Board Change questions

[energizedelec]

ok so iv been working as an electrician for 3 years so still have a lot to learn. Im doing a board change for a friend iv bonded the gas and water as there was no bonding in place originally, also tested all of the circuits found a couple of things like shared neutral on the lighting circuit which iv now sorted out, all of the test results were compliant. i was wondering if i need to add earth cables to the metal back boxes of switches and sockets? also as the bonding is in place do i need to add any supplementary bonding on taps etc. when is supplementary bonding needed?

thanks a lot chris

 

[Spazz]

all back boxes need to-be earthed - just run a cable from the socket to the back box. ITs a steal structure and that needs to be bonded as well under BS7671.
You dont need to bond anything after the water supply pipe.
If you have plastic pipes in-between the sink and the supply you can if you think there is a risk of the sink coming live in fault conditions - Im sure you can work this out.

 

[telectrix]

i was wondering if i need to add earth cables to the metal back boxes of switches and sockets?

not necessary if box has at least 1 fixed lug. a fly lead from box to a faceplate is required if the cables are in metallic conduit, with the conduit used as cpc.

 

[trev]

:iagree: with The Tel

 

[Rockingit]

Agreed, although I always still put a fly lead in just out of habit!

 

[trev]

Agreed, although I always still put a fly lead in just out of habit!

Me too mate, old habits die hard

 

[Geoffsd]

also as the bonding is in place do i need to add any supplementary bonding on taps etc. when is supplementary bonding needed?

Supplementary bonding is required to ensure there is no potential difference between simultaneously accessible parts under fault conditions.

It is not there to make circuit protective device operate.


With RCD protection it is very unlikely supplementary bonding will be required in the bathroom, let alone any where else.

Isolated sinks, metal baths etc. should not be bonded and should never be earthed.

 

[oldtimer]

:iagree: with The Tel

Me to as a 14th edition spark then yes if counduit is the main source of earth but T&E no because I used to do it as I was told to but I have found the T&E cpc going to the stud first and then the socket to be broken

 

[Richard Burns]

ok so iv been working as an electrician for 3 years so still have a lot to learn.
Im doing a board change (assume the board is compliant with the current regulations with RCD protection where required) for a friend iv bonded the gas and water as there was no bonding in place originally (assume the bonding is of the correct CSA and connected in the correct locations), also tested all of the circuits found a couple of things like shared neutral on the lighting circuit which iv now sorted out, all of the test results were compliant(therefore the installtion is suitably protected by ADS). i was wondering if i need to add earth cables to the metal back boxes of switches and sockets? also as the bonding is in place do i need to add any supplementary bonding on taps etc. when is supplementary bonding needed?

thanks a lot chris

See my notes in red above if all these conditions are in place then there is no requirement for supplementary bonding (i.e. there is ADS, correct bonding to all incoming services/metalwork and there are 30mA RCDS protecting the circuits where required). So from what you have said you would not need supplementary bonding. If these were not in place then as Geoff said: Supplementary bonding is required to ensure there is no potential difference between simultaneously accessible conductive parts under fault conditions. Then there is a lot more checking and testing required.

Agree with Tel on the backboxes so long as the back boxes do not have plastic lugs, i.e. if there is an earth path created by the connection of the faceplate crew to the back box they will be earthed, however if you feel you can put the fly leads in then this would also be a good thing, but not required.