Metal ceiling rose and light switch metal face plate

[ALMcKINNON]

I've spent a few hours trawling through past posts for an answer to this query but to no avail.

I'm currently replacing a ceiling rose with a one of those Maestro removable ceiling roses. The missus is keen on fitting a light switch with a brass face plate to match this.

I've looked at the current wiring to the ceiling rose and this seems ok (judging by wiring diagrams in the help section of this forum). There are two (what I think are) twin and earth cables running to the ceiling rose(each is a cable with grey outer sheath containing one red, one black and one bare).

My first question is whether or not these are actually T&E? If so, is the bare wire the earth, and if so why is the earth wire bare? I though earth wire was always sheathed in green/yellow?

My concern regarding the earth is that this bare (earth?) wire is not connected to the current ceiling rose. As I am fitting a metal rose I would like to make sure it is properly earthed.

The second part of the question relates to the light switch face plate. There are actually two separate switches (at different locations) controlling the same light. I've noted the colours of the wires at the back of one of the current light switches - 1black, 1 blue, 2 red and 1 yellow. I think I understand this from a diagram found in the help section. The problem is there does not appear to be an earth wire to this switch. I haven't investigated other switch yet but I'm assuming it is probably the same.

From reading other posts I understand that the new metal face plate light switch should be earthed. Should I replace the current cable running from the switch to the light with a cable which includes an earth wire? If so, can I connect this earth to the bare (earth?) wire in the T&E cable of the lighting circuit. Also, if I am earthing the face plate of the light switch, do I also need to earth the metal box behind the light switch (this doesn't appear to be earthed either)?

 

[Adam_151]

There are two (what I think are) twin and earth cables running to the ceiling rose(each is a cable with grey outer sheath containing one red, one black and one bare).

My first question is whether or not these are actually T&E?

Yup

If so, is the bare wire the earth, and if so why is the earth wire bare? I though earth wire was always sheathed in green/yellow?

Yup, and it should be when teminated... http://www.tlc-direct.co.uk/Products/CAGS3slash10.html

My concern regarding the earth is that this bare (earth?) wire is not connected to the current ceiling rose. As I am fitting a metal rose I would like to make sure it is properly earthed.

Was it connected to a choc block or 'earth holding point' in the rose, if not then its should have been, and if there were more than there, then them being not connected means the rest of the circuit is without an earth, which is dangerous, you should verify that you actually have an earth connection that goes to earth and that the same trick hasn't been pulled upstream on the lighting circuit

The problem is there does not appear to be an earth wire to this switch. I haven't investigated other switch yet but I'm assuming it is probably the same. From reading other posts I understand that the new metal face plate light switch should be earthed. Should I replace the current cable running from the switch to the light with a cable which includes an earth wire?

It most likely already has an earth, but its probably been cut back, look closer, as before you should verify that it actually goes somewhere at the other end

Also, if I am earthing the face plate of the light switch, do I also need to earth the metal box behind the light switch (this doesn't appear to be earthed either)?

It should have been earthed before unless you had nylon screws in it (metal ones are an exposed conductive part and should be earthed), the answer to your question is that as long as the box as one fixed lug then its not strictly neccessary, but good practice is to fit a link to the box

Edit: some proof-reading corrections to a quickly typed post

 

[ban-all-sheds]

My first question is whether or not these are actually T&E? If so, is the bare wire the earth, and if so why is the earth wire bare? I though earth wire was always sheathed in green/yellow?

The earth in T&E cables is never sheathed. You sheath the bit that you expose yourself.

My concern regarding the earth is that this bare (earth?) wire is not connected to the current ceiling rose. As I am fitting a metal rose I would like to make sure it is properly earthed.

It should have been connected - there is an earth terminal in the rose for it.

The second part of the question relates to the light switch face plate. There are actually two separate switches (at different locations) controlling the same light. I've noted the colours of the wires at the back of one of the current light switches - 1black, 1 blue, 2 red and 1 yellow. I think I understand this from a diagram found in the help section. The problem is there does not appear to be an earth wire to this switch. I haven't investigated other switch yet but I'm assuming it is probably the same.

The cables will have an earth core, but it may have been cut back in the past by some numpty.

From reading other posts I understand that the new metal face plate light switch should be earthed.

Oh yes.

Should I replace the current cable running from the switch to the light with a cable which includes an earth wire?

Yes, if you can't get at the existing earth cores. (and you should replace both cables, not just the switch drop)

If so, can I connect this earth to the bare (earth?) wire in the T&E cable of the lighting circuit.

Not only can, but must.

The other thing you should do, you'll be distressed to hear, is to get an electrician to check the continuity of the earthing in your lighting circuit. If it's been buggered about with in one place by a numpty, who knows what else he's done elsewhere - you might replace that cable, and thing you've earthed your switch OK, when in fact you haven't...

Also, if I am earthing the face plate of the light switch, do I also need to earth the metal box behind the light switch (this doesn't appear to be earthed either)?

The regs say that if one of the lugs is fixed then you don't need to run an earth from the switch to the box, but most people think it is good practice to do so.



Damn - 2nd place again...

 

[ALMcKINNON]

Thanks very much for your speedy responses.

So, as I understand it, I need to check if the bare wire to the ceiling rose (and all other ceiling roses around the house) is grounded.

Ban-all-sheds, you said that I'd need an electrician for that. Is that absolutely necessary or can I check myself using a multimeter/continuity meter?

Thanks again.

 

[ban-all-sheds]

You can DIY, provided you have a meter that will read low enough, which ordinary multimeters will not - you need to be able to measure down to 0.2 ohms with a resolution of 0.01 ohms....

 

[Adam_151]

You can DIY, provided you have a meter that will read low enough, which ordinary multimeters will not - you need to be able to measure down to 0.2 ohms with a resolution of 0.01 ohms....

Although if he just wanted to confirm that a continious conductor existed as opposed to getting a definative R1+R2 figure...

 

[ban-all-sheds]

Yes, but he's trusting his, his family's and his friends' lives to the fact that the loop resistance is low enough for the protective device to operate properly in the event of a fault....

 

[plugwash]

yeah testing with a multimeter is far better than not testing at all though.

 

[ban-all-sheds]

It will pick up gross errors like open connections, but might lead to a false sense of security.

 

[Adam_151]

On the subjects of ELFI and false senses of security, an interesting read here: http://www.theiet.org/Forums/forum/...=5&threadid=2600&highlight_key=y&keyword1=30% hardly bed time reading, but some interesting ideas.

(sidenote, not seen you post over there for a while ban , though I notice you still post at SF which seems to be getting more *#@^wits delivered by the day, I'm supprised that the serious posters still stick around there... though I have noticed less posts by them in recent weeks)