Earth Bonding and Surveyor Rant

Kalifornia777 · 25 Mar 2019

my house was build in the 70s/80s, the wiring and consumer unit are the original. I am planning on moving house so undertook a electrical safety check. the main findings were that gas and water pipe need to be bonded. the current bonding is apparently 6 mm - new regs mean it should be 10mm so I am told.

1) The electrician has suggested he runs a cable from the consumer unit through the ceiling to the gas mains and under the sink in the kitchen. This is not ideal as this will cause a lot of mess and not something I need right now as we want to move. The estimate is 600+VAT, which seems excessive considering its a small 2 bed property.

2) I did notice the the previous earthing involved a metal tag around the pipe with the earth wire buried into the wall, does this method not suffice anymore.

3) The main water inlet (stop cock just outside the front door) is made of plastic.

4) A surveyor did a homebuyers report where he claims the installation does not have a modern cut of device. He claims this is a clear fire hazard. And is insisting we install a new consumer unit with MCB and RCD.

Any advice would be appreciated.

JohnD · 25 Mar 2019

Kalifornia777 said:
4) A surveyor did a homebuyers report where he claims the installation does not have a modern cut of device. He claims this is a clear fire hazard. And is insisting we install a new consumer unit with MCB and RCD.

it is most unlikely that he has any electrical qualification. You might like to ask him.

He can't insist you do anything. Potential buyers are entitled to form an opinion on the desirability and value of the house as it stands, or on what it might be if you made some changes. The amount they are willing to offer may vary. The variance might not be the same as the cost of the work the surveyor suggests.

Your installation looks like it might be about 40 or 50 years old and a potential buyer may well decide to carry out extensive rewiring and modernisation, for example adding more sockets and modern switches and outlets according to his taste and preferences. Any work you do may differ from them. This buyer is also likely to carry out redecoration and other works, which are often more convenient to schedule after renovations.

If you are thinking of renting the house out, rather than selling it, it needs looking at with a different eye.

Kalifornia777 · 25 Mar 2019

JohnD said:
it is most unlikely that he has any electrical qualification. You might like to ask him.

He can't insist you do anything. Potential buyers are entitled to form an opinion on the desirability and value of the house as it stands, or on what it might be if you made some changes.

Your installation looks like it might be about 40 years old and a potential buyer may well decide to carry out extensive rewiring and modernisation, for example adding more sockets and modern switches and outlets according to his taste and preferences. Any work you do may differ from them.

The electrician marked earth bonding to gas and water as a C2 on the electrical safety cert. but then quoted me 600+Vat to have the work done.

JohnD · 25 Mar 2019

The bonding would conform no less it if was done with surface wiring, for example tacked to the skirting or picture rail. This would be much cheaper but less elegant. lifting floors is quite a lot of work.

Kalifornia777 · 25 Mar 2019

JohnD said:
The bonding would conform no less it if was done with surface wiring, for example tacked to the skirting or picture rail. This would be much cheaper but less elegant. lifting floors is quite a lot of work.

this is what is effectively there at the moment, I guess I could DIY it and replace the wire for a 10mm to no longer a C2 Issue.

securespark · 25 Mar 2019

I would mark it as C3 with a comment.
How can you code it C2 without doing an Adiabatic?

EFLImpudence · 25 Mar 2019

What are the positions of the gas and water supplies? Are they near each other?

You could achieve the desired compliance by running a 10mm² conductor (green and yellow wire) between the two and connecting to the existing bonding conductors and pipes.

Kalifornia777 · 25 Mar 2019

securespark said:
I would mark it as C3 with a comment.
How can you code it C2 without doing an Adiabatic?

So even with a 6mm earth surface bonding you would classify it as a C3 rather than a C2?

Sorry I don't know what a Adiabatic is?

Kalifornia777 · 25 Mar 2019

EFLImpudence said:
What are the positions of the gas and water supplies? Are they near each other?

You could achieve the desired compliance by running a 10mm² conductor (green and yellow wire) between the two and connecting to the existing bonding conductors and pipes.

One is under the stairs, the other is about 12 ft away in the kitchen - no easy way of getting wire without surface mounting or drilling through walls.

Kalifornia777 · 25 Mar 2019

securespark said:
I would mark it as C3 with a comment.
How can you code it C2 without doing an Adiabatic?

Is there anyway of getting the electrician to downgrade the original assessment from C2 to C3?

JohnW2 · 25 Mar 2019

You haven't yet clarified whether you are wanting to sell the house or rent it out - since, as has been said and implied, the advice we would give you would probably be very different in those two situations.

Kind Regards, John

Kalifornia777 · 26 Mar 2019

JohnW2 said:
You haven't yet clarified whether you are wanting to sell the house or rent it out - since, as has been said and implied, the advice we would give you would probably be very different in those two situations.

Kind Regards, John

Im selling the house, they buyers are FTB

securespark · 26 Mar 2019

C2 means potentially dangerous.
The Adiabatic is a calculation you can make to see if a smaller (than the standard size conductor listed in the regs) bonding conductor will suffice.
My point was that an assessor cannot say a certain conductor size is potentially dangerous unless he has done the calculation to prove it.

Kalifornia777 · 26 Mar 2019

securespark said:
C2 means potentially dangerous.
The Adiabatic is a calculation you can make to see if a smaller (than the standard size conductor listed in the regs) bonding conductor will suffice.
My point was that an assessor cannot say a certain conductor size is potentially dangerous unless he has done the calculation to prove it.

I guess I can ask him to prove he did the calculations - is there a way I could work this out?

EFLImpudence · 26 Mar 2019

The 'adiabatic' calculations don't directly apply to bonding conductors in this situation.

A minimum 10mm² is required nowadays.

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