CPC/Earth feed to Light Switch Back Box

[BettyBoop44]

Hi
Just a bit of info required , just been checking all over the house checking for a earth feed to light fittings and switches , ( a friend informed yesterday that there friend have more or less sold there house , but an electrcal inspection has come up with no cpc to all the light switches ) .
I have found 3 light switch back boxes that do not have a earth feed to them , now the question is can I fit a plastic box inplace of the metal one that is in there and not need a earth feed to them ! .
All the light fittings have a earth feed to them ! , every circuit in the house is protected by a RCD .
cheers
BB

 

[BettyBoop44]

it's also an earthing terminal (MET). better would be to connect to the earth bar in the CU in the correct point for the circuit. and, if not mechanically protected, should be min. 4mm, but that's a minor point.

Hi
Thanks for your reply , what would be classed has "mechanically protected" under the floor boards ! , that is were I put the 2.5mm² cpc run , crikey I would not of liked to have tried to put 4mm² to my light fittings , the ceiling would of come down with the weight of the copper lol .
anyway thanks for your reply , great place to learn .
ps: by the way when did that reg come out 543.1.1 regarding the 4mm² , will feed it into my CU , has been recomemended , where I have it fed from now is the same point my CU is fed from ! .

BB

 

[westward10]

I have just found the same Reg 543.1 in my 1981 Fifteenth Edition but it has been around longer than that.

 

[Pete999]

Hi
Thanks for your reply , what would be classed has "mechanically protected" under the floor boards ! , that is were I put the 2.5mm² cpc run , crikey I would not of liked to have tried to put 4mm² to my light fittings , the ceiling would of come down with the weight of the copper lol .
anyway thanks for your reply , great place to learn .
ps: by the way when did that reg come out 543.1.1 regarding the 4mm² , will feed it into my CU , has been recomemended , where I have it fed from now is the same point my CU is fed from ! .

BB

2.5 protected i,e, in conduit or trunking, yes the MET is electrically connected to the earth bar in your CU but it is recommended that cpcs are connected in the CU

 

[BettyBoop44]

2.5 protected i,e, in conduit or trunking, yes the MET is electrically connected to the earth bar in your CU but it is recommended that cpcs are connected in the CU

Hi
Thanks again for your help , just one more and I will leave you alone , if I was to get a EICR for my house would they not pass it , if they had seen the 2.5mm2 cpc I put in the ceiling void to the lights ! .

 

[westward10]

Hi
Thanks again for your help , just one more and I will leave you alone , if I was to get a EICR for my house would they not pass it , if they had seen the 2.5mm2 cpc I put in the ceiling void to the lights ! .

Depends how clued up the person is doing the inspection.

 

[BettyBoop44]

2.5 protected i,e, in conduit or trunking, yes the MET is electrically connected to the earth bar in your CU but it is recommended that cpcs are connected in the CU

Hi
Thanks again for your help , just one more and I will leave you alone , if I was to get a

What size cpc and what routing did you take when installing he seperate cpc as there are regulations governing what should be done

Hi
From the MET straight up into the loft then through each floor joist to each light ! , going to put it into the CU earth bar instaed of the MET .

cheers

 

[Pete999]

http://www.----------------------------/mediafile/100404922/Best-Practice-Guide-4-Issue-4.pdf
Give it a C3 possibly C2 is about all I could recommend from a distance

 

[BettyBoop44]

I have just found the same Reg 543.1 in my 1981 Fifteenth Edition but it has been around longer than that.

Thanks for that , looks like I am going to have to change the 2.5mm2 to 4.0mm2 to the lights mam a mia , that was a job and a half putting in the 2.5mm2 from what I can remember , but you can't have enough supplimentry bonding in the house and I have a lot , water n gas pipes were I have been able to get to them , I hink there is more copper in the cpc's around the house than in Zambia ! .

cheers guys and thank you all for your comments and help .

BB

 

[Pete999]

Thanks for that , looks like I am going to have to change the 2.5mm2 to 4.0mm2 to the lights mam a mia , that was a job and a half putting in the 2.5mm2 from what I can remember , but you can't have enough supplimentry bonding in the house and I have a lot , water n gas pipes were I have been able to get to them , I hink there is more copper in the cpc's around the house than in Zambia ! .

cheers guys and thank you all for your comments and help .

BB

If you are going to access the routes to the lighting points why not run a new twin and cpc cable? sounds like you have been bunging supplementary bonding every where, has the pipework been tested to see if it actually requires bonding?

 

[telectrix]

i'd give the 2.5mm cpc a C3,

 

[davesparks]

Thanks for that , looks like I am going to have to change the 2.5mm2 to 4.0mm2 to the lights mam a mia , that was a job and a half putting in the 2.5mm2 from what I can remember , but you can't have enough supplimentry bonding in the house and I have a lot , water n gas pipes were I have been able to get to them , I hink there is more copper in the cpc's around the house than in Zambia ! .

cheers guys and thank you all for your comments and help .

BB

Was all that bonding actually necessary? Bonding things which don't need it can potentially increase danger rather than reduce it.
It would be far better to rewire the circuit than run an additional cpc, the old cables are likely to be getting towards the end of their expected lifespan of they aren't past it already.

What Zs readings did you get when you tested the 2.5mm cpc?

 

[BettyBoop44]

Hi
Thanks for your reply, yes you are right am going to rewire all the lower floor lights and switches , to be honest I was thinking of doing just that , just needed someone to push me to do it .
Best regards
BB

 

[BettyBoop44]

Thanks for all your feedback again have decided to rewire the lower lights n switches , my next question is what is the recomended csa of the cable to use ! .
ie 1.omm2/1.5mm2 / 1.5mm2 for radial n 1.00mm2 to switches ! .
cheers

BB

 

[davesparks]

Thanks for all your feedback again have decided to rewire the lower lights n switches , my next question is what is the recomended csa of the cable to use ! .
ie 1.omm2/1.5mm2 / 1.5mm2 for radial n 1.00mm2 to switches ! .
cheers

BB

The recommended size is the size which you have calculated using the information in your regulations book.
Mixing cable sizes in a simple installation is unnecessary, calculate thencable size required for the circuit and stick to that size throughout the circuit.

 

[BettyBoop44]

Was all that bonding actually necessary? Bonding things which don't need it can potentially increase danger rather than reduce it.
It would be far better to rewire the circuit than run an additional cpc, the old cables are likely to be getting towards the end of their expected lifespan of they aren't past it already.

What Zs readings did you get when you tested the 2.5mm cpc?

Hi
Thanks for your reply , is there a need to check the Zs when there is a RCD in the circuit ! .
BB