Supplementary bonding. Quick question? Photos via name

[goooba769]

Now I have an electric shower and light circuit in the bathroom and I’m just wondering how you should run the 4mm earth cable for the supplementary bonding?
Should I run one from the light to the hot/cold pipe and then to the radiator pipe (I was going to connect this next door in the cupboard to rad pipes)?
Then do I run a second cable from the shower to the hot/cold + rad pipe?
I’m assuming any cable I run should not be cut at any point but should be a continuous length until the final point?

This is prob a simple one for some one cheers in advance for any pointers.

 

[davy_owen_88]

As of BS7671:2008 (17th edition) you do not need supplementary bonding in the bathroom provided that all the circuits are protected by a 30mA RCD and you have main equipotential bonding.

 

[goooba769]

davy cheers for that. I remember one side was protected by a 30mA RCD cant remember the otherside will have a nose later.

 

[Taylortwocities]

It wont have unless it was installed this year (2008).

You'd need to RCD/RCBO protect the bathroom circuit(s).

 

[goooba769]

Not long been in house but fuse board looks new ish but I dont think it was this year. Just remember seeing a 30mA RCD on the board. Could one side be 30mA and the other be different?
Or should I just do the bonding anyway just to save me finding out I need it when the lecky turns up and charges me to do it?

 

[davy_owen_88]

Unless you have a TT earthing arrangement (earthed using a rod driven into the ground somewhere on your property) then you will probably only have a single 30mA RCD. If you have a TT supply you will likely have one 30mA RCD for sockets/showers and a 100mA time delayed RCD protecting everything else.

Bonding has a very specific purpose and fitting it where it is not needed can actually be worse than not fitting it at all so finding out how your system is wired is vital.

If you post some pictures of your consumer unit, meter, main service fuse and then a wide shot of the whole area then I'm sure someone will be able to tell you everything you need to know.

 

[goooba769]

Right then Iv got some photos of the cons unit and ensuite.
Its got as davey mentioned 100mA RCD one side and 30mA RCD on the other. Im assuming I need supp bonding?
If so do I just run a contin 4mm cable from light to sink pipes to rad pipes and then a cable from shower earth to rad pipe.(rad connection will be next door in airing cupboard)?

Cheers for any comments.

If you click on my name you should be able to see photos I hope!

 

[Chri5]

Untitled

• goooba769
• 15 Sep 2008
• 1

You only have 1 x RCD, the other unit is the main isolation on / off switch for the CU.

Does the 6a circuit to the RHS of the RCD (centre) work the bathroom lights ?

If not the supp bonding will be required

 

[Chri5]

Actually it looks as if the 6A is a spare, because I can't see any wiring for it.

You could move the light circuit on to the 6A MCD on the RCD side and then both shower and bathroom lights would be on an RCD controlled circuit and thus no bonding required.

The circuit wiring, RCD and MCB would require a test and unfortunately the work should be notified under Part P

 

[goooba769]

Chris yes its a spare. That sounds as if it would save me some work!

cheers

 

[Chri5]

Make sure the neutral is moved to the RCD neutral bar otherwise you could experience the phantom of the RCD trip

 

[spanky]

Other conditions have to be met before the supplementary equipotential bonding can be ommitted - just having rcd protection ain't enough for the special location i.e. bathroom.


411.3.2 disconnection

411.3.1.2 extraneous conductive parts ......................
as far as i can see unless you can physically trace any extraneous conductive parts you will always have to check their resistance to each other and to any exposed conductive parts.

but thats just my understanding of it!


anyone wish to elaborate? I still trying to get my head round this one.