Don't Assume It's Been Done Right Because TIJ

[Wage Slave]

The hammer was taking earlier about how having been once bitten by electricity one tends to be far more careful even to the point of pedantry. Here's an example of why you need to be like that:

I had to replace a bathroom ventilator fan recently. It was working but noisy and no amount of cleaning and lubrication was going to fix the fact the bearings were shot. It also didn't really move enough air meaning the place got pretty steamed up and not in a good way. So, usual overcomplicated puzzle to get the thing out complete with the obligatory corroded securing screw just to make sure it takes that bit longer. I was short of time so just snipped the power leads - Hey it's switched off right? Then, of course the replacement unit from the same company had a completely different mounting design and a redesigned outlet which meant that the exhaust piping had to be cut by about an inch to fit.

By the time I had done all this, mounted the support/outlet, re-assembled the exhaust and drilled new holes for the securing screws other duties called so I had to leave it until well after dark. OK so, I need light to work and I shouldn't have to cut all power to the bathroom right? After all, it is switched off isn't it? Yes, it is, so I stripped the active conductor. Experience has taught me to assume that things are live unless you tested them. But I couldn't test it until I had stripped it so I stripped it very carefully with a plastic handled knife. And then put a voltage tester on the bare wire.

Sure enough it was hot. The cowboys who did the bathroom for Sexy House had only gone and wired the switch to neutral leg of the supply. Wankers.

[Yokohammer]

And in a room with a primary function that involves significant quantities of water ...

[Coligny]

To their defense... i don't think Japan differentiate between live an neutral...

And in the clinic... All the plugs with an earth connection have the earth pin wired directly to the nearest wall stud... Wood wall stud...

[Wage Slave]

To their defense... i don't think Japan differentiate between live an neutral...

Agreed, they seem to regard them as interchangeable for most practical purposes. Even though the sockets are keyed, the plugs are carefully designed to defeat the key.

And in the clinic... All the plugs with an earth connection have the earth pin wired directly to the nearest wall stud... Wood wall stud...

Is this really true or are you just entertaining us again? Anyway, it's just as well there is only 100V to play with and that RCDs are dutifully standard is all I can say.

[Wage Slave]

And in a room with a primary function that involves significant quantities of water ...

Exactly. In a bathroom, of all places, you wire a switch that doesn't isolate the power. Wankers.

[Russell]

To their defense... i don't think Japan differentiate between live an neutral...

And in the clinic... All the plugs with an earth connection have the earth pin wired directly to the nearest wall stud... Wood wall stud...

Is there a way to test whether earth is really earth by some kind of electric measuring device?

[Yokohammer]

To their defense... i don't think Japan differentiate between live an neutral...

And in the clinic... All the plugs with an earth connection have the earth pin wired directly to the nearest wall stud... Wood wall stud...

Is there a way to test whether earth is really earth by some kind of electric measuring device?

Quite easy with any multimeter that has a resistance measuring function.

Check the resistance between the supposed earth and a known earth (a metal cold water pipe is a good choice ... you just have to know that the metal part extends into the ground. If you're feeling energetic you could also pound a copper earth rod into the ground somewhere). The resistance should be very low.

[Wage Slave]

To their defense... i don't think Japan differentiate between live an neutral...

And in the clinic... All the plugs with an earth connection have the earth pin wired directly to the nearest wall stud... Wood wall stud...

Is there a way to test whether earth is really earth by some kind of electric measuring device?

Good point. Especially since I have often see earths for 200V ac units which are no more than 6 incches of rod driven into the dry soil under the eaves of the house. I'm used to seeing earths bonded to a metal mains water pipe. Never seen here. To test it you need an earth resistance meter like this one:

http://www.megger.com/uk/products/ProductDetails.php?ID=881&Description=

I actually hate to think what the earth in my place is now. I have a nasty feeling the mains water to the property is via plastic pipe. Have they just driven a little stake into that nice dry earth under the house?

[Wage Slave]

Quite easy with any multimeter that has a resistance measuring function.

Check the resistance between the supposed earth and a known earth (a metal cold water pipe is a good choice ... you just have to know that the metal part extends into the ground. If you're feeling energetic you could also pound a copper earth rod into the ground somewhere). The resistance should be very low.

Are you sure about that? I thought testing for ground needed a higher voltage than the 9v or so a multimeter can provide. It's a bit how they are useless for testing high voltage capacitors. 9V just isn't enough to kick open the door so to speak.

