Replacing a lightswitch

gam3r

gam3r

gam3r

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So, I decided to replace a few light switches in my house with newer ones which are basically brushed aluminium. The current ones are plastic and when I went to open one up to replace I noticed there was only two wires(black and red) and no earthing wire.

I've read on the slip that came with the switches that they must be earthed as they are metal based - and also the same on the net.

My question is, what can I do from here if I don't have this earthing wire?
 
In my house I believe the metal back box of the switch is earthed so I have put a wire from the switch to the box.
 
If you have no earth at the switch then you can't use metal accessories. It's pretty much that simple.
 
If you have no earth at the switch then you should use plastic switches. Same with lights (but lights are higher up and not usually touched)
Many years ago there was no earth wire in lighting cable. This I guess was to save money.
Now you also might have a conduit system for the lights in which case the steel tube might be earthed (would need to look and test if it is in place)
If all else fails then you really need to get an earth wire down to the switches you want to change to metallic, a 4.0mm cable from the nearest socket will do.

Hope this helps
 
phil-k said:
if there is an earth wire attached to the backing box you are ok, the screws connect the front face to earth
Click to expand...

That's NOT good practice, you should ALWAYS connect a earth loop from the earth terminal in the Metal Back Box to the earth connection on the switch!
Some of the metal parts/box bolts might be coated/treated which could increase resistance! A belt and braces approach is always favoured when working with electrics, especially the CPC/Earth!!

If your back box has no earth then unless you provide one your stuck with double insulated switchs I'm afraid.

/16th Ed. Sparky
 
Good to know ^ I'm sure our switches are earthed via the wire or to the metal box though.

This reminds me of the time I was working on a downstairs switch so I switched the power off on that breaker....forgetting a spur went to the upstairs light :( cutting a live wire is not fun.
 
You may find that your wiring is done using what I would call twin and earth where there is black, red and then a bare copper inside the grey outer sheath, the bare copper being used as earth. Sometimes the bare copper is cut further up and unused. Asuming this is the case it's probably worth checking this has been conected at the light fitting end. If it's simply red and black then it's plastic for you I'm afraid. A pic might help?
 
Not that long really, The final switch was early 2006.

Loads and loads of installations are still in Red and Black.
 
C.R.A.Z.Y said:
That's NOT good practice, you should ALWAYS connect a earth loop from the earth terminal in the Metal Back Box to the earth connection on the switch!
Some of the metal parts/box bolts might be coated/treated which could increase resistance! A belt and braces approach is always favoured when working with electrics, especially the CPC/Earth!!

If your back box has no earth then unless you provide one your stuck with double insulated switchs I'm afraid.

/16th Ed. Sparky
Click to expand...

Might I add though, that no-where in the regs does it state that you should do this. 3.5mm Screws are more than ample for the job.
 
ZG002 said:
Not that long really, The final switch was early 2006.
Loads and loads of installations are still in Red and Black.
Click to expand...

2004... The changeover period was officially april 2004 to april 2006. However anyone buying cable in june 2004 would have got the new colours as it was that quick!

In my house I believe the metal back box of the switch is earthed so I have put a wire from the switch to the box.
Click to expand...

Thats only the case if you *do* have an earth and its already connected to the box, or if its a full steel conduit installation (uncommon in a house)

Yes its as simple as the others have said... no earth at switch = no class 1 metal switches allowed. This also means that your house was wired pre 1966 when the 14th edition came in and required earths to every point, and therefore is probably due for a re-wire!
 
In addition, You are permitted to rely on the m3.5 to earth a recessed K/O from an accessory, but you may not rely on them to earth an accessory from a K/O box.

A short link od 6491x g/y is considered good practice regardless tho
 
Just buy faceplates where the metal facia is totally insulated. I have an old house without earths to switches, and found some lovely metal "screwless" digital touch control faceplates where the metal face clips over the plastic body - totally safe.

Digitals are also much better as you can have 2-way dimming (mine actually allow up to 8-way dimming!).
 
Thanks for all the replies.

Jez said:
Just buy faceplates where the metal facia is totally insulated. I have an old house without earths to switches, and found some lovely metal "screwless" digital touch control faceplates where the metal face clips over the plastic body - totally safe.

Digitals are also much better as you can have 2-way dimming (mine actually allow up to 8-way dimming!).
Click to expand...

My switch has plastic surrounding it, but it still explicitly states that it should be earthed:


20120826125512.jpg

20120826125506.jpg



I'll take a pic of the wiring behind the switch later. I think there may have been a copper wire(not in any sheathing or anything in one of the switches)
(Sorry for the carp pics)
 
Use common sense, does the faceplate touch anything metallic behind it? If it doesnt and it is entirely insulated then just install it and dont worry about it. The idea that metal faceplates must be earthed comes from the fact that a cable could snag or come loose and cause the box or the faceplate to come live, if the bit you touch is fully insulated from these then it is as safe as a plastic switch.
 
Then while installing your live pops out or has a break in it, It happens to touch the metal plate shown, Well that now makes your m3.5 bolts live to the touch, Great idea. Jez the regulations are there for a reason, And that switch needs to be earthed for a reason.

It actually sounds like the op might have a cpc at the switch but it isn't connected. (which in turn means it's like to not be connected at the light either)
 
ZG002 said:
Then while installing your live pops out or has a break in it, It happens to touch the metal plate shown, Well that now makes your m3.5 bolts live to the touch, Great idea. Jez the regulations are there for a reason, And that switch needs to be earthed for a reason.

It actually sounds like the op might have a cpc at the switch but it isn't connected. (which in turn means it's like to not be connected at the light either)
Click to expand...

The faceplate probably doesnt touch the bolts (thanks for clarifying the diameter of them by the way :p)

If the faceplate doesnt touch anything and is entirely insulated then its as safe as a plastic switch, common sense. The regulations are indeed there for a reason, but it doesnt take much to understand that some of them need not be followed to the letter in all cases.
 
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