Bonding

[carl9254]

Just been to view a property that wants a straight forward c/u change, gas is bonded as its next to the c/u, water is not.

Do i have to bond it or can i put it on the cert as a recommendation?? The main water tap is at the other side of the property and would involve taking out kitchen cupboards, taking up wood flooring etc, making the job bigger than the customer wants.

I think the answer is yes it has to be bonded but what are your thoughts??

Thanks.

 

[yellowvanman]

You've already answered your question. But remember the clause 'as near as practicable'.

Can you use other copper water pipes as an earth conductor? ie. bond to the hot if its near the CU and then cross bond from the hot to the cold under the sink - only works though if the hot is all copper (no plastic inserts).

 

[Guest123]

Reg 131.8.

 

[yellowvanman]

The other thing to try is test the water pipe as to whether its extraneous or not!

Insulation test between main earth and stop cock - if less than 25K then its got to be bonded, if greater then don't need to bond!

 

[morph]

The other thing to try is test the water pipe as to whether its extraneous or not!

Insulation test between main earth and stop cock - if less than 25K then its got to be bonded, if greater then don't need to bond!

dont it have to be more than 2 M ohm ? cant think why i use that figure though to be honest

 

[yellowvanman]

Its actually got to be less that 22K, but I round it up to 25K

Based on the resistance of a person being 1K, if they touch a live part path and extraneous part resistance would be 22K + 1K

10mA current is 'safe', 230V/23000 = 10mA

Anything above 25K would result in current <10mA

 

[morph]

oh ok makes sense now
i was thinking of
do i need supplementary ie where if you have blah blah and the resistance is less than 1667 or more than 2 M ohm then you dont need it ( something like that )

Its actually got to be less that 22K, but I round it up to 25K

Based on the resistance of a person being 1K, if they touch a live part path and extraneous part resistance would be 22K + 1K

10mA current is 'safe', 230V/23000 = 10mA

Anything above 25K would result in current <10mA

 

[Spudnik]

If the pipework installation is copper throughout then it should still be bonded, even if the supply to the property is PVC.

I ALWAYS upgrade main bonds when changing a CU.

Never had resistance from the customer yet.

 

[i=p/u]

why would they complain if its the lifesaver in electrical but what would you do if floors and cupboards wernt to be touched, could you run it along the soffit or eves of houses?? or would you go about it??

 

[ian]

I come across this all the time, I usually point out thereasons behind bonding, and show them the NIC guide. That usually does thetrick.

 

[Spudnik]

why would they complain if its the lifesaver in electrical but what would you do if floors and cupboards wernt to be touched, could you run it along the soffit or eves of houses?? or would you go about it??

As Ian said really.

Once explained, then you can talk through with the customer costs and best route to take.

In some cases, they are happy with either black or white conduit at low level outside.