2022, 06:44:05 pm
content: Quote from: Kleinstein on November 24, 2022, 07:15:00 pmThen that would be 400V three phase. 230V three phase would be 133V to neutral, which is uncommon.

author: JPortici
author_rank: Super Contributor
timestamp: November 25, 2022, 09:17:29 pm
content: Quote from: Zero999 on November 25, 2022, 06:44:05 pmIn italy there should still be some areas in Turin and Rome with three phase 230V, no neutral (residential utilities are connected between two phases)however the last i heard of it is that they started converting to the current 400V 3phase + neutral

author: Nusa
author_rank: Super Contributor
timestamp: November 25, 2022, 10:28:14 pm
content: Quote from: Tangent_Tracker on November 25, 2022, 11:55:28 am"we" and "our" have no meaning when you don't identify where you are. You don't have the country code set on your identity, so we don't even have an assumption to go with.

author: PlainName
author_rank: Super Contributor
timestamp: November 26, 2022, 01:22:08 am
content: Quote from: Monkeh on November 24, 2022, 10:15:44 pmThe UK stats are all W86 ("Exposure to other specified electric current") and W87 (""Exposure to unspecified electric current"), and roughly half are "Trade and service area" and "Industrial and construction area". So they are likely 240V but with a high probability of 120V (constructions, etc). There is W85 ("Exposure to electric transmission lines") which doesn't appear in the stats, so we are talking all low voltage.By contrast, the US stats include people snipping primary distribution lines (5+kV). Their stats include much higher voltages than the UK ones. If there is any question, it is why the UK seems not to have had any high voltage fatalities (unless the selected stats excludes them, in which case it's apple vs oranges).

author: Monkeh
author_rank: Super Contributor
timestamp: November 26, 2022, 02:08:40 am
content: Quote from: PlainName on November 26, 2022, 01:22:08 amThe W85 numbers are.. minimal. 2 in 2013, 4 in 2014, 3 in 2016, 6 in 2017 (rough year.), 2 in 2018, 2 in 2019, 2 in 2021.

author: AVGresponding
author_rank: Super Contributor
timestamp: November 26, 2022, 06:48:35 am
content: Quote from: TimFox on November 25, 2022, 03:57:58 pmGenerally speaking, 240V tools are not permitted on construction sites, regardless of cable length. Using battery tools is usually a matter of convenience, but for heavier tasks, the leaded 110V stuff gets used. Better to put wear on the gearbox of the hired SDS hammer drill than my own battery one!

author: PlainName
author_rank: Super Contributor
timestamp: November 26, 2022, 11:10:36 am
content: QuoteOne interpretation might be that the higher the voltage the safer it is! But I think it's more likely that anyone going near that stuff is trained to a high standard and using equipment appropriate to the environment.

author: mcovington
author_rank: Regular Contributor
timestamp: November 26, 2022, 03:57:12 pm
content: A couple of thoughts:- Maybe people working on 240V are more careful.- The US has more sparsely populated places, farms, and (presumably) DIYers.

author: jmelson
author_rank: Super Contributor
timestamp: November 26, 2022, 06:31:22 pm
content: Quote from: bdunham7 on November 24, 2022, 09:22:06 pmYup, poking around inbasement ceilings and inside walls of houses with knob and tube wiring, you will find bare conductors all over the place where you least expect it!Jon

author: Gyro
author_rank: Super Contributor
timestamp: November 26, 2022, 11:21:49 pm
content: Quote from: AVGresponding on November 26, 2022, 06:48:35 amThat really ought to be discriminated as 55-0-55V rather than 110V. In the case of accidental contact you'd only get hit with 55V, it would take holding one wire in each hand to get a 110V shock. It's almost SELV.

author: AVGresponding
author_rank: Super Contributor
timestamp: November 27, 2022, 08:34:23 am
content: Quote from: Gyro on November 26, 2022, 11:21:49 pmIt's easier to just refer to it as 110V, and in the cases of CPC failure, class 2 devices (many drills etc are this now) and festoon lighting (where there is no CPC) for example, that's exactly what it is.The inclusion of a CPC would make it PELV, not SELV, and it would have to be under 50V between any two conductors to meet the criteria for either.

author: mfro
author_rank: Regular Contributor
timestamp: November 27, 2022, 10:14:12 am
content: Just to fire up discussion:German statisticslist 32 deaths caused by electricity in 2019, 7 of them in industry/commerce (that is: professional) environments.US population is (roughly) four times that of Germany, UK about 20% less.

author: tom66
author_rank: Super Contributor
timestamp: November 27, 2022, 10:28:57 am
content: Quote from: JPortici on November 25, 2022, 09:17:29 pmI know Belgium is similar, in rural areas.Apparently some electric vehicles cannot charge off such 230V 3ph, they require a neutral (they will charge on the slow charger, but not on a wall box.)

