bonding question

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soulman

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whether doing minor or major work, i know the bonding should be checked and if it is non existent it should be installed before any work commences, what if the installation has bonding of 6mm and there is no sign of deteriation, continuity checks out o.k. and the work is fairly minor, say installation of a new circuit. would it be required to upgrade the bonding? If the work was major i would upgrade the bonding anyway. i would be inclined to leave 6mm for tt, have read the regs and not clear about tn-c-s or tn-s. Any help appreciated.

Cheers

 
I'd say there ok then cos main earth has to be 10mm and water gas can be 6. Unless your upgrading tails I'd leave it

 
no if i was upgrading tails for example consumer unit change the bonding would be upgraded to current standards anyway. Was just wanting to query what you guys do when faced with smaller bonding conductors on little jobs. As i dont want to upgrade bonding when it not considered neccessary resulting in more expense & disruption for the customer.

Cheers

I was taught the earthing conductor should not be less than half the size of the tails & the main bonding conductors should not be less than half the earthing conductor cannot find this in the bgb probably looking in the wrong place.

 
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I've no books at hand and that's just of top of my head not sure if it's changed though

 
I've been lead to believe that when filling in a test sheet when it say adequate earthing that would mean on a domestic tns - tncs system the earthing must be 10mm and when you go to start work, the bonding is anything under that, it is inadequate.

As for the mains if you are adding another circuit and your diversity exceeds 87 amps the 16 tails are no longer big enough based on a 100 a main fuse, therefore needing 25 mm tails then requiring a 16 mm earth so one circuit opens a can of worms

 
Most domestics I've come across the main cut out is either 60 or 80 amp fuse but just because the sticker on the cartridge normally says bs 1361 type 2 100 amp I bet most people note that down. I tend to put 25 mm tails in wot ever the fuse size just in case it ever gets changed for a higher rating

 
Depending on the characteristics' of the incomer, if it

 
The Adiabatic equation does not apply to bonding.

By current regs you are allowed to have one unbroken run of 10mm to bond both gas and water. In an electrical sense I don't see the difference between that and having a 6mm to water, 6mm to gas and all cross bonded by a big metal manifold at a gas boiler. To my mind it's then a 'bonding ring' so will take a hefty current.

 
Yesterday, I was having a drink with one of the neighbours. He was changing stuff in the garage including moving a light fitting which he asked me about when he saw me washing the car. I noticed no MEB to his gas meter and he said "yeah thats right, wasnt it never required years ago?"

Anyway he had a new bathroom and electric shower fitted a couple of years ago by a local company, so they probably didnt notice or bother to check that the water wasnt bonded as well (or perhaps the problem is that the stopcock is under the floor boards in the utility room), the earthing conductor is a 6mm black neutral and not an rcd insight.

Mind you I was only there enjoying a cup of tea and the sunshine :)

 
I think it's impractical to expect the customer to pay for an upgrade of the MEBC when you may be doing a notifiable job that is small in comparison. Obviously if the testing and inspecting shows that an upgrade has to be done, you and the customer really may have no choice.

 
...this person needs some advice as well. Looks like an RCD weatherproof socket on one side and then a surface plastic switch on a 16mm patress wired in mini trunk on an outside wall; a bit hard to tell from the picture. I can see it all ending with red faces and tears all around.

ebay item number 260982485272

:coat

 
I know the seller of that. It's around the back garden and they use it when it rains , you can actually put your finger in the bottom of the patress and get a fantastic jolt which is very sexy. Got to try it to believe it. Might Bid for it.

 
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