Earthing

keniff · Mar 23, 2011

Where do you stand with adding circuits to a installation that has the bonding undersized? It's in 6mm and should be 10mm to be up to regs but customer doesn't want it replaced? Can I do the work and advise this should be replaced it's tnc-s

mkoffulham · Jun 22, 2011

so the 4mm in the 10mm tande should be ok. what about the push button breakers are they still allowed or do they have to be changed to 60898 breakers

tony mc · Jun 22, 2011

Malcolm has already answered the question a little earlier in the post.

Depending on the ref method I would't be happy with 10mm twin and earth as tails but you have to do your calcs and justify your report. As IQ has mentioned in the past these are questions while studying for the 2391 not while performing a PIR and I have to agree fully with him.

I hope this has answered your questions.

HI i need a few questions answered as i am new to the game and starting off on my own!!
I went to do a pir today and the main cables from the isolator to consumer unit was it 10mm twin and earth. the earth is only 4mm on this. is this ok??
Though not ideal the 10mm tails maybe sufficient. As the Earthing conductor is greater than 2.5mm on a TN-S system then if you prove it by adiabatic equation then it can be ok. Is it mechancially protected as states in Reg 543.1.1, if not you code it a 2

I could not find the main water incoming to the property but i have seen cross bonding under kitchen sink which runs back to cu in 6mm, is this adequete??
Can you prove that the 6mm cross bonding under the sink goes back to the MET ? Have you done a continuity Test on it? If you can not confirm the prescence of bonding then a code 2

Its a TNS system with the main incoming in pyro and using the sheath as the earth.
also are the push type circuit breaker still allowed or do they have to be changed to 60898 trip switches?
These could already be BS 60898 MCBs it depends on their age. The majority of these are the old BS 3781. Providing that your Zs values are acceptable for the protection device fitted and there is no sign of heat or mechanical damge, then no code

the landlord needs a passed certificate so needs any works done. cheers for the advise!!

oldAL · Jun 23, 2011

tony mc said:
Malcolm has already answered the question a little earlier in the post.

Depending on the ref method I would't be happy with 10mm twin and earth as tails but you have to do your calcs and justify your report. As IQ has mentioned in the past these are questions while studying for the 2391 not while performing a PIR and I have to agree fully with him.

I hope this has answered your questions.

HI i need a few questions answered as i am new to the game and starting off on my own!!
I went to do a pir today and the main cables from the isolator to consumer unit was it 10mm twin and earth. the earth is only 4mm on this. is this ok??
Though not ideal the 10mm tails maybe sufficient. As the Earthing conductor is greater than 2.5mm on a TN-S system then if you prove it by adiabatic equation then it can be ok. Is it mechancially protected as states in Reg 543.1.1, if not you code it a 2

I could not find the main water incoming to the property but i have seen cross bonding under kitchen sink which runs back to cu in 6mm, is this adequete??
Can you prove that the 6mm cross bonding under the sink goes back to the MET ? Have you done a continuity Test on it? If you can not confirm the prescence of bonding then a code 2 or a code 4

Its a TNS system with the main incoming in pyro and using the sheath as the earth.
also are the push type circuit breaker still allowed or do they have to be changed to 60898 trip switches?
These could already be BS 60898 MCBs it depends on their age. The majority of these are the old BS 3781. Providing that your Zs values are acceptable for the protection device fitted and there is no sign of heat or mechanical damge, then no code

the landlord needs a passed certificate so needs any works done. cheers for the advise!!