This house was built in 1940, and wired with an early form of Romex...Cloth wrapper, no ground wire. Apart from the water bond, there is no grounding. All receptacles are two-prong. The only bath recep is part of the light over the mirror. The main room, with almost fifty feet of perimeter, has exactly one receptacle. The only kitchen receptacle shares a single-gang box with a switch for the exhaust fan.
It sure is a different world over there! The whole thread is here:
The comment I liked was the one which said something along the lines of "The hospital where I worked had these things, installed in 1933. They were replaced when the wards were remodelled in 1995".
Those bods don't seem to like their "thermomagnetic breakers". In what way do their breakers differ from our modern MCBs?
Exactly, nail on head. 1930s wiring is common place over there _today_ in 2005. Having no earth anywhere on your presmises is considered normal, numerous old installs are like that. I've only once ever seen anything that ancient over here.
I dont know, but I know enough about merican lectrics to know their kit is generally of way lower quality than here. For example the standard insulator on bulb holders is a piece of card, and the standard socket cable connector is a flat spring, not a screw connection. So I wouldnt be surprised if their mcbs were slow, unreliable, or overheated.
My impression from reading US NG's is that their breakers are not unknown for burning out, falling to bits, drifting trip values, etc. which I've never come across with ours. If you pick the things up in Home Depot and look at them, they just don't feel anything like the same quality as ours either. The funny thing is some of them are same manufacturers as the EU ones, but obviously built to different standards (and possibly price -- I don't recall how that compared with ours).
Many of their older breakers are thermal only, and don't have the fast fault current response ours do. I don't know if all their current breakers have the magnetic trip component.
If you get to go to the US, a stroll through the electrical section of Home Depot is really quite frightening. However, you'll find many more things stocked which you won't find stocked in B&Q and would be special order only from even a UK electrical wholesaler.
They have thermal trip only. They cost about 1.3p to make in some sweatshop and are as reliable as a clingfilm condom.
The US electrical system is simply unsafe compared to the rest of the world. It largely comes down to:
Lower voltage. 110V is much more dangerous than 230V. This isn't obvious to the non-technical, but the US went with "common sense" (aka thick people's prejudices) rather than sound scientific analysis. The basic issue is that very few people die of electrocution, whilst loads of people die from electrical fires. The electrical fires largely stem from high currents. If you halve the voltage, you double the current.
The high voltage has other safety benefits, too. For example, during an earth fault, the higher voltage leads to much higher current flow. An overcurrent safety device is, thus, much more effective, leading to much more rapid disconnect of the circuit.
Some numbers. Take a hypothetical circuit rated for a bit over 3kW. In the US, this would be 110V, 30A. If the breaker requires 5x current to trip immediately, this requires an earth impedence of 0.73 ohm right back to the substation. Of course, most US circuit breakers are thermal anyway, so trip is never immediate. With less than about 0.73 ohm, it will take much longer to trip (or perhaps it never trips, if the earth loop impedence is too high). A slightly higher energy circuit in the UK would be 230V, 15A. The required earth impedence is now 3.8 ohms. This is extremely easy to achieve, unlike the 0.73 ohm, which might even be impossible.
Another effect of the low voltage is that "respect" for electricity is lower. The lower voltage leads to lower quality insulation on fittings, cheaper parts and a blase attitude of users to electrocution. The result of this is that the US actually has a higher electrocution death rate per capita than the UK, despite the lower voltage! When you compare the incidence of electrical fires, the differences become much more scary.
Other differences in the US:
Low quality cables that have arcing failure modes, leading to fires.
Use of wirenuts.
Combination of neutral to earth (i.e. effectively TN-C earthing) leading to electrocution in the event of polarisation swap, or some open circuit conditions. TN-C earthing in banned in Europe, except in special (non-domestic) cases.
Provision of socket outlets in bathrooms, so users dry their hair in the bath.
