New Circuit to 17th?

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davetheglitz

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I would like opinions on this one please!

My understanding is that new circuits should be fully compliant with the latest edition of the regs.

If you were to supply a remote outbuilding via an MCB on an existing CU, via an isolator, in 2 core SWA to a TT'd outbuilding with a 30mA RCD board and no additional services, is it necessary to ensure that bonding is up to the latest regs at the CU? My gut and head are fighting over this one! Customer has had several quotes - none have mentioned anyting about bonding.

Hope you can help

Dave

 
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DISAGREE.

I would spec. that main bonds must be present, and correctly sized, before I install a new cct.

New circuit is NOT MWC; therefore you`re doing FULL testing. Missing main bonds is STILL, AFAIK, a code 1 fail. Even if you were to call it a code 2, you are extending an installation which is unsafe by definition.

Dave - I`d push for the bonding. If the customer is a bit dense, and you`re with `em, the NIC do a "free" laminated card explaining the purpose and rules of earthing and bonding.

 
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This is where the issue becomes technical rather than sensible.

I quite agree that it would be preferable to install bonding - however, in what way can the new circuit influence the existing installation, apart from an increased load?

 
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I would like opinions on this one please! My understanding is that new circuits should be fully compliant with the latest edition of the regs.

If you were to supply a remote outbuilding via an MCB on an existing CU, via an isolator, in 2 core SWA to a TT'd outbuilding with a 30mA RCD board and no additional services, is it necessary to ensure that bonding is up to the latest regs at the CU? My gut and head are fighting over this one! Customer has had several quotes - none have mentioned anyting about bonding.

Hope you can help

Dave
I would concur with KME..

if you do want to back up your reasons a bit then....

All alterations should be compliant with the latest regs?

at what point where you able to pick & choose which regs you work too?

You can't say oh! cuz Its only minor... shall I use 14th, 15th, 16th or 17th hmm choices..

And if all work has to be to current regs..then read customer reg..

131.8 Additions & Alterations to and installation (pg 16)

last sentence talks about earthing & bonding being up to scratch!

If don't like 17th.. try 16th..

130-07-01 Additions & Alterations to an installation (pg 14)

oh crap STILL got to check earthing & bonding!!!

Addition/Alteration/Temp OR permanent!

just about covers everything IMHO! :) ;)

 
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Don`t get me wrong - under the circumstances above I would not feel comfortable proceeding with the job unless bonding was installed BUT I can`t see any technical argument for installing the bonding only that the regs require it, without any logical explanation.

 
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ok - how`s this:

IF the installation is in an "unsafe" condition (i.e. no main bonds), and you`ve installed ANY circuit; your new circuit MUST be, by definition, unsafe.

therefore, logically, you have installed an unsafe circuit.

OK?

 
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So no part of an installation can be safe unless the entire installation is safe?An LV fan in the bathroom is not safe because there is a broken socket in the dining room?
Now surly (to an outsider) that's different circuits. The earthing and bonding is common to all?

 
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Not the same thing, is it?

The bonding affects the whole installation. The broken socket affects that circuit.

Even a MWC asks if the bonding is correct.

It is not acceptable to put an X in response, on anything other than a PIR.

n.b. If the LV fan was fed off the circuit the socket was on, and the "broken" (define?) socket affected your readings - then I`d answer "yes"

 
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Now surly (to an outsider) that's different circuits. The earthing and bonding is common to all?
Thanks mate. For even a "non-sparx" to see that (no offence intended), means I`m not COMPLETELY losing my marbles.

I didn`t think everything had to spelt out in precide detail.

Take it the way it`s intended please.

KME

 

davetheglitz

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Just supposing that its a TNCS system with 6mm bonds rather than 10mm. In an inspection this would come in as a code 4 - not to current regs. The inspection would not insist on upgrading. So installing a new circuit that will not be dependant on the bonding? Electrically the risk is next to nothing otherwise the safety council would insist on insufficient bonding as a code 2 - but it's not the current regs! I can see all points of view - but the safest bet could lose you the job on price!

 
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Thanks mate. For even a "non-sparx" to see that (no offence intended), means I`m not COMPLETELY losing my marbles.I didn`t think everything had to spelt out in precide detail.

Take it the way it`s intended please.

KME
I don't get offended easily! Was expecting the 'pushy shovey' response :D

 
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Just supposing that its a TNCS system with 6mm bonds rather than 10mm. In an inspection this would come in as a code 4 - not to current regs. The inspection would not insist on upgrading. So installing a new circuit that will not be dependant on the bonding? Electrically the risk is next to nothing otherwise the safety council would insist on insufficient bonding as a code 2 - but it's not the current regs! I can see all points of view - but the safest bet could lose you the job on price!
It's upto you to explain why extra remedial work needs doing and th extra costs involved. If they want it done cheap there are people out there who cater for the 'cash in hand no cert brigade'.

If extra work needed doing in my house I'd want to know why it wasn't pointed out by another tradesman who'd priced lower.

 
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Apache:

I wasn`t aiming the "no offence" comment at you :(

DTG: as o/p, you have more info on this than we have. However, even if the bonding is sized IAW 15th, AND you could provide good reasons why it does NOT need to be upgraded, AND your readings on the bonding cables are compliant; then leave them alone.

Otherwise upgrade. This SHOULD have been "advised" by everyone, anyway!

We / I have been of the impression that main bonds are missing, or SUBSTANTIALLY undersized.

 
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It's upto you to explain why extra remedial work needs doing and th extra costs involved. If they want it done cheap there are people out there who cater for the 'cash in hand no cert brigade'. If extra work needed doing in my house I'd want to know why it wasn't pointed out by another tradesman who'd priced lower.
Financial considerations are not a valid defence in a court of law, either. Apache, as a non- sparx, is giving you his insight of a "typical" customer.

If they are THAT penny-pinching, do you want to work for `em, anyway?????????

 

davetheglitz

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Now surly (to an outsider) that's different circuits. The earthing and bonding is common to all?
However in this case the earthing is not common as the outbuilding is TT'd, and there are no services - so there are no bonding issues that affect the new circuit. I suppose there is an arguement that if you are holding a water pipe made live by external influence whilst attacking the SWA with a metal handled machette then you might be at risk! Well it could happen to anyone......

 

davetheglitz

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Thanks for the advice! I've already covered the possibility of having to upgrade the bonding on the quote. Just thought it was an interesting little problem!

Dave

 

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