Im suffering a bit of Brain Fog this morning - but clause 5.6.2.6.1(b) in 3000 has me a bit stumped. "The following shall to be epuipotentially bonded (b) Any exposed conductive parts of the electrical equipment that are not separated from live parts by double insulation and that are in contact with pool water, including water in the circulation of filtering system"
In my mind that would make it a class 1 appliance, which means the exposed conductive parts must be earthed anyway. So what is the use of a bonding cable attached to an already earthed casing??
Or is this clause specifically for ELV equipment, which may not have an earth??
Pool Equipment Bonding 5.6.2.6.1 (b)
Re: Pool Equipment Bonding 5.6.2.6.1 (b)
Have a look at 5.6.3.2(b) exception. The bonding conductor can just be the earth in the supply cable to the pump or other equipment.
Re: Pool Equipment Bonding 5.6.2.6.1 (b)
True the PECs we install primarily for purposes of fault protection can also serve an equipotential bonding function.
So yes, if the pool equipment is Class I and so has a PEC; then the PEC can also act as a EBC (and because incorporated into the cable instead of being a separate conductor, doesn't need to be 4 mm2 - which is what that Exception is about).
But if the pool equipment is Class II, that won't work - yet any accessible conductive parts still should be bonded.
Not to deal with faults internal to the equipment itself; but to deal with other scenarios that could result in them being at a significantly different potential from other, earthed, equipment in the vicinity.
So yes, if the pool equipment is Class I and so has a PEC; then the PEC can also act as a EBC (and because incorporated into the cable instead of being a separate conductor, doesn't need to be 4 mm2 - which is what that Exception is about).
But if the pool equipment is Class II, that won't work - yet any accessible conductive parts still should be bonded.
Not to deal with faults internal to the equipment itself; but to deal with other scenarios that could result in them being at a significantly different potential from other, earthed, equipment in the vicinity.
Re: Pool Equipment Bonding 5.6.2.6.1 (b)
Ok Im still a bit confused - I can't see the exception in my standards, not that it matters. The class 1 appliance already being earthed negates the need for a seperate bond cable, that makes sense.
I can also understand the need for a bond onto conductive surfaces that are in the same system as Earthed equipment to keep all conductive surfaces at the same potential, that also makes sense.
But the way the clause is written is a bit confusing.
"Any exposed conductive parts of the electrical equipment that are not separated from live parts by double insulation and that are in contact with pool water, including water in the circulation of filtering system"
I was under the impression that if the equipment was double insulated, then everything else would be separated by double insulation within the equipment (including pool water circulating throughout the system). Therefore no need for bond?? Because all conductive parts of the electrical equipment are separated from live parts by double insulation.
Im obviously missing something??
I can also understand the need for a bond onto conductive surfaces that are in the same system as Earthed equipment to keep all conductive surfaces at the same potential, that also makes sense.
But the way the clause is written is a bit confusing.
"Any exposed conductive parts of the electrical equipment that are not separated from live parts by double insulation and that are in contact with pool water, including water in the circulation of filtering system"
I was under the impression that if the equipment was double insulated, then everything else would be separated by double insulation within the equipment (including pool water circulating throughout the system). Therefore no need for bond?? Because all conductive parts of the electrical equipment are separated from live parts by double insulation.
Im obviously missing something??
Re: Pool Equipment Bonding 5.6.2.6.1 (b)
I think what you're missing is that this bonding is not related to hazards arising from the electrical equipment.
It's about hazards arising from the pool water being at significantly different earth potential than the installation's earthing system.
In crude terms, and for an extreme case, the pool water becomes "live" with respect to earth; to whatever degree and for reasons other than a fault within the particular equipment concerned.
If the pool water becomes live for any reason; then everything conductive that touches the pool water also becomes live.
So for our example, the pool pump's impellor housing becomes live.
If the pump happens to be Class I; then the impellor & housing will be effectively bonded to installation earthing system by the PEC for the pump circuit - and there can be no significant potential between the housing and other earthed items.
But if the pump is Class II, it won't have a PEC; and the impellor housing will sit there being "live" compared to installation earth.
Unless we bond it by a separate equipotential bonding conductor (EBC), minimum 4 mm2 i.a.w clause 5.6.3.2.
We could connect that EBC to the PEC of the pump curcuit.
But better to connect it to the pool's equipotential bonding system
And yes, the clause you're looking at is confusing.
It says you have to bond things that are not separated by DI;
which is arsy-boo because clearly those things are likely to already be bonded via the PEC for the equipment.
(and as Doug pointed out, the clause about minimum size for the bonding conductor allows this even for PECs smaller than 4 mm2)
The real problem is the opposite case; it's the stuff that does have DI and therefore is not connected to a PEC that needs to be bonded.
So yes, whether equipment is Class I or Class II IS relevant to whether bonding is needed from a safety perspective at the time the equipment is installed. Just that this particular re-writing of the clause got it wrong (my opinion) back in 2000.
I believe the word "not" should never have been there.
It should have been the accessible conductive parts of Class II (DI) equipment that had to be bonded; 'cos the Class I stuff would be de-facto bonded by the equipment's PEC.
The error survived the many amendments since; until it was finally corrected in the 2018 edition.
Not because it was recognised as an error; but because the Committee recognised that this particular trigger condition for bonding could change over the life of the installation. And if it changed for the worse; there was a strong likelihood that no-one would notice, let alone do anything.
