Earthing

[keniff]

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

 

[keniff]

If you look at table 54.7 page 130 of brb that might help you, in your case I think it should be a 10mm protective conductor but then it's existing and I wouldn't know what/if you would code that as also if pme I understand the water and gas bond should be 10mm but again on a pir u would use the adiabatic as I understand but as the others have stated u need to be confident to do pir's

 

[mkoffulham]

Hi i have done a few so far and most have been satisfactory so the odd non compliance here and there you dont see everyday is sometimes tricky to comment on. This system has been in working order and had no problems no signs of burns on earths and main 10mm not overheating . It would cause alot of damage to the persons house to change main cable and main bonding to current standards as is ran from downstairs to 1st floor.Your advise is appreciated

 

[mkoffulham]

Also the maximum demand of the property is around 45-50 amps

 

[malcolmsanford]

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!!

Your PIR is a report on the installation as it stands and is your responsibility to assess wether it is still safe for continue use as it was designed for.

There is not an installation pre 2008 that will be current to the regulations so therefore you can not give an unsatifactory report unless there are clear indications that it either "Requires urgent attention" or "Requires Improvement". You alone as the tester must ascertain the installations condition, and as IQ as already pointed out you need experience, a thorough working knowledge of the BS 7671-2008 and perhaps in your situation guidance from a more experienced electrician.

 

[mkoffulham]

could someone help me with the adibiatic equation the Ze was mesured at 0.20 ohms pscc was 1.2ka main fuse was 1361 type 2 60amp tns system. all is copper thanks guys.

 

[tony mc]

Some good advice.

mkoffulham I would just report all my findings on the PIR and in a covering letter regardless how much work needs to be done.

I am not saying this is the case in your instance but landlords only want a PIR report with Satisfactoty on it so they can continue getting income via the rent IMO.

Remember its your signature on that report and its you alone who will have to answer any questions if a problem does come up in the future.

 

[tony mc]

230/0.20 = 1150A

1150 x 1150 x 0.1 = 13225 square root = 363.66 / k (115) =3.1 min csa 4mm

 

[IQ Electrical]

Just ignore this!

 

[tony mc]

IQ I thought he said it was a TNS earthing .

 

[IQ Electrical]

IQ I thought he said it was a TNS earthing .

And right you are, my apologies, where's my coat?

 

[mkoffulham]

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]

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]

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!!

not much to add, but it simply a non compliance so I wrote in blue

 

[IQ Electrical]

not much to add, but it simply a non compliance so I wrote in blue

Absence of main protective bonding is a code 2.