A shocking discovery

[IanB]

So I found that here in the USA, if you remove the cover plate from a wall outlet there are live metal parts completely exposed where you can touch them. What kind of crazy country is this? At least in Europe the terminal screws are recessed inside plastic surrounds so you can't touch them with your fingers. I'm going to take a picture of an American design so people can see it. I don't think there was any safety review at all...

[Pentium100]

If you take the cover off a Schuko socket, while the screws are recessed, it is still possible to touch the metal parts and shock oneself. Or you can take the lazy way and just insert a couple of nails in the socket - no need to remove the cover for the shock.

I also do not see any problem with that. If the outlet is damaged to the point that it is possible to touch the live wire, you should replace it and if you want to take the cover off, just switch off the power.

[IanB]

Right, so my next job coming up is to make a map of my house and label each wall outlet, then find out which outlets are connected to which circuit breaker. Someone stuck labels on the breaker panel, but there may be some fuzziness about exactly which outlets are covered. I want to be more precise. I suppose I will have to switch off each breaker one by one and then go around the house with a voltage detector to see which outlets got disconnected.

In the UK it is much simpler. There are basically four ring mains: downstairs power, downstairs lighting, upstairs power, upstairs lighting; then extra circuits for cooker, water heater, garage/outside, and maybe electric shower or electric heating if installed. Luckily tumble driers plug into a standard 13 A wall socket and so there are no special circuits for that. And of course nobody needs air conditioning so there are no circuits for that either.

[david77]

If you take the cover off a Schuko socket, while the screws are recessed, it is still possible to touch the metal parts and shock oneself.

This is only true for older Schuko sockets/switches. The contacts on newer parts are designed to be fingerproof even with the covers removed.

[Pentium100]

Right, so my next job coming up is to make a map of my house and label each wall outlet, then find out which outlets are connected to which circuit breaker. Someone stuck labels on the breaker panel, but there may be some fuzziness about exactly which outlets are covered. I want to be more precise. I suppose I will have to switch off each breaker one by one and then go around the house with a voltage detector to see which outlets got disconnected.

Plug in a radio, turn it on, set the volume so you hear it when you are next to the circuit breakers. Turn the breakers off one by one until the music stops.

There are a lot of circuit breakers in my house, but they are labeled and I always check the voltage before and after taking the cover off.

This is only true for older Schuko sockets/switches. The contacts on newer parts are designed to be fingerproof even with the covers removed.

Soviet sockets are also dangerous with the cover off. Also, who the hell works on an outlet without turning off the power? As for accidental shocks, taking the cover off requires more work than putting a couple of nails in.

[Psi]

I think most of the wall plates available in NZ are recessed plastic but the original ones (which are in millions of homes) are all exposed at the back. I'm not aware of any law about new installations requiring the modem recessed type though.

I think it was something PDL and other companies just did on their own when designing new ranges of plates.

As i understand it, removing a wallplate is not something a typical person is supposed to be doing.

[slateraptor]

So I found that here in the USA, if you remove the cover plate from a wall outlet there are live metal parts completely exposed where you can touch them. What kind of crazy country is this? At least in Europe the terminal screws are recessed inside plastic surrounds so you can't touch them with your fingers. I'm going to take a picture of an American design so people can see it. I don't think there was any safety review at all...

What's so crazy about that? You shouldn't be handling live wires to begin with unless you're either qualified to do so or absolutely certain you know what you're doing, and a good nasty shock would significantly reduce the probability of any future repeat occurrences. By your argument, engineers ought to insulate every square inch of exposed metal on a power supply's primary to deter buffoons who decide to take the screws off some device's enclosure. Perhaps Americans aren't quite the liability that you suggest. =\

[IanB]

As i understand it, removing a wallplate is not something a typical person is supposed to be doing.

If safety rules were about what a typical person is not supposed to be doing, then most of the safety rules in existence would be unnecessary. Nobody should be doing anything dangerous.

But here's the story with wall outlets in the USA.

