Bonding... can I keep it at 6mm?

[crotley32]

Hi guys any advice.
I have had a request for a consumer unit change. I always carry out a condition report prior to find any issues that need resolving. The installation has a few defects but no C1's . It's a TNS installation and the main earth is 10mm and bonding to gas and water both 6mm the gas is easy to upgrade to a 10mm but the water is another matter it's virtually impossible to get a new cable to the water stop tap without causing disruption to the internal fabric. The client wants no damage! And I don't have my magic wand.
So my question is it ok to leave the 6mm to the water, continuity has been confirmed and make a note on the installstion cert?
Thanks

 

[Midwest]

Back to my chilli, urrrgh I mean me Pigeon

 

[westward10]

I wonder how one defines "adequate".

 

[Ian1981]

Aha The Best Practice Guide, it is a fool who relies upon this as opposed to BS7671.

I'll grab my jesters hat then shall I!?

What a good persuasive answer that was!

 

[Ian1981]

I wonder how one defines "adequate".

Sufficient, acceptable, enough, ample

 

[westward10]

Wasn't having a dig at you Ian though I see it looks like it now, it was a generalisation. I always think oh God here we go The Best Practice Guide, even the title irritates me.
Me if I replace a consumer unit I will upgrade the earthing conductor and bonds because I don't like this adequate scenario because there are no parameters to judge this by.

 

[Ian1981]

Wasn't having a dig at you Ian though I see it looks like it now, it was a generalisation. I always think oh God here we go The Best Practice Guide, even the title irritates me.
Me if I replace a consumer unit I will upgrade the earthing conductor and bonds because I don't like this adequate scenario because there are no parameters to judge this by.

No I agree that I would upgrade earthing conductor and protective conductors if possible as it would improve the installation to current standards.
Just I think if you can't possibly upgrade the water in this case there is an argument that it can be left as it is.
The problem with text is that you really can't tell the manner in which it's written.
No problem Westwood I like your honesty as it's to the point.

 

[joelee131]

According to the yellow book chapter 54, 543.1.1, 4mm2 is minimum with no mechanical protection, so 6mm is fine for bonding conductor.

 

[Ian1981]

According to the yellow book chapter 54, 543.1.1, 4mm2 is minimum with no mechanical protection, so 6mm is fine for bonding conductor.

That's supplementary equipotential bonding not main protective bonding conductors

 

[joelee131]

Still a bonding conductor. 6mm2 is fine.

 

[joelee131]

Make sure you check the termination to the ID plate is correct and secure.

 

[Ian1981]

Still a bonding conductor. 6mm2 is fine.

Read regulation 544.1.1
544.1.1 Except where PME conditions apply, a main protective bonding conductor shall have a cross-sectional area not less than half the cross-sectional area required for the earthing conductor of the installation and not less than 6 mm². The cross sectional area need not exceed 25 mm² if the bonding conductor is of copper or a cross-sectional area affording equivalent conductance in other metals

 

[joelee131]

544.1.1 refers to earthing conductor, the bonding to water or gas pipes is a way of reducing the risk of electric shock, that's why they are called bonding to achieve the equipotential for the whole installation wherever possible.

 

[Ian1981]

4mm would be for supplementary bonding between say hot and cold pipes in a bathroom where 4mm can be used without mechanical protection.
If mechanically protected throughout you can go as low as 2.5mm2

 

[Ian1981]

544.1.1 refers to earthing conductor, the bonding to water or gas pipes is a way of reducing the risk of electric shock, that's why they are called bonding to achieve the equipotential for the whole installation wherever possible.

No it referes to a main protective bonding conductor
Not the earthing conductor
2 different things explained in the definitions

 

[Ian1981]

No it referes to a main protective bonding conductor
Not the earthing conductor
2 different things explained in the definitions of bs 7671