author: tooki
author_rank: Super Contributor
timestamp: November 30, 2022, 04:37:22 pm
content: For what it’s worth, I think the Swiss receptacle system (SN 441011) is extremely elegant: it consists of four receptacle types: 10A and 16A, in single-phase and three-phase. 10A plugs fit into 16A sockets (not so special), but the thing that is unique (as far as I’m aware) is that single-phase plugs fit into three-phase sockets.This is extremely practical, for example in laundry rooms, which often have three-phase sockets for the washer and dryer, but which then accept a modern single-phase heat pump dryer without any adapters.Standard 2-pin Europlugs (CEE-7/16, 2.5A) fit into them, too (the standard requires sockets to accommodate them) but not standard European grounded CEE 7/7 (Schuko/F) or the 16A 2-pin (CEE-7/17) European plug.Old versions of the standard had some exposed-metal hazards, but sleeved pins have been required for years, and recessed sockets are now required for all new installations. (In the past they were required only in wet spaces.)It’s curious that all of the newest outlet standards (like the new ones in Brazil and South Africa) are based on the IEC 60906-1 socket, which itself is a tweaked version of the Swiss socket. (All mutually incompatible, of course…)

author: Zero999
author_rank: Super Contributor
timestamp: November 30, 2022, 05:14:16 pm
content: Quote from: tom66 on November 27, 2022, 10:28:57 amThat sounds like bad design to me.If it was designed properly, it would simply rectify the mains to DC, then power everything from that. It shouldn't be difficult to make a charger which would work from 210VAC to 270VAC single phase, or 210V to 440VAC three phase.

author: james_s
author_rank: Super Contributor
timestamp: November 30, 2022, 06:20:22 pm
content: The main advantage I see of 120V is that lower voltage incandescent lamps are substantially more efficient. That is pretty much moot now but for most of the first century of electrification lighting which was primarily incandescent was the largest consumer of electricity. It may be arguably safer, but even 120V can and does kill people. Safety focus should be on preventing shocks more so than surviving them.

author: IanB
author_rank: Super Contributor
timestamp: November 30, 2022, 06:47:22 pm
content: Quote from: Zero999 on November 30, 2022, 05:14:16 pmThere are some special design considerations relating to car chargers concerning the neutral and grounding arrangements, which may be why this limitation exists. I know the neutral is not earth/ground, but I suspect the problem is regulatory rather than technical.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 30, 2022, 07:46:57 pm
content: Quote from: NiHaoMike on November 25, 2022, 01:25:18 pmI found out by coincidence that there is a specific market for construction site power tools, in UK, where it is arranged exactly like this. The argument for it is safety, indeed: they install a step-down transformer to go from 240V to 120V, with a center tap on the output, which is then earthed. Someone who gets shocked between L & earth or N & earth only sees 60VAC, which, while slightly over modern safety limits, is not that dangerous.I found it out in a project where we wanted to equip a robot supplied by 6s li-ion pack with a powerful construction site vacuum cleaner. So I designed a 22V to 74V (barely below the LVD safety limit for DC) 4-phase 750W boost converter. What next - find a 120V construction vacuum. Not going to order from the USA or Japan due to tight schedule - but quick Googling revealed there exists a complete market for 120V vacuum cleaners and power tools in the UK, so got one from there. And of course, brushed motor vacuum cleaners run from DC just fine, even better than from the AC supply. It was a truly capable solution, with 50cm wide nozzle it picked up quite heavy dirt, gravel etc.

author: Zero999
author_rank: Super Contributor
timestamp: November 30, 2022, 08:49:02 pm
content: 120VDC is actually on the upper limit for SELV. It still needs basic insulation, but not the same precautions as AC of the same voltage..I hate those site transformers. They're big and bulky and probably cause more injuries manual handling, than they save by reducing the shock risk. It's much safer to use 230V and an RCD.

author: james_s
author_rank: Super Contributor
timestamp: November 30, 2022, 10:14:59 pm
content: Quote from: Zero999 on November 30, 2022, 08:49:02 pmI suspect the transformers came along a lot sooner and the regulations just never changed, there's a lot of inertia in that sort of thing. It's a lot easier to make a new law than to get rid of an old one that isn't really needed anymore.

author: AVGresponding
author_rank: Super Contributor
timestamp: November 30, 2022, 10:22:55 pm
content: Quote from: Zero999 on November 30, 2022, 08:49:02 pmYes, but we were talking about AC, not DC. The limit for AC is 50V.

author: Zero999
author_rank: Super Contributor
timestamp: November 30, 2022, 10:30:07 pm
content: Quote from: AVGresponding on November 30, 2022, 10:22:55 pmI know. If you read Siwastaja's post, which I was responding to, you'll find he was using 120V DC.

author: AVGresponding
author_rank: Super Contributor
timestamp: November 30, 2022, 10:41:04 pm
content: Quote from: Zero999 on November 30, 2022, 10:30:07 pmPerhaps the confusion arose from their mistake regarding the nominal voltage of construction site equipment in the UK, and from the fact they are not clear about the actual voltage they are putting through the 110VAC appliance they are using.