Metal bath

[AndersonC]

I'm re-plumbing the bathroom from lead to copper and will need to re-connect my supppementary bond earth tags between the H&C pipes. Whilst being stuck under the bath I noticed this is not directly connected to the pipes by an earth wire.

My understanding is that the bath should be earthed. Quite why I don't know as there is no electric in the room other than the light which is switched on from the landing. Anyway, can I just connect the bath to the cold water pipe with an earth cable?

Thanks for your advice.

 

[plugwash]

As long as the pipes entering the room and the earth connections of any circuits supplying the room (just the light in this case) are connected together you shouldn't need to bond the bath itself.

 

[Spark123]

I know it says in the IEE regs that metal bathtubs require supplementary bonded although I would question the validity of this on the understanding that unless the bathtub is in contact with another item such as a metal building structure which making it extraneous, then as the metal pipes which are making it extraneous are already bonded imo there is little to be gained by actually bonding the bathtub. http://www.iee.org/Publish/WireRegs/EarthingPlasticPipes.pdf.
Your supplementary bonding should connect together all extraneous metalwork and the protective conductors of circuits supplying equipment in zones 1,2,3.

 

[securespark]

Sometimes there are insulating washers seperating the pipework from the body of the bath.

 

[Spark123]

Sometimes there are insulating washers seperating the pipework from the body of the bath.

If so this can mean the bathtub is effectively electrically floating (subject to adequate resistance to the MET), which imo is better than bonding it.

 

[securespark]

However, that "isolation" cannot be guaranteed total, so bonding is essential.