Regardless of which way the trigger condition operates; if bonding is required for one condition and not required for the other , and the condition changes; then the requirement for bonding changes.
But unless the person who changes the condition knows firstly knows that there might be a bonding requirement; and also understands the Class I vs Class II differences, they won't know they've made a difference.
To the average plumber, a pump is just a pump. And if it plugs in, they don't need an electrician.
And even if they call an electrician to disconnect / reconnect a directly-connected item; will that electrician think about whether a simple pump swap would change the bonding requirements?
So the "trigger" condition was removed; to make direct bonding of exposed conductive parts mandatory regardless of whether the equipment that happens to be in place at the time is Class I or Class II.
Bonding is not well understood by our industry. Or even by many of the people who set the rules.
If we look back further than 2000; there were no special rules for pool bonding in NZS 3000:1997.
But we did have to bond urinals, shower trays, kitchen benches, and other things; just because of what they were, and not on any sound basis of risk of touch voltage existing. And 20 years after they were removed, some people think those requirements still exist!
The trick is to stop thinking about normal operating conditions; or even faults within equipment.
Many of the faults that can cause rises in "earth" potential will not even be within the installation.
It's about hazards arising from the pool water being at significantly different earth potential than the installation's earthing system.
In crude terms, and for an extreme case, the pool water becomes "live" with respect to earth; to whatever degree and for reasons other than a fault within the particular equipment concerned.
If the pool water becomes live for any reason; then everything conductive that touches the pool water also becomes live.
So for our example, the pool pump's impellor housing becomes live.
If the pump happens to be Class I; then the impellor & housing will be effectively bonded to installation earthing system by the PEC for the pump circuit - and there can be no significant potential between the housing and other earthed items.
But if the pump is Class II, it won't have a PEC; and the impellor housing will sit there being "live" compared to installation earth.
Unless we bond it by a separate equipotential bonding conductor (EBC), minimum 4 mm2 i.a.w clause 5.6.3.2.
We could connect that EBC to the PEC of the pump curcuit.
But better to connect it to the pool's equipotential bonding system
And yes, the clause you're looking at is confusing.
It says you have to bond things that are not separated by DI;
which is arsy-boo because clearly those things are likely to already be bonded via the PEC for the equipment.
(and as Doug pointed out, the clause about minimum size for the bonding conductor allows this even for PECs smaller than 4 mm2)
The real problem is the opposite case; it's the stuff that does have DI and therefore is not connected to a PEC that needs to be bonded.
So yes, whether equipment is Class I or Class II IS relevant to whether bonding is needed from a safety perspective at the time the equipment is installed. Just that this particular re-writing of the clause got it wrong (my opinion) back in 2000.
I believe the word "not" should never have been there.
It should have been the accessible conductive parts of Class II (DI) equipment that had to be bonded; 'cos the Class I stuff would be de-facto bonded by the equipment's PEC.
The error survived the many amendments since; until it was finally corrected in the 2018 edition.
Not because it was recognised as an error; but because the Committee recognised that this particular trigger condition for bonding could change over the life of the installation. And if it changed for the worse; there was a strong likelihood that no-one would notice, let alone do anything.
Regardless of which way the trigger condition operates; if bonding is required for one condition and not required for the other , and the condition changes; then the requirement for bonding changes.
But unless the person who changes the condition knows firstly knows that there might be a bonding requirement; and also understands the Class I vs Class II differences, they won't know they've made a difference.
To the average plumber, a pump is just a pump. And if it plugs in, they don't need an electrician.
And even if they call an electrician to disconnect / reconnect a directly-connected item; will that electrician think about whether a simple pump swap would change the bonding requirements?
So the "trigger" condition was removed; to make direct bonding of exposed conductive parts mandatory regardless of whether the equipment that happens to be in place at the time is Class I or Class II.
Bonding is not well understood by our industry. Or even by many of the people who set the rules.
If we look back further than 2000; there were no special rules for pool bonding in NZS 3000:1997.
But we did have to bond urinals, shower trays, kitchen benches, and other things; just because of what they were, and not on any sound basis of risk of touch voltage existing. And 20 years after they were removed, some people think those requirements still exist!
The trick is to stop thinking about normal operating conditions; or even faults within equipment.
Many of the faults that can cause rises in "earth" potential will not even be within the installation.
Re: Pool Equipment Bonding 5.6.2.6.1 (b)
Thanks AlecK. Your'e right. If you take the 'not' out of the clause, then it totally make sense that all DI equipment must be bonded. But (to me) having the 'not' in the clause makes it sound like DI equipment doesn't need bonding because all live parts are separated by DI, therefore doesn't require bonding.
Thanks for clearing the up
Thanks for clearing the up
Re: Pool Equipment Bonding 5.6.2.6.1 (b)
I'm reasonably confident that "not" shouldn't be there.
But 20 years is a long time for an error like that to not be noticed.
Especially when other aspects of that set of clauses have been amended several times.
However while we can get in trouble for not bonding; there nothing to lose by bonding when you don't have to.
So maybe the answer is to ignore the "trigger" condition; and just bond regardless
But 20 years is a long time for an error like that to not be noticed.
Especially when other aspects of that set of clauses have been amended several times.
However while we can get in trouble for not bonding; there nothing to lose by bonding when you don't have to.
So maybe the answer is to ignore the "trigger" condition; and just bond regardless
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