Main protective bonding

[Luminous]

Just changing a CCU and the existing bonding to the services is in 6mm. I can get to the gas incoming very easily to change to 10mm but there is no way I can get to the water incoming service (middle terrace, stone floors, just decorated) without a load of trunking or up and over the house. Even if I did the service is now behind the kitchen units with just a small hole for the stop tap.
However, there is a radiator pipe below the CCU. Can I bond to that? Looked throughout the regs and can just find 'as near as practicable to point of entry'. This seems to be the nearest most practicable point but it's obviously from the 'wrong' side of the boiler.

Any advice?

Thanks

 

[Animal]

can you check the continuity of the bond to the water with a wander lead. ? if it's intact, then you could leave as is and note on your EIC.

 

[Octopus]

Given the water bonding is 6mm have you done a continuity test on it? You may be surprised by the results.

If the reading is 0.05 ohms or less a read of BS 7671 131.8 may help you!

 

[Animal]

you have not mentioned the type of earthing . what earthing arrangement do you have.?

 

[DurhamSparky]

if TT its fine..!!

 

[Luminous]

Excellent

'Furthermore, the earthing and bonding arrangements, if necessary for the protective device measure applied for the safety of the addition or alteration, shall be adequate'

Yes, the reading was pretty much 0.01.
That saves me a lot of hassle.

Thanks guys.

edit/ sorry, it's TN-S

 

[DurhamSparky]

just note the cert as to increase bonding at next opportunity!

 

[Octopus]

Excellent

'Furthermore, the earthing and bonding arrangements, if necessary for the protective device measure applied for the safety of the addition or alteration, shall be adequate'

Yes, the reading was pretty much 0.01.
That saves me a lot of hassle.

Thanks guys.

edit/ sorry, it's TN-S

Too many people rush to change bonding when the rules allow for existing installations to remain as is. So make sure you refer to the appropriate reg number on the EIC.

 

[truckster]

Not looking for an arguement but how does 131.8 say that its ok to leave as is? As I read it it says you can't make additions or alterations unless the existing is adequate. I had a discussion with my assessor and he said that 6mm bonds were ok if they showed no signs of deterioration but the PME regs require 10mm. Where do you get the 0.05ohms figure from?

 

[malcolmsanford]

The 0.05 figure is really just a guide line as you would not expect a bonding cable to be over that, but it is just a guide.

As you say your quite right PME bonding must be sized according to table 54.8 and that is indeed 10mm. Bottom line is if the existing 6mm bonding, and it is PME, does not show signs of damage then as a risk assement should can done, I think most of us would keep the bonding, though as it would be the OP signature on the EIC, it would be them held responsible if anything happened.

 

[truckster]

And the debate will rumble on, cheers dude!

 

[Elidor]

I dont think BS7671 states a distance but the building regs do. Im looking at the elctricians guide to the building rgulations and on section 3.3.2 (page 39) it says "...iii The connection to the gas, water, oil, etc. service should be within 600mm of the service meter, or at the point of entry to the building if the service meter is external, and must be on the consumer's side before any branch pipework and after any insulation section in the service. The connection must be made to hard pipe, not to soft or flexible meter connections"

 

[Elidor]

No idea where you stand on existing / old installations. But i was under the impression that part of the initial verification process would be to ensure the addition or alteration to the existing installation is safe. If the calculations are all good with the 6mm can it be left? or would this part of the installation have to be upgraded to 17th edition spec?

/edit Check this link out, looks positive for you on point 5. But not so on point 6, im evern more confused lol

http://www.voltimum.co.uk/news/8851/cm/17th-edition-awareness.html

 

[truckster]

Back again Electrical Safety Council :-
"
Q5. Can I carry out an alteration or addition to an existing installation that has inadequate earthing and/or bonding arrangements?


No. Any alteration or addition to an existing installation must comply with the current edition of BS 7671 (including any amendments). This requires any earthing and bonding arrangements upon which the alteration or addition relies for safety to be adequate. Any exposed-conductive-parts of the new work must not be simultaneously accessible with exposed-conductive-parts of the existing installation that are not connected to the same earthing system.
Regulation number(s)

• 131.8
• 633.2
• 411.3.1.1"

Then this:
Q12. When carrying out electrical work on an installation forming part of a TN-C-S system, is it necessary to upgrade existing 6 mm² protective equipotential bonding to 10 mm²?


Not necessarily. If the existing 6 mm² bonding connects all the extraneous-conductive-parts to the main earthing terminal, has been in place for a significant time and shows no signs of thermal damage, then it may not require to be upgraded.
Regulation number(s)

• 131.8
• 544.1.1

Make your freaking minds up!!!

 

[Goody]

The 0.05 figure is really just a guide line as you would not expect a bonding cable to be over that, but it is just a guide.

As you say your quite right PME bonding must be sized according to table 54.8 and that is indeed 10mm. Bottom line is if the existing 6mm bonding, and it is PME, does not show signs of damage then as a risk assement should can done, I think most of us would keep the bonding, though as it would be the OP signature on the EIC, it would be them held responsible if anything happened.

If the figure 0.05 ohms is just a gude, what is the tolerance... how high a value is acceptable?

Thanks!