odd question... wiring....

helpimcrap · 31 Oct 2010 at 17:15

should a light switch have 3 wires Ilive/neutral/earth) or is 2 (live/neutral) ok as the light doesn't have a 3rd wire/connection.

the live and neutral go into a block with no space for an earth so i'm assuming the light switch is earthed already so the light doesn't need to be?
:confused:

Cocky-Roach · 31 Oct 2010 at 17:17

you should have 2 wires, a permanently live one and a switch wire which is the one that goes to the light, in theory it should have an earth if its got a metal back box, but aslong as its a plastic switch which it will be youll be fine

dal · 31 Oct 2010 at 17:17

should be a earth as well, there should be a connector on the switch which isnt attached to the black block.

JBuk · 31 Oct 2010 at 17:18

as answered there should be an earth

Lopéz · 31 Oct 2010 at 17:20

There should really be an earth unless it is an extremely old install.

If there is no earth do NOT fit metal switches or metal lamps!

helpimcrap · 31 Oct 2010 at 17:20

Addictuk said:
you should have 2 wires, a permanently live one and a switch wire which is the one that goes to the light, in theory it should have an earth if its got a metal back box, but aslong as its a plastic switch which it will be youll be fine

it is plastic and this is my thinking as i would expect an earth but many domestic things don't seem to have it. :confused:

helpimcrap · 31 Oct 2010 at 17:21

Lopéz said:
There should really be an earth unless it is an extremely old install.

from the 80s. old wiring colours too.

Swifty55 · 31 Oct 2010 at 17:21

Is there an earth on the back box?

helpimcrap · 31 Oct 2010 at 17:24

Swifty55 said:
Is there an earth on the back box?

there isn't an earth on the connector box in the light if thats what you mean?

the light works but i haven't left it on for very long as i thought it weird - i admit i'm coming from a car background so everything has an earth lol.

tom_e · 31 Oct 2010 at 17:24

helpimcrap said:
it is plastic and this is my thinking as i would expect an earth but many domestic things don't seem to have it.

A lot of domestic kit is double earthed http://en.wikipedia.org/wiki/Appliance_classes#Class_II

helpimcrap · 31 Oct 2010 at 17:27

tom_e said:
A lot of domestic kit is double earthed http://en.wikipedia.org/wiki/Appliance_classes#Class_II

er ok, so is a light class III? :confused:

Swifty55 · 31 Oct 2010 at 17:34

Light socket should something like that.

Switch should be something like;

If you can see, Live/Neutral go into the back of switch, and the earth connects to the chasis/backbox.

Lopéz · 31 Oct 2010 at 17:39

The switch cable inside the light switch should generally have red, black and earth (if it's an older install) - the earth should go to the back box (and attach to the switch plate if the faceplate is metal)

Or are you talking about at the actual light fitting itself? Some plastic light fittings don't have an earth (so the earth should still be there but disconnected)

helpimcrap · 31 Oct 2010 at 21:21

Lopéz said:
The switch cable inside the light switch should generally have red, black and earth (if it's an older install) - the earth should go to the back box (and attach to the switch plate if the faceplate is metal)

Or are you talking about at the actual light fitting itself? Some plastic light fittings don't have an earth (so the earth should still be there but disconnected)

the actual light fitting itself. :confused:

oh crap... just realised i worded it wrong. its not the switch but the light fitting....

sorry all.

Lethagized · 1 Nov 2010 at 12:56

helpimcrap said:
the actual light fitting itself.

oh crap... just realised i worded it wrong. its not the switch but the light fitting....

sorry all.

What type of light fitting is it? If it's metal, there must be an earth wire connected to it to be safe.

tom_e said:
A lot of domestic kit is double earthed http://en.wikipedia.org/wiki/Appliance_classes#Class_II

You mean double insulated?

Mainly, The only things that require an earth are white goods and anything that has a metallic casing, but some things with a plastic casing such as a shower, kettle or iron also have an earth.