Supplementary Bonding or RCD Protection

[marnerbird]

Hi All,

I am half way through a partial rewire (registered with LABC) and am just about to start on installing the supplementary bonding in my bathroom (non existant at present). Before I start, I seem to remember being told that if all electrical items in the bathroom (towel rail, shower, 2 lights) where RCD protected there would be no need to do supplementary bonding. Is this correct ?

The re-wire is being done to the 16th edition, which is why I've asked as not all circuits will be covered by RCD's and it would be easier for me to wire the bathroom onto the RCD side of the consumer unit than to bond.

Any advice would be much appreciated.

Thanks for your help.

 

[Taylortwocities]

If the rewire is being done to 16th edition then you must carry out equipotential supp bonding.
This is a requirement of the 16th and is irrespective of what (if any circuits) in the bathroom are RCD protected.

Its a different story for the 17th..

 

[marnerbird]

Thanks a lot for the quick reply.

Thats just jogged my memory, the person that told me about RCD for the bathroom had mentioned that.

Oh well, looks like I'm going to have to remove the homemade (not by me) sink vanity unit then to access the pipes !!

Cheers

 

[Taylortwocities]

You may be able to access the pipes in an adjacent (airing) cuboard. Dont forget bonding for lights, shaver skt, heater, etc etc

 

[Mike2007]

17th edition.
701.4415.2 Supplemetary equipotencial bonding.
second section; roman iii.
All extraneous-conductive-parts of a location are effectively connected to the protective equipotencial bonding according to reg 411.3.1.2

411.3.1.2 Protective equiptential bonding

In each installation main protective bonding conductors complying with Chapter 54 shall connect to the main earthing terminal extraneous-conductive-parts including the following:
(i) Water installation pipes
(ii) Gas installation pipes
(iii) Other installation pipework and ducting
(iv)Central heating and air conditioning systems
(v) Exposed metallic structural parts of the building

There is that concise enough!

 

[Taylortwocities]

The re-wire is being done to the 16th edition, .

Thanks for the extract from the 17th though,

 

[conny]

This probably seems like a silly question to most of you, but as I have been out the installation side for over 25 years I would like to ask it anyway.

If the 17th regs are now in force how can you do a job to the 16th? Surely it has to be up to current regulations? Or can you get round this by having started the job before the start date of current regs?
This is not a joke question by the way, just trying to get back 'in the groove' so to speak.
Thanks.

 

[marnerbird]

Hi Conny,

I'd logged my building notice with the LABC before the 1st July when the 17th came into effect to ensure that I could rewire to the 16th. As long as the notice was received by them before the 1st July I can rewire to the 16th. I don't even have to start the work before the 1st (although I have) as I can say that I'm designing the installation, which as far as I'm aware (I work for an M&E company) is sufficient to be able to rewire to the 16th after the 1st. Obviously, if I'd applied now it would have to be the 17th.

Hope this makes sense

 

[marnerbird]

Hi Taylortwocities,

I'd had a look in the airing cupboard but I think it will be easier to connect the bonding below the taps. The bathroom is going to be replaced in 6 months, so only has to be functional at the moment so I'm not to worried about dismantling the vanity unit. The sink is installed on some kitchen laminate, so I can prop that up with some 2"x"2 to the floor and batons on the wall.

One thing I did notice is that from the elctric shower, there is a 10mm earth coming from it. There is then an earth clip on the 10mm for the cold water supply to the shower, but the cable then runs to the earh block by the cut out (TN-S system). I thought the bonding should be run to the CPC in the light fitting or other electrical point in the bathroom. Is it best to strip out this cable and replace with 4mm and run this to the light fitting or is what is there ok ?

Thanks a lot for your advice.

 

[conny]

Aha!
Thanks Marnerbird, I understand now. Just a bit puzzled thats all.

 

[sm1thson]

before the 1st July when the 17th came into effect to ensure that I could rewire to the 16th.

the 17th came in at the beginning of the year (feb?) the 16th went out at the end of june.

I cant understand why people go to measures to 'ensure that' they can wire to the 16th. i understand when moving a lightswitch wired to an old fusebox but if your doing significant work why pay all that money and make it to an old standard when you could pay a bit more and have it bang up to date, in 5-10 years your rewire will feel more outdated.

 

[marnerbird]

The reason I wanted it wired to the 16th is that I lived abroad for 4 years and the apartment we rented had the same set up as a 17th edition board and the amount of times the RCD's tripped was unbelievable. I only needed to have the iron on, TV and another appliance (all brand new appliances) and the whole lot went off.

I can appreciate the reasoning for RCD protection on every circuit, but it is something I didn't want.

How old are re-wireable fuses ? They are still everywhere and people are still happy with them.

 

[securespark]

Electrium (parent company of Wylex) are still churning them out in Wythenshawe, Manchester...

 

[sm1thson]

The reason I wanted it wired to the 16th is that I lived abroad for 4 years and the apartment we rented had the same set up as a 17th edition board and the amount of times the RCD's tripped was unbelievable. I only needed to have the iron on, TV and another appliance (all brand new appliances) and the whole lot went off.

I can appreciate the reasoning for RCD protection on every circuit, but it is something I didn't want.

sounds like it had an N-E fault (or possibly some other fault), on a typical 16th board the situation would still be the same as plugged in appliances would be on the same RCD, but i guess you are saying that at least you wont get nuisance tripping on the other circuits (at different times with them been on a different RCD).

I guess RCDs tripping due to external influences could be a valid reason to not like them, but that is rare and generally they trip because there is a fault, inconvenient as having a fault show in early stages is i still believe its a good thing.

The more circuits get separated onto more RCD's the less nuisance tripping will be a problem. Naturally there is a cost to this and as more RCD's and RCBO's are been used now the cost will come down.

Anyway thats enough said on that, it wasnt so much a dig at you but a lot of people are dragging out the 16th so i just used this opportunity to have my say.

 

[marnerbird]

I guess it could have been a N-E fault, but this happened in a lot of peoples homes in Spain and these where quite new properties on the costa blanca. Not sure if their regs are as good as ours ?

Like I said, I do appreciate the use of RCD's protecting all circuits and in my case, not having to put in supplementary bonding in the bathroom would have been a little help, although the job wasn't as difficult as I first thought it was going to be.

If I was doing this in a couple of years time, I would hope that RCBO's had come down enough in price as I would prefer to use those for each circuit as they seem the best option against nuisance tripping and losing half your circuits, but at £30-£40 a pop at the moment it would have cost me over £400.

Anyway, as we're now past the 1st July, this debate will die a death as no one has a choice now.