[Yokohammer]

Copper earthing rods or plates actually work pretty well in japan, because the ground is almost always moist just a few inches under the surface. Not so much in the Sahara.

[Yokohammer]

Quite easy with any multimeter that has a resistance measuring function.

Check the resistance between the supposed earth and a known earth (a metal cold water pipe is a good choice ... you just have to know that the metal part extends into the ground. If you're feeling energetic you could also pound a copper earth rod into the ground somewhere). The resistance should be very low.

Are you sure about that? I thought testing for ground needed a higher voltage than the 9v or so a multimeter can provide. It's a bit how they are useless for testing high voltage capacitors. 9V just isn't enough to kick open the door so to speak.

I've done it successfully a couple of times (over the relatively short distances of an average household).

Try it and see.

EDIT: Just don't expect to see 0 ohms ... maybe a couple hundred. Or thousand ... I don't remember. But basically, if you see a circuit, you have a ground.

[Wage Slave]

Quite easy with any multimeter that has a resistance measuring function.

Check the resistance between the supposed earth and a known earth (a metal cold water pipe is a good choice ... you just have to know that the metal part extends into the ground. If you're feeling energetic you could also pound a copper earth rod into the ground somewhere). The resistance should be very low.

Are you sure about that? I thought testing for ground needed a higher voltage than the 9v or so a multimeter can provide. It's a bit how they are useless for testing high voltage capacitors. 9V just isn't enough to kick open the door so to speak.

I've done it successfully a couple of times (over the relatively short distances of an average household).

Try it and see.

EDIT: Just don't expect to see 0 ohms ... maybe a couple hundred. Or thousand ... I don't remember. But basically, if you see a circuit, you have a ground.

I will try it now.

[Yokohammer]

I will try it now.

You have far more energy than I do ...

Another edit: while you're at it, try measuring from the hot side of an AC outlet to a cold water pipe. (Er, set your meter to AC volts, of course).

[Wage Slave]

About 800 ohms. That's re-assuring I suppose given it is only 9V.

[Wage Slave]

I will try it now.

You have far more energy than I do ...

Just happen to have a rod for a radio set earth and a mains earth already wired to the same point. I was experimenting with which worked better.

[Yokohammer]

About 800 ohms. That's re-assuring I suppose given it is only 9V.

Sounds about right.
A standard multimeter will only give sort of agricultural-tolerance precision, but at least you know you have some sort of ground.

[Coligny]

Is this really true or are you just entertaining us again? Anyway, it's just as well there is only 100V to play with and that RCDs are dutifully standard is all I can say.

Swears, first noticed in the former newborn nurserie which have drywalls. For concreted walls rooms the earth is plugged into fuckyou instead... A bit of green wire, core not even exposed on the free end...

[Wage Slave]

About 800 ohms. That's re-assuring I suppose given it is only 9V.

Sounds about right.
A standard multimeter will only give sort of agricultural-tolerance precision, but at least you know you have some sort of ground.

True. Nice to know.

Now I think about it why aren't toaster ovens earthed? They have a metal case.

[Yokohammer]

Now I think about it why aren't toaster ovens earthed? They have a metal case.

Be careful with imported kitchen appliances. In the past (like a couple of decades ago) I found some in which the casing was stupidly "earthed" to one side of the two-prong Japanese plug. Probably the doofus that was importing the things assumed that was the way to rewire from a three-wire plug. Of course that means that if you have the plug in the wrong way (and how would you know?) the case of your toaster is hot. So touch your water tap with one hand and the toaster with the other, and you get a very nasty surprise.

I hope that sort of stupidity doesn't happen any more, but you never know. Might be worthwhile using your meter to measure AC between any exposed metal appliance casings in your kitchen and the cold water tap.

[Wage Slave]

Another edit: while you're at it, try measuring from the hot side of an AC outlet to a cold water pipe. (Er, set your meter to AC volts, of course).

100.4V and about half a volt from neutral to the metal pipe. Neutral floating half a volt over earth doesn't concern me.

[yanpa]

To their defense... i don't think Japan differentiate between live an neutral...

Agreed, they seem to regard them as interchangeable for most practical purposes. Even though the sockets are keyed, the plugs are carefully designed to defeat the key.

Having been brought up on the UK's stingent "bRown for right, bLue for left" system, I was bemused when I tried to attach a German plug to my hairdryer as the plug ("Schuko") can be inserted either way in the socket.

