Earth Bonding - Is this OK?

[CraigFa]

Hi,
Doing the bathroom up and noticed there seems to be no earth bonding.

I was therefore going to bond the radiator pipes then run a wire to the hot and cold pipes and then run wire to the shower earth terminal.

Is this Ok?

Or any other suggestions

Thanks

Craig

 

[ssray]

equipotential bonding should be a minimum of 10mm csa, the shower earth is rated to handel any current from that circuit only i dont think it would be wise to try and add to it.

proper sparks will be along in a mo` as i`m only in training.
Ray

 

[RMS]

You should cross bond hot and cold copper pipes and the radiator if fed by copper pipes. This should then be connected to all circuits entering the bathroom, i.e. shower and lighting circuits.

4mm earth wire will be adequate.

 

[davelx]

We're talking supplementary bonding here and it only needs to be 4mm. Note that supplemetary bonding does not connect back to the MET.

You should also bond to the CPC of the bathroom lighting circuit, BTW.

Bah - too slow!

 

[CraigFa]

So where as teh first reply said do not conncet to the shower terminal earth, you are now saying I should?

Bit confusing all this conflicting advice

 

[RMS]

The cpc of the shower circuit either at the pull switch or the shower terminals need to be connected to all other circuits in the bathroom and hot and cold pipe work in the bathroom. This is supplementary equipotential bonding. Everything will then be at the same potential reducing the chance of electric shock.

Example. Run a 4mm earth wire from your shower to behind the sink. Run one from your light fitting to behind the sink. Run one from your rad to behind the sink. Now connect a wire between hot and cold pipes behind the sink and connect the two other wires to either of these connections.

If any other circuits enter the bathroom then the cpc will have to be connected in the same way.

 

[JohnD]

So where as teh first reply said do not conncet to the shower terminal earth, you are now saying I should?

Bit confusing all this conflicting advice

The first reply was from a trainee (no offence intended).

10mm is used for the main bonds betweem the main earthing point by the meter, and the incoming metallic services (gas and water pipes) where they enter the house.

However, you are talking about a bathroom, which has Supplementary Bonding. this connects all metal pipes that enter the bathroom to the earthwire of all electrical circuits that enter the bathroom. These are all bonded together. this is typically the electric shower, lighting circuit, and immersion heater. Sometimes the circuit for a central heating pump and thermostst, if the airing cupboard is in the bathroom. If there is electric heating or shaver socket that is supplied by a different circuit, that too. You only have to bond each circuit, and each pipe, once, at the point where they enter the bathroom. You can bond them in the airing cupboard if it is adjacent.

See
//wiki.diynot.com/electrics:sp...l_bonding:supplementary_equipotential_bonding

http://www.iee.org/Publish/WireRegs...ring_wiring_matters_equipotential_bonding.pdf

 

[davelx]

Is this an electric shower mounted on the bathroom wall? If so, it should be bonded. If it's a power shower with the pump not in the zones then its CPC does not need to be connected to the bonding (though the pipes to the shower should be)..

OSG page 25:

"local supplementary equipotential bonding is required to be provided connecting together the terminal of protective conductors of each circuit supplying Class I and Class II equipment in zones 1,2, or 3, and extraneous conductive-parts in these zones"

edit: aargh - and again!

 

[davelx]

Is this an electric shower mounted on the bathroom wall? If so, it should be bonded. If it's a power shower with the pump and switch not in the zones then its CPC does not need to be connected to the bonding (though the pipes to the shower should be)..

OSG page 25:

"local supplementary equipotential bonding is required to be provided connecting together the terminal of protective conductors of each circuit supplying Class I and Class II equipment in zones 1,2, or 3, and extraneous conductive-parts in these zones"

edit: aargh - and again!

 

[CraigFa]

Hi,
Yes it is an electric shower.
Just noticed that the pipes in the kitcken are bonded. So do I need to bond the pipes that are for the tapes in teh bathroom

Therefore am I right is saying:

Bond shower earth terminla to pipe and the ensure taht other pipes coming of the shower feed pipe are bonded to main earth?


Thanks

Craig

 

[JohnD]

All the metal pipes, when they enter the bathroom. This includes radiator pipes, hot water pipes, cylinder pipes, hot and cold tap pipes (not just the shower pipe). If you have an old house with cast-iron or lead waste pipes, them too

to the earth of all the circuits that enter the bathroom.

All joined together.

Provided you have continuous copper pipe with soldered joints (i.e. permanent) then you can use the pipe as part of the bonding.

And you don't bond to "main earth". In the bathroom, you only bond to the earth wires of each circuit that enters the bathroom.

Any bonding in the kitchen is irrelevant to the bathroom. You have to bond in the bathroom too.

 

[CraigFa]

Thanks John.

Why don't you bond to the main earth (just for my own info)

If you bond all teh meatl pipes in teh bathroom where does this actually earth to.

Do you not need a wire going to an earth.

Sorry if these are silly questions

 

[JohnD]

Supplementary bonding in bathrooms:

the purpose is not to provide an earth.

It is to connect together all the metalwork that could introduce a voltage.

So if all the taps and the radiator and the shower are all connected together then even if there is a fault that raises them all to 250volts*, you cannot get a shock by touching any two of them. It would be like touching one end of a battery with two fingers. You can only get a shock if you touch two parts that are at different potentials (for example, both ends of a battery. And shorting them together with a piece of wire would mean that most current would pass through the wire, and there would be little left to pass through your fingers).

*This can happen, under certain combinations of fault, although the design is that this would cause a fuse to blow quite quickly. In an old and badly maintained installation, when such a fault might occur, you cannot depend on the design. In a bathroom, where you may have a lot of exposed wet skin, and a lot of exposed metal pipes and taps, the Supplementary Bonding gives an extra level of protection.

 

[CraigFa]

John
Excellent description - much appreciated

So hopefully I would:

Bond the shower feed pipe, the radiator feed pipes, hot and cold sink pipes

and no need to connect the shower earth cable to teh shower feed pipe

Thanks agiain for all your help

 

[JohnD]

... and no need to connect the shower earth cable to teh shower feed pipe

wrong.

"All metallic pipes that enter the bathroom to earth wires of all circuits that enter the bathroom".

The shower cable comes within "all circuits that enter the bathroom".

The shower pipe comes within "All metallic pipes that enter the bathroom"