This is what the fixture looks like in the wall (cover removed with one simple screw):



And close up, here is the fitting outside the wall:



All the exposed metal parts on the side are live. The opposite side is exactly the same for the neutral wire.

Here is a natural way to grasp it when removing it from the wall. Note how the fingers naturally fall on the live metal terminals. I am sure nobody has been required to produce any kind of safety case for this design.



(It looks like the old fitting in the wall is a tiny bit safer than the new replacement...go figure.)

[AntiProtonBoy]

^ that wall outlet does seem to be a fairly poor design.

Also, who the hell works on an outlet without turning off the power? As for accidental shocks, taking the cover off requires more work than putting a couple of nails in.

Pro electricians work on live wires all the time. I did on several occasions when repairing gas stoves.

[Monkeh]

American sockets leave a lot to be desired..

In the UK it is much simpler. There are basically four ring mains: downstairs power, downstairs lighting, upstairs power, upstairs lighting; then extra circuits for cooker, water heater, garage/outside, and maybe electric shower or electric heating if installed. Luckily tumble driers plug into a standard 13 A wall socket and so there are no special circuits for that. And of course nobody needs air conditioning so there are no circuits for that either.

That's a very narrow view of domestic installations. Equipment such as tumble driers, washing machines, and the like should be on their own circuit or circuits in a properly designed installation. Also, none of those are 'ring mains', and only two are likely to be ring finals.

[free_electron]

fire your electrician !

American style plugs and switches are supposed to be taped around with electricans tape after the terminals have tightened and just prior to pushing them in their wall boxes ! but it is not mandatory, only recommended....

When i bought my house last year i replaced ALL outlets and switches ( they still had those ugly tumbler switches even though the house is only 8 years old )
I used Cooper for all fixtures ( the charcoal style paddles with a silver trim ). taped all of them.

What is more applaing is the fact that almost none of the american outlets have child proof sockets. you can just poke whatever in the holes. The coopers have a piece of plastic that refuses to budge unless you poke the plug exactly right into the socket. (Tamper resistant Outlet )

[Pentium100]

Pro electricians work on live wires all the time. I did on several occasions when repairing gas stoves.

Well, until you come across a place that was miswired (so the wire that's supposed to be neutral is actually live) or somthing causes you to touch the live and neutral wired at the same time.

The way I see it, there is no real reason not to turn off the power when working on an outlet (or a switch). On the other hand, I may poke around in a device with the power on in order to repair it (no way to measure the voltages if the device is turned off).

[Randall W. Lott]

I always turn the breaker off when working on an outlet.  There are too many things that could go wrong.  Better be safe and make a little extra effort.

All of the outlets in my home are exactly like the one you showed.  There is no tape.

When I was younger, I tried to pry the duplex outlet out of the box with a slotted screwdriver.  I learned that the surrounding areas, such as the screw posts, can hurt.  Granted, my house was built in the 1970's.

[G7PSK]

I have got one of those Levinton socket in front of me as I type the inclosed instructions do not mention winding tape arround the terminals It does refer to putting the "HOT" Black wire under the brass screws the "NEUTRAL" white wire under the silver screw and the 2Ground" Green or bare wire under the green screw. The cover is fixed with two screws. When fitted into the pattres there is not enough room for most adults to insert their fingers.

There are many instances where if covers are removed you can access lethal voltages, when I remove the terminal covers on some of the power plants I can get both hands inside where there are six terminals with 415 volts at over 100 amps each, I once dropped a 19 ring spanner into the box when the plant was running there was a blue flash and the spanner was melted with only slight marking on the 12mm brass studs.

What Is required is a world wide standard for voltage frequency and plug design.

[wkb]

What Is required is a world wide standard for voltage frequency and plug design.

Yes.  Quite similar to world peace.  And about as likely to happen 

[IanB]

And one more thing: are you meant to mount the socket with the ground pin "up" or "down" (as pictured)?

I have some low profile plugs where the cable falls downward with the ground pin below, and others where the cable expects the plug to be inserted in the opposite orientation.

The most common convention seems to expect the ground pin downwards, but the manufacturer's installation diagram suggests the opposite.

