Any Sparkys? Electrical Question

[DR]

Got 2 new light fittings for the lounge - I've got them wired in and they work perfectly - wanted to check something.

They are 2 cable fittings - so live/neutral but they are clear cased cables - one has text on the side of it - is this neutral or live?

Would it not work properly if it was wired incorrectly - aka live on the light fitting to neutral on the lighting ring?

[g8ina]

Yes, it would go bang big time if you wired it wrong !

If you can grab any of the text on the cable it would help ID it. Other than that I have no idea.

[DR]

One strand has text the other doesn't - hence me thinking it's right...

so it's 2 strand - I've wired one in to live, one in to neutral and it works fine...

[DR]

So if you wired live to neutral and neutral to live it wouldn't work and would go pop?

[Funkstar]

It's AC, so getting live and neutral the wrong way round just means that a strand is peaking high when it should be peaking low. Makes no difference for a light and probably most other devices.

DC is different. Applying a positive voltage to the end that is supposed to be grounded can be a very bad thing.

[DR]

It's AC, so getting live and neutral the wrong way round just means that a strand is peaking high when it should be peaking low. Makes no difference for a light and probably most other devices.

DC is different. Applying a positive voltage to the end that is supposed to be grounded can be a very bad thing.

Yep pretty much what a friend who is a sparky has said to me - he just said becareful when changing the bulbs just incase well it's a glass surround so doesn't actually matter that much

They kick ass.....got some of these bulbs in them: http://www.mimime.co/

[TheAnimus]

Well it might fail and you'll be liable when changing a bulb, as your friend probably mentioned.

Its not a case of a 'strand peaking high when it should be low' sorry but that's an odd way of thinking of it.

AC voltage can be thought of as a hot, and a return. Don't touch the hot is a top tip.

Normally with lighting you put the switch in the hot (or live, or phase, or whatever you want to call it) so that when you are changing a bulb the only circuit which isn't broken (switched off) is the return. The return is nothing more than a efficient path to the ground, so is less likely to harm. If you've got your light the wrong way round, rather than the hot been switched off, only the return will have been switched off, so guess what that means if you touch it whilst changing the bulb? The hot will have to return, via you, and you may well have a very bad time.

If you have a tester, it will be worth using it to make sure you've got it the right way round! If you don't they are dirt cheap:
http://www.amazon.co.uk/Black-Spur-S...6002011&sr=8-1
Not even a quid. I always have one of these to make sure that the double check I've done has been sufficent. But then I've been in hospital thanks to an electrocution (which irritatingly wasn't my fault....)

[wasabi]

Personally I'd tape each end of the cable with red on whichever strand I'd have decided is live. Leccy tape is only a quid or so in any DIY shop. Will massively help when someone comes to extend the circuit later or make changes.

[g8ina]

My concern would have been if you had say, 2 light switches in the room, you have to sort of daisy chain to the second switch, and that's where you have the possibility of getting it the wrong way round and the fuses going pop. If its a single fitting to a single switch, then I don't see a problem.

[TheAnimus]

If its a single fitting to a single switch, then I don't see a problem.

If you've not wired the switch yourself, yup.

If you have wired the switch yourself make sure you switch the live.

[peterb]

For a two wire fitting, polarity is irrelevant to the operation of it. From a safety perspective, line should be switched anyway so no part of the fitting is live when the lamp is switched off. (Neutral should be at or near earth potential anyway)

From a safety PoV, if the fitting is bayonet, it doesn't matter which way round it is wired. If it is edison screw, then the screw part should be connected to neutral, the centre contact to line.

All exposed metal parts should normally be earthed. I'm guessing that as these fittings don't have UK colour coded cable, they are imports, in which case they may not meet UK safety standards. That doesn't mean that they are intrinsically dangerous, just that you have to be a little more careful in ensuring that they are connected safely. This is particularly true if it was designed for the US market operating at 115V, where the insulation standards may be less rigorous.

To summarise TheAnimus's post, UK mains supply is not 'floating'. One side, neutral, is connected to earth at the distribution point (substation or distribution transformer) and at the supply side of the consumer unit (and often at many points in between). Line is at (nominally) 230 volts above earth potential, and that is the one that will bite if you touch it - which is why that should be switched, and connections/contacts protected.