Actually, the choice of mains voltage on either side of the pond was not decided on safety grounds. The safety issues were largely unknown at the time.
and quadruple the overheating effect.
You missed:
the crap quality of their socket outlets, responsible for many fires.
building regulations which hinder people modernising their wiring, so extremely old wiring still in use is very much more common. Oh hang on, scratch that one, we just introduced the same regulations here.
Actually I included that under the low voltage section, as it is the low voltage that makes them think they can get away with it, although I suspect it is just a cheap as possible, don't care attitude, really.
Even with Prat P we dont rent out apartments and blocks all wired a la
1930s in 2005... its either legal over there or not enforced. I suspect legal, given the litigius society and wide spread of 30s electrics, waaaaaaaay past their scrap by date. What people often dont stop to think is that a typical 1930s install today would even fail a /1930s/ safety inspection, due to deterioration and additions leading to overloading.
No it is not legal. On a large Middle East US site I was at, it was all conduit and 1930s electrics. In plants rooms not a bit of mineral insulated cable to be seen (the norm in Europe). I asked why mineral insulated cable had not been used, and none of them had heard of it. One knowledgeable man said mineral insulated is used in the US, but infrequently because of cost. This I found strange as installing metal conduit is not cheap. The merits of conduit were given to me and how cheap is just to pull though extra wires or to replace. I asked them how often do you replace wires? Slapping pyro around the walls is not that expensive in comparison. The US appears habitual in many aspects, although they did abandon fuses to a large extent.
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He might not have been talking about the same stuff..
Visiting a company Boston I did some work for, I noticed an electronic service engineer colleague up a pair of step ladders working above the suspended ceiling. He explained he was also a state registered electrician so they had him do the electrical odd jobs around the factory. He was installing a length of flexible metal sheathed cable which was corrugated like flexible copper tap connectors. He went on to say that this stuff can be used anywhere without restriction, didn't have to be fastened down, and any surplus could just be just thrown into the void in the suspended ceiling. I got the impression BICBW it came pre-terminated and was sold in standard lengths, I suppose that might make it expensive.
I visit Lowes and WalMart on most trips, and on the last trip came across shelves and shelves of shotgun cartridges at WalMart, which was a bit startling.
I have an American "domestic electrical diy handbook" and it's fascinating. I'd never seen a wirenut before I read that.
Theres a famous picture of an American extension lead made by someone who remarkably survived. He put 2 sockets into a cut open shampoo bottle and taped it all up. The idea was it would float. Yep, float, in his pool. Appaerntly it was so he could watch tv while in the pool.
I replaced the garbage disposal in my mother's house (in Pennsylvania) a few months ago.
Good things; Huge individual circuit breaker panel easily available in the kitchen, so no grovelling under the stairs and having to switch off an entire ring to isolate the garbage disposal.
Bad things; The new garbage disposal came without any connectors, cable grip or grommet. Just a hole in the case with 2 wires poking out of it. Fortunately, I managed to scavenge the bits I needed from the old one, including the wire nuts.
Garbage disposal! Useless devices IMHO; today we too compost. Although the heap sometimes freezes during the winter. Heap also produces worms for trout fishing. Worms flourish on discarded banana skins, potato peelings, other kitchen discards of the non-meat variety along with last year's raked leaves. Recall semi amusing event: About 48 years ago someone gave us a brand new under sink mounting 'Garbage Disposal' unit. It had about a third HP 115 volt 60 Hertz motor! Installed it in the 35 by 8 foot house trailer we then lived in. Worked fine until the sewer line blocked. Not knowing line was blocked, or perhaps in an attempt to blow the obstruction down the pipe towards the septic tank, I forget which, I switched it on, fully loaded with water and with the tap running! Result was a jet of water and other 'unmentionable stuff' straight up out of the vent pipe in roof of the trailer. A neighbour said "It WAS quite sight". So was the clean up! Ever try cleaning sprayed 'cr*p' off the aluminium siding, roof and windows of a trailer (caravan)?
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