I wish people would make up their minds.

[Bored@Work]

The part I don't understand is why you expect isolation? You had just removed the isolation, the face plate. You then sticked your fingers inside a thing that you know is connected to mains. Why do you expect a second isolation?

It is not different from other mains powered things. You open the enclosure, you no longer have isolation from mains Would you just stick a finger in a random mains powered device?

[IanB]

The part I don't understand is why you expect isolation? You had just removed the isolation, the face plate. You then sticked your fingers inside a thing that you know is connected to mains. Why do you expect a second isolation?

Because it would be a better design that way?

It is not different from other mains powered things. You open the enclosure, you no longer have isolation from mains Would you just stick a finger in a random mains powered device?

No, I don't tend to go sticking my fingers in places with mains voltages present. But at the same time standards of safety should consider avoiding or removing reasonably foreseeable hazards. The face plate here is a very weak and flimsy cover. Double insulation is not a lot to ask for in the design of such a fitting.

Consider tear downs of older gear on this forum. When people take the cover off a device you hear comments like "that's clearly an older design, those exposed mains terminals inside would not be permitted today". Standards change.

[Psi]

I take it the point was 110V ?

110v isn't quite as dangerous as 240v, so they probably don't put such an emphasis on safety that we do with 240v in NZ/AU

[Neilm]

What Is required is a world wide standard for voltage frequency and plug design.

http://xkcd.com/927/

[wkb]

The part I don't understand is why you expect isolation? You had just removed the isolation, the face plate. You then sticked your fingers inside a thing that you know is connected to mains. Why do you expect a second isolation?

Because it would be a better design that way?

It is not different from other mains powered things. You open the enclosure, you no longer have isolation from mains Would you just stick a finger in a random mains powered device?

No, I don't tend to go sticking my fingers in places with mains voltages present. But at the same time standards of safety should consider avoiding or removing reasonably foreseeable hazards. The face plate here is a very weak and flimsy cover. Double insulation is not a lot to ask for in the design of such a fitting.

Consider tear downs of older gear on this forum. When people take the cover off a device you hear comments like "that's clearly an older design, those exposed mains terminals inside would not be permitted today". Standards change.

You mean: the world has changed to have more than the desired number of lawyers now?  The proverbial: Can we claim damages from the vendor/his producer/his pet dog?

In other words: trained people should know what they are doing.  It is plain silly to work on live circuits if you very well know how you can prevent doing so. 

[Bored@Work]

[billclay]

So I found that here in the USA, if you remove the cover plate from a wall outlet there are live metal parts completely exposed where you can touch them. What kind of crazy country is this? At least in Europe the terminal screws are recessed inside plastic surrounds so you can't touch them with your fingers. I'm going to take a picture of an American design so people can see it. I don't think there was any safety review at all...

The "safety" was the cover and the box protecting the outlet.  You removed the safety.

Would you open the cover on a plugged in power supply that was running (maybe with even a label that says "DANGER: HIGH VOLTAGE INSIDE") and touch the exposed capacitor terminals or transformer connections?  No, you'd unplug the device and de-energize the caps first.

[G7PSK]

Most of the British wall sockets the front cover plate is integral with the rest of the unit it is only with the industrial metal clad units that the cover is separate from the socket. If you pull the face-plate out the wires come out attached.

[wkb]

So I found that here in the USA, if you remove the cover plate from a wall outlet there are live metal parts completely exposed where you can touch them. What kind of crazy country is this? At least in Europe the terminal screws are recessed inside plastic surrounds so you can't touch them with your fingers. I'm going to take a picture of an American design so people can see it. I don't think there was any safety review at all...

The "safety" was the cover and the box protecting the outlet.  You removed the safety.

Would you open the cover on a plugged in power supply that was running (maybe with even a label that says "DANGER: HIGH VOLTAGE INSIDE") and touch the exposed capacitor terminals or transformer connections?  No, you'd unplug the device and de-energize the caps first.

And if you didn't you'd be granted a Darwin Award     [http://www.darwinawards.com/]