Bonding Pool and Spa / Bonding Stainless Steel Shower Tray

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Tiger
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Bonding Pool and Spa / Bonding Stainless Steel Shower Tray

Post by Tiger »

Hi Everyone,

I am asked to quote for a second dwelling in the back yard. When I visit the site today and find hat one pool with spa is in building as well and the foundation has been done(but the concrete for the brick wall has not been done yet). Well, my understanding is that the reinforcing mesh of the pool foundation needs to be bonded according to Clause 5.6.2.6.2 in 3000. But due to the current situation, is it ok to bond the starter bar instead? please see the photo below

Also, regarding the Stainless Steel Shower tray, my understanding is that as long as the water pipes to the mixer are PVC, then the metal tray need not be bonded, just like sink. Am I correct?

Many thanks in advance for the help. Cheers.
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DougP
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Re: Bonding Pool and Spa / Bonding Stainless Steel Shower Tray

Post by DougP »

Yes, bonding the starter bar should be fine. You can test the resistance to other parts of the reinforcing with your low-ohm meter to make sure it's working. Maybe you need to connect to a couple of points. The connection to the bar does not need to be accessible. You should obviously try and make it mechanically sound, and try to prevent corrosion etc.

Additionally, the bonding would also need to be connected to the reinforcing in any concrete pool surround, and any metal item larger than 100mm in any direction, which are within arms reach (1.25m) of the pool. So check if there's anything on the existing house that needs bonding as well.
Take a look at 5.6.2.6.1 through to 5.6.2.6.5 - you may have to run multiple bonding conductors to different locations, and take them to the connection point.
With regard to the connection point, the bonding conductor from the connection point only needs to connect to the earth of the power circuit for the pool equipment (in the pool shed?) or the pool equipment DB if there is one. It doesn't need to run back to the house switchboard.

A metal shower tray (or sink bench etc) never needs to be bonded. If the pipes are conductive from the ground to a point where they are accessible inside the building, it is the pipe that needs to be bonded as close as possible to where it comes out of the ground. The items that are connected to the pipe (like a metal bench) do not need to be bonded. In some cases things like a metal splashback might needs to be earthed, if there are electrical accessories mounted into it, but that is different from bonding requirements.
If the tray had a conductive pipe which was continuous and had contact with the ground, then it is the pipe that needs bonding as close as possible to where it comes out of the ground.

Also things like metal pipes connected to hot water cylinders, or gas califonts etc, don't need to be bonded as they are connected to the earthed equipment.
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Tiger (Fri Oct 02, 2020 11:42 pm)
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Tiger
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Re: Bonding Pool and Spa / Bonding Stainless Steel Shower Tray

Post by Tiger »

Thank you very much for the very fast reply, Doug!

Just three more questions from your reply:

1. Bonding conductor normally shall have a cross-sectional area not less than 4 mm2, which means the common powerpoint cable, 2 x 2.5mm2 + E, are not suitable for the use to connect as bonding conductor. I understand there is an exception in 5.6.3.2 (b), but it is for the multi-core flexible cord, not multi-core cable.

2.You mentioned

A) "in some cases things like a metal splashback might needs to be earthed, if there are electrical accessories mounted into it, but that is different from bonding requirements."

Also you mentioned,

B) "Also things like metal pipes connected to hot water cylinders, or gas califonts etc, don't need to be bonded as they are connected to the earthed equipment."

So my understanding is that

1). for B) if the extraneous conductive parts/fittings are in contact with the exposed conductive parts of the electrical equipment which has been earthed, then bonding is not necessary? (even if the resistance exceeds 0.5ohms). For one more example, the sink where the Food Waste Disposer (like Insinkerator) is installed.
2). For A) if the extraneous conductive parts/fittings are not in contact but adjacent to the exposed conductive parts of the electrical equipment which has been earthed, then bonding is necessary?

3.Regarding whether the bonding to metal or S/S benchtop in the kitchen area is necessary or not, I have read that, if the benchtop it bolted into the ground, then it needs bonding, if the benchtop on rubber wheel, like "floating", then bonding is not necessary. May I know your opinion?

Thanks again.
Cheers
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DougP
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Re: Bonding Pool and Spa / Bonding Stainless Steel Shower Tray

Post by DougP »

1. The earth to the power point is not a bonding conductor, so the 4mm2 minimum doesn't apply. The bonding conductor can connect to the circuit earth, in order to be connected to the installation earthing system. The 4mm2 minimum is more about mechanical strength, than CCC or resistance.
The clauses is quite clear on where the bonding conductors can be connected.

A. Note that I said earthing, not bonding. Look at 5.4.6.1 for the answer.
B. Look at 5.6.2.3 exception.

3. A bench doesn't need bonding, regardless of being bolted to the ground (I presume you mean floor?).

5.6.2.1 and 5.6.2.2(a) and (b) explain the general requirements for bonding (other specialised requirements might apply in other places).
Basically bonding is required when something conductive (like a pipe) is in contact with the earth outside the building, and continuous to inside the building where it is accessible. So the bench in your example isn't coming from outside the building.
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