Been asked to look at outdoor socket for spa. A brief perusal of M.I. recommends the installation of equipotential bonding in 2.5mm² solid copper. Now apart from the idea of non flexible cable, what purpose may it truly serve. It is supplied with a cable that has a 10ma trip in it. However we must take account of M.I. I suppose if the earth came adrift in the cable then the bonding might help. The manual has that kind of writing/grammar that reminds of chinese product instructions. The client was somewhat taken aback and insisted all his friends have not had to have this done when their electrician installed theirs. I checked water and gas bonding (as you do) and found the earth clamp under the sink without a label and loose. Probably does not help for safety in this case. Recommended urgent attention to this matter. There is a stud on the bottom of the pump/heater for this purpose. I know if it was me I would bond it, what do y'all think?
I'm definitely not qualified to answer this but are there any BS7671 exceptions for equipotential bonding pools?
In Australia and America where they have more outdoor pools I think they are more hot on equipotential bonding and would be taken into account at design stage, they also have alot more interest in stray voltage and pools outside.
from this American web site about a accident with stray voltage in a pool the woman says "In England, they have ground fault connectors on everything," says Ritz "Guess how many fatalities they're reporting? None."
Well suppose the element ruptured for the water heater. Live would go to earth. Suppose the cable had deteriorated/been damaged and the earth was detached. If in this admittedly unlikely scenario a shock was received by the spa user, and you had ignored the M.I. how would that work out for you? The spa is on a wooden plinth. The pump/heater has a bonding bolt on the bottom of the unit. How for instance would I justify not taking into account the M.I.?
I wonder if the bonding option is for countries that don't always have an 3-pin connector with earth?
Certainly I have seen more than one bit of musicians' equipment with badly damaged cables that had, or were at risk of, loss of CPC so it is a real risk (but not so common if you don't have strategically shaved gorillas carrying gear by the power cables) and a possible reason for having a 2nd CPC link.
I guess the other thing is to use the house CPC circuit or a separate earth rod, etc.
Hi Vort - not saying not to bond, but perhaps have a looky look at Reg 544.2.5 . This is also talked about in GN8 p101 (of my now defunct 17th edition).
Well suppose the element ruptured for the water heater. Live would go to earth. Suppose the cable had deteriorated/been damaged and the earth was detached. If in this admittedly unlikely scenario a shock was received by the spa user, and you had ignored the M.I. how would that work out for you? The spa is on a wooden plinth. The pump/heater has a bonding bolt on the bottom of the unit. How for instance would I justify not taking into account the M.I.?
But that 'bonding bolt' (pump/heater) is on a conductive part, not an extraneous conductive part, you are not bonding it, you are simply doubling up the earth connection. Bonding takes place between conductive parts and extraneous conductive parts.
Where are the ECP's here?
The fact the Manufacturers instructions say 2.5mm for the bonding is completely wrong anyway as it’s way undersized for say pme arrangements. That’s assuming it’s main protective bonding of extraneous conductive parts and not supplementary equipotential bonding?
seems like a bit of a grey area - there are no exceptions as I understand?
but even googling the regulatory bodies uk will have a reply that that somehow doesn't answer the original question but takes you somewhere else.
[automerge]1594206373[/automerge]
but its a socket? and should be Class II so wouldn't and shouldn't be bonded
Good point I guess if it is a socket? and metal it should be bonded technically, you aslso raise a good point in earlier post as your surrounded by mass of earth anyway etc
Thanks all for your input. Really speaking I am/was doubtful about this requirement. It is always nice though to consult the hive mind for some pragmatic views. What fuses my mind is M.I. requiring this highly dubious safety method.
Thanks all for your input. Really speaking I am/was doubtful about this requirement. It is always nice though to consult the hive mind for some pragmatic views. What fuses my mind is M.I. requiring this highly dubious safety method
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