I am guessing the UK is particularly paranoid about these things because the fuse is in the plug, not the mains circuitry?

[Wage Slave]

Might be worthwhile using your meter to measure AC between any exposed metal appliance casings in your kitchen and the cold water tap.

I'll do that quickly when I get the kitchen to myself for a few minutes. Can't hurt and only takes a few seconds. Except I'll use the mains earth because the water supply was rerun recently and they used plastic pipe just laid on the ground under the house. Honestly what happened to plumbers doing proper things like soldering, pipe bending, cutting threads and such? Now they just lay plastic hosepipe.

[Yokohammer]

I am guessing the UK is particularly paranoid about these things because the fuse is in the plug, not the mains circuitry?

Also because they're dealing with 230V (innit?) rather than 100.

230V will kill you deader than 100V ... no, wait, that's not right ...
230V is a lot more likely to kill you than 100V, although 100V will do it under the right conditions.

[yanpa]

I am guessing the UK is particularly paranoid about these things because the fuse is in the plug, not the mains circuitry?

Also because they're dealing with 230V (innit?) rather than 100.

230V will kill you deader than 100V ... no, wait, that's not right ...
230V is a lot more likely to kill you than 100V, although 100V will do it under the right conditions.

Indeed... but Germany is also 220~240v and there it is evidently OK to place bog-standard wall-mounted sockets very close to a bathroom sink.

[Yokohammer]

Indeed... but Germany is also 220~240v and there it is evidently OK to place bog-standard wall-mounted sockets very close to a bathroom sink.

Ah ... must be a Teutonic death wish thing then.

[wuchan]

silly gaijin.

When shit breaks we build a new house.

[Wage Slave]

I am guessing the UK is particularly paranoid about these things because the fuse is in the plug, not the mains circuitry?

You see! Electricity is interesting! That's not the rationale for being strict about live and neutral. The fuse in the plug was meant to protect the lead to the appliance and the appliance itself from being exposed to too much current and catching fire or something like that. The fuse at the the fusebox was to protect the wires in the wall from the same. The theory was that a small appliance could go faulty and start drawing (say) 10 amps instead of 2 amps and that would cause it to melt and burn. Meanwhile the 13 amp fuse at the fusebox was still happy to supply 10 amps because the mains wiring was happy with that load.

So, there was supposed to be a suitable fuse in the plug to protect the appliance that it was attached to. It all failed miserably because manufacturers were not required to fit a plug and fuse to the appliances they sold. Hence, it was left to the consumer to go and buy a plug and fit it. The plugs were invariably supplied with a 13 amp fuse because it was easier that way and few people ever understood or bothered with buying the correct fuse and fitting it. As an added bonus, vast numbers of plugs were shockingly badly fitted by know nothing punters.

As for being strict about live and neutral on plugs goes, it very often doesn't matter but when it does matter it matters a lot. Usually it is when there is another wiring fault in the plug as in the example hammer gave. It is far from unknown for neutral and earth to be transposed (see the nonsense in the paragraph above) and the appliance will, of course, work fine. There are also certain older radios that aren't isolated from the mains and so live and neutral being transposed will result in the internal chassis becoming live whilst otherwise operating normally. That shouldn't be a problem under normal circumstances but children and others sometimes fish inside the air vents of cabinets with knives and stupid things like that. It's just better to have these things under control.

[yanpa]

Indeed... but Germany is also 220~240v and there it is evidently OK to place bog-standard wall-mounted sockets very close to a bathroom sink.

Ah ... must be a Teutonic death wish thing then.

That goes pretty much for all of Europe apart from the UK...

[Wage Slave]

Indeed... but Germany is also 220~240v and there it is evidently OK to place bog-standard wall-mounted sockets very close to a bathroom sink.

Ah ... must be a Teutonic death wish thing then.

That goes pretty much for all of Europe apart from the UK...

Yes, it does. Same goes for wall mounted light switches instead of ceiling mounted string actuated switches as in the UK. Wet hand/water + bare feet + 230V@13 amps = hazard according to UK thinking. And it does too especially if there is no RCD in place, which was also standard in the UK.

[kurogane]

I found out the hard way just how live UK sockets are when I brushed my wet from washing up hands past the kitchen wall socket to reach for the toaster. F'in hell. Figgered out why they have switches then, let me tell you Kevin!

Anyways, I am gigging on how I can understand virtually every word and explanation and still have no clue what you guys are on about. Great DIY/Tool Porn.