More Bonding!

[avinalarf]

Evenin' all!

Just read the bonding thread with interest and it also prompted a question...

Visited a friend's over the weekend who's doing some renovation work. Noticed that an electrician had bonded the towel rail in the bathroom to the cpc in the light switch outside the bathroom.

Can someone confirm that this is ok as I'm unsure.

Thanks, Nat

 

[Apache]

this is supplimentary bonding not main bonding. If your friend is having renovation work done is the CU 17th ed? I thought supp bonding not required if this was the case.

What do you think Nat?

 

[Robojin]

Evenin' all!Just read the bonding thread with interest and it also prompted a question...

Visited a friend's over the weekend who's doing some renovation work. Noticed that an electrician had bonded the towel rail in the bathroom to the cpc in the light switch outside the bathroom.

Can someone confirm that this is ok as I'm unsure.

Thanks, Nat

Is the towel rail an electric type or plumbed?, if plumbed is it in copper or plastic after the rad tails?, is that the only bonding clamp?, is the lighting circuit currently protected by an RCD?

have a look Red Book 544.2 pg135 for the details

 

[Mark2spark]

Yeah, basically Nat there needs to be more info on what type of renovation, or how far are they prepared to go with their renovation, type info given.

But basically it sounds like a typical equi-potential zone.

 

[avinalarf]

Thanks for input so far everyone.

The renovation work isn't that extensive regards the electrics due to lack of funds. Apache, it's defo not a 17th Ed board. I'm going to provide her with an RCD as there isn't one at the moment .

Robo - rad is plumbed in and pipes are copper. It's the only bonding clamp I've seen so far.

Unfortunately, it seems to be a bit of a "hodge-podge" at the moment...her builder is doing the first fix of the electrics and assumed that I'd be hooking up to CU and providing EIC X( Have promptly told her I will do no such thing!

Just came upon this situation with the supp bonding and wondered if it was ok to do it like that??? Have read 544.2.5 and from my interpretation, it seems that what's been done is ok - just need an experienced head to confirm this please.

Cheers

 

[Evans Electric]

I have to say that a load of ( in my opinion) unecessary bonding was spec'd in the 16th ed. Could never see the purpose of a 4mm earth from pipework to the pull switch terminal etc. But then I tend to be a bit bolshie i'm afraid.

Deke

 

[steptoe]

very common misconception with plumbers/builders heating guys this bathroom radiator being bonded rubbish. regs used to make you bond it if continuity to MET was too high, as most of the above NEVER measured E cont they took it as law it ALWAYS had to be bonded, many an argument had about this, even had a building inspector over his head with it, he stood for over 2hours trying to find the reg one day. personally I would RCD the install and rip the sup bonding out, its only going to introduce a potential, esp with so much poly pipe in use these days.

 

[Tarpole]

Just say that any electrical work in a bathroom should be done by a competent person who is registered. Has any bonding been properly tested? There is the possibility of introducing a fault by bonding if you dont test correctly

 

[avinalarf]

very common misconception with plumbers/builders heating guys this bathroom radiator being bonded rubbish. regs used to make you bond it if continuity to MET was too high, as most of the above NEVER measured E cont they took it as law it ALWAYS had to be bonded, many an argument had about this, even had a building inspector over his head with it, he stood for over 2hours trying to find the reg one day. personally I would RCD the install and rip the sup bonding out, its only going to introduce a potential, esp with so much poly pipe in use these days.

So Steps, should I put an RCD to protect all circuits then? This particular job is awkward due to lack of funds by owner, so I'm trying to do as much as possible and make safe without spending OTT.

Being able to get rid of this bonding would be great 'cos it's in conduit on the floor due to the previous spark not being able to get below the floor tiles

 

[avinalarf]

Just say that any electrical work in a bathroom should be done by a competent person who is registered. Has any bonding been properly tested? There is the possibility of introducing a fault by bonding if you dont test correctly

Hi Vensac - I assume the person who did this (some years ago I think) was competent and possibly registered. I shall do some tests when I next visit.

On the subject of introducing a fault by bonding...

My mum showed me some cables under her stairs which were loose. They are 10mm earthing cables . Really not sure where they're coming from as they're under the floor which is tiled! Did a couple of tests from these to the main earth cable and the readings were over 2.??ohms

The gas pipe had an earth clamp with cable coming from it, but wasn't connected. Did tests before and after connecting it to the MET, but the readings were the same. Don't suppose someone could tell me why this would be the case? I'm rather concerned, but must admit that the last time a spark was in my mum's house was over 5 years ago, so it's been like this all that time

 

[green-hornet]

Regarding equipotential bonding, there is no requirment under the 17th edition, however the Electrical Safety Council will ask you to test across hot and cold to establish a reading <0.05 ohms.

Main bonding has to be in place and a requirment in testing is to verify connection, this is normally done with a wander lead nulled and a reading of 2000 etc would mean no connection, I have found 10mm from the Gas to 4mm under floor so you have to check, builders will do anything!!.

You will have to trace the cable or fit new cables.

Just a footnote I did a small job on a house that was fully rewired 10 years ago, the electrician never bothered to re connect the main 16mm earth!!

So never take anything for granted.