Am I right in thinking that if the CU has an RCD fitted, there is no need for supplementary bonding and therefore there is no need to earth the bath.........all plumbing pipes are copper except for flexibles joining the copper to the taps.
Earthing a steel bath if fusebox has an RCD?
- Thread starter DIYedboy
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Not quite
701.415.2 basically says
30mA RCD for ALL circuits that are in the bathroom
and
All circuits in the bathroom meet the requirements for ADoS as set in the regs
and
All extraneous conductive parts are properly connected to earth.
701.415.2 basically says
30mA RCD for ALL circuits that are in the bathroom
and
All circuits in the bathroom meet the requirements for ADoS as set in the regs
and
All extraneous conductive parts are properly connected to earth.
Baths do not require earthing or bonding regardless of there being an RCD or not.
You should never earth the bath.
You would only bond it IF IT itself is an extraneous-conductive-part.
You would only bond it IF IT itself is an extraneous-conductive-part.
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How so?
If the bathtub is isolated from earth and the only extraneous parts connecting to it are already bonded (or the installation meets the 17th edn for not requiring bonding) there is little to be gained by bonding the bathtub.
There might be - but would that qualify it as an extraneous-c-p?
Kind Regards, John
Why does it matter BAS? If it hasn't got a connection it will be electrically floating, if it has a connection (good or bad) to the pipes then providing they are already compliant I don't see an issue.
There used to be a good write up on the IET website regarding this when the 16th edn regs were in place but I think it has now disappeared.
There used to be a good write up on the IET website regarding this when the 16th edn regs were in place but I think it has now disappeared.
Are these metal or whatever the non-metal ones are made of?
Yes.
Not "effectively connected to the PEB" - 701.415.2(vi) Edited for purposes of omitting RCD and
in effect bonded with a poor connection.
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A bath is not an extraneous conductive part, and cannot introduce a potential into the bathroom.
Pipes connected to it might be, but those pipes would be bonded, not the bath itself.
The same apples to radiators and towel rails - they are not ECPs either as they are fully contained within the room. Pipes connected to radiators may require bonding.
Pipes connected to it might be, but those pipes would be bonded, not the bath itself.
The same apples to radiators and towel rails - they are not ECPs either as they are fully contained within the room. Pipes connected to radiators may require bonding.
If someone drops a double insulated appliance ( i.e. with no earth connection ) that is switched on into a plastic bath of water then the potential of the water will be about mid way between Neutral and Live ( circa 120 volts ). No protective device will be operated. The same lack of operation of protective devices would happen if the bath was metal but not earthed and had no conenction to metal pipes.
The risk of someone dropping a live double insulated appliance into a bath of water is a small but not insignificant risk.
With teh water at 120 volts any touching the water in the bath and and earthed ( or bonded ) pipe ( or nay other earhted or bonded item ) will get a shock. An RCD if fitted might operate quickly enough to reduce the duration of the shock to one that is short enough to not cause non reversible damage to the person.
My preference would be to earth or bond the bath so that the RCD operates when the appliance drops into the bath water.
The risk of someone dropping a live double insulated appliance into a bath of water is a small but not insignificant risk.
With teh water at 120 volts any touching the water in the bath and and earthed ( or bonded ) pipe ( or nay other earhted or bonded item ) will get a shock. An RCD if fitted might operate quickly enough to reduce the duration of the shock to one that is short enough to not cause non reversible damage to the person.
My preference would be to earth or bond the bath so that the RCD operates when the appliance drops into the bath water.
It doesn't have to be earth potential.
What is the difference between an (external) extraneous-c-p with a resistance of <23kΩ (or >1666Ω) to the MET and a bath with a similar resistance to a bonded pipe with regard to R<50/Ia and/or RCD omission?
[assuming you mean 701.415.2(vi)] ... But, by answering 'Yes', you've created a circular argument - 701.415.2(vi) only applies to extraneous-c-ps, so you can't use it to define whether or not something is an extraneous-c-p, can you?!
A (metal) bath can surely only be an extraneous-c-p ("liable to introduce a potential....") if it is in electrical continuity with something which enters the property from outside and that 'something' is not itself already bonded. A poor connection to something bonded does not make it an extraneous-c-p if it was not an extraneous-c-p in the first place.
Kind Regards, John
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