Earthing in a dry line plastic back box

[taylor414]

I wanted to change a single wall socket to a double.

If replacing the patress box with a dry line plastic one do i connect the earth to a connector strip left loose in the box? Because the connector strips come in different rating which one do I use?

Thanks for any help.

 

[Adam_151]

NO!, the cpc should be linked to the earth terminal on the socket outlet, if its not, then you should connect it there!

Additionally there may be a link from the socket outlet to the pattress when the patress is metal, if changing to a plastic patress then remove and discard this link.

Why are you replacing with plastic anyway? if there is a metal one there, then its going to be fixed to something!, which means there should be a noggin there thats in the way of a plastic dryline box, but is in just the right place to screw a metal patress to...

 

[taylor414]

Think ive got mixed up. Being using a DIY book. So you just use a connector strip to earth in a dry line light switch socket. Is that correct?

Can anybody recommend a basic home electrics book?

 

[Adam_151]

You terminate the cpc(s) in a plastic connector block if the accessary doesn't require a cpc (you don't chop it off... it might be needed at a later date!)

A socket outlet will always require a cpc (to connect to the earth pin of the plug), and if the patress is metal then its considered good practice to link the two.

An example of where you might terminate the cpc in a connector block is a plastic switch plate mounted on a plastic pattress


As to the book, I've others recommend the which guide to wiring and lighting, though I've not read it myself (avoid the wiring sections of publications that cover all aspects of DIY... I've yet to find one that doesn't contain glaring errors!)

NB. cpc = circuit protective conductor, the earth conductor that is run with the live circuit (must stop doing that!... afterall I'm first to berate others for sms shorthand, and I'll save myself two letters by doing that )

 

[Lectrician]

Many diyers refer to "light switches" and "light sockets" or "light switch sockets" for some reason!

I think this is what has confused this thread

 

[Softus]

So you just use a connector strip to earth in a dry line light switch socket. Is that correct?

If the light switch has no earth terminal, then there's no nothing to connect the CPC to. In this case you can either sleeve the CPC and bend it over, leaving it unterminated, or terminate it in a connector block.

Can anybody recommend a basic home electrics book?

You could do worse than start with the DIYnot Wiki and FAQ - there are references to recommended reading within.

 

[Softus]

...if the patress is metal then its considered good practice to link the two.

If you have one floating lug then it's optional good practice, but if two floating lugs then it's mandatory good practice.

 

[Adam_151]

Many diyers refer to "light switches" and "light sockets" or "light switch sockets" for some reason!

I think this is what has confused this thread

Could be!, incidentally, strikes me that a 'light socket' or 'lamp socket' is a perfectly logical term for a lamp holder though (but certainly doesn't help when someone applies it to a switchplate! lol)

 

[taylor414]

"In this case you can either sleeve the CPC and bend it over, leaving it unterminated, or terminate it in a connector block. "

Connector blocks come in different rating - which one do you use to earth in this instance or doesn't it matter? Cheers

 

[Adam_151]

...if the patress is metal then its considered good practice to link the two.

If you have one floating lug then it's optional good practice, but if two floating lugs then it's mandatory good practice.

Indeed, I'm guilty of assuming that they all have at least one fixed lug, when probably some don't *slaps wrist*

Also mandantory to fit a link where the earth is provided to the pattress and not the SO (eg, if the wiring system is galv conduit, MI, or SWA)...you can only rely on the lugs to provide an earth to the pattress from the socket outlet, nice vice versa

 

[Adam_151]

Connector blocks come in different rating - which one do you use to earth in this instance or doesn't it matter? Cheers

Use one thats at least rated as high as the fuse/breaker of the circuit the earth is for, eg. on a 6A lighting circuit 10A would be suitable... on a ring final circuit you should use 30A ones

 

[ColJack]

in this instance it matters not one bit which size terminal block you use to terminate the unused earth into..
since not current will flow in it then a 0A block would be fine but they don't make those..

 

[Softus]

It does matter - you should choose the smallest one that the bared conductor will fit into, to reduce the risk of the wire not being clamped tight and thereby slipping out.

 

[Lectrician]

"In this case you can either sleeve the CPC and bend it over, leaving it unterminated, or terminate it in a connector block. "

Connector blocks come in different rating - which one do you use to earth in this instance or doesn't it matter? Cheers

Ohhh - That is bad practice!

 

[Softus]

the thing that I wrote

No he didn't - I did.

Ohhh - That is bad practice!

Please explain why.