How how to bond existing in ground pool?

[SteB88]

Hello all,

First post for me, a very frustrated DIYer whos leaving in a country (Czech Republic) where its near impossible to find an English speaking electrician who knows what they are talking about.

My issue is that the company who installed our vinyl pool a few years back clearly didn't do something correctly with the electrics and the result is that you can get a little shock when touching the pool water and the surrounding deck at the same time. We have already paid for three different 'professionals' to take a look, but all claim it makes no sense.

I've spent hours researching and believe that this is due to equipotential bonding, or lack there of. I'm 100% sure the rebar around the pool was never bonded to any of the other pool equipment.

Firstly, looking for some professional opinions if that makes sense?

Second, looking for some clarification on how to best go about resolving. Important to note, i do not want to do this myself, but after past experience i want to understand it so as to be sure its done properly.

The setup:
In ground pool with a light fixture.
Service pit with all of the equipment is 70cm from the pool
Heat pump is 4m from the pool and obviously connect to the service pit.

What i know is that the heat pump, water pump, and even the water pipes (some lug in them) all have earth wires leading back to the main fuse board. This fuse board leads to another in the garage which finally leads to the main board in the house and all are certified as up to standard.

My idea, and its just an idea, was to chip away the concrete at the four corners to the pool to expose the rebar. No idea then if that can then just run to the heat pump, which is easily accessible, or if it needs to go back to the service pit (headache).

Appreciate you taking the time to read, and even more so for any advice you may have.

Regards,
Steve

P.S If there is an electrician from Czech Republic who's reading and knows what they are talking about, you can have the job

 

[SteB88]

My suspicion is this is a TN-C(S) supply and that the supply earth is seeing several volts of neutral drop, especially if it is rural. However, it might be worse, a TT system without an (functioning) earth rod and the pool is becoming the route for all leakage!

Can the original poster put up some photos of the power supply arrangement and main panel/fuse box so we can guess?

The other thing not mentioned by the OP by raised by @Megawatt is the supply to the pool electrics has to be on a RCD/GFCI. Might as well confirm this while other things are being discussed.

In terms of earth bonding to the concrete then it might well be simpler to just drill and insert some rods at each corner in the USA-style. But as @Mike Johnson says if it has rebar in there, that would be a very good earthing system if attached at any point that can be accessed (assuming without too much difficulty).

Attached some pics of the fuse boards we have. the run is House > Garage > Pool.
How do i check RCD/GFCI? keeping in mind I'm not an electrician

About earthing the Rebar.. can this actually do any harm or make things worse? wondering if to just get someone to give it a go and see, but then i'm worried it might make a different issue.

 

[SteB88]

I don't understand why bonding at all four corners is required, all the reinforcing bars in the concrete are connected to each other with tying wire, I would have thought one connection would be sufficient, conveniently in the pit, but then your are reliant on the pool being constructed correctly, if not then even four rods may not do it, but I would try connecting in the pit before going to the expense and work of putting in four rods.

Makes sense, thanks for the feedback Mike.

 

[SteB88]

I don't understand the reference to DC from your person who inspected the situation.

Nor me, but i checked once again and its clear written in his very short report that he gave back to the pool company. Would share but its not in English.

 

[pc1966]

Attached some pics of the fuse boards we have. the run is House > Garage > Pool.
How do i check RCD/GFCI? keeping in mind I'm not an electrician

More detailed photos might help!

It looks as if there are RCD at each of the boards, but it is not really possible to say from that level of detail. However, it all looks reasonable quality equipment so I would imagine so.

About earthing the Rebar.. can this actually do any harm or make things worse? wondering if to just get someone to give it a go and see, but then i'm worried it might make a different issue.

Electrically, no.

However, I have no idea of the risk of causing physical damage to the pool arising from trying to access it!

If you are sure there are no buried service pipes or cables around the pool it might be safer to put in rods at the corners beyond the concrete area. Typically rods have to be deep to be effective, say 2-3m, and often they are in 1.2m segments that can be screwed together as they are driven in.

If you are unsure about buried stuff and are willing to dig down manually (and with care in case you do meet something) then by time you have dug a post-sized hole to around 1m down you are probably clear of any buried service cables & pipes.

Here are a couple of UK suppliers of earthing stuff, more from a lightning protection point of view:

Earthing Archives - Kingsmill Industries

kingsmillindustries.com

Home

A.N. Wallis is the number one supplier for all your earthing, lightning protection and surge protection equipment.

www.an-wallis.co.uk

 

[pc1966]

Incidentally if putting in a ring of conductor around the pool you generally can and should bury is a bit under the surface, less likely to get noticed/stolen and contributes better to the earth conductance. At the corner rods you can have inspection pits to access the wire and rod fixing bolt, etc.

 

[Mike Johnson]

You can get Reinforcing rod earth clamps, I would suggest going this route first as it is the easiest option, find a location away from other supplies/services, LED Lights, Heat pump etc, and dig into the concrete preferably without a concrete breaker to save compromising the structure, the reinforcing should only be 50mm (2") below the surface of the concrete, you will have to expose the whole surface of the bar to get the clamp on, attach at least a 16mm earthing cable and make good with a resin concrete compound to protect the reinforcement, run this back to the fuse board main earth terminal.

It is quite normal for the clamp not to be accessible in earthed RC structures.

 

[Megawatt]

My suspicion is this is a TN-C(S) supply and that the supply earth is seeing several volts of neutral drop, especially if it is rural. However, it might be worse, a TT system without an (functioning) earth rod and the pool is becoming the route for all leakage!

Can the original poster put up some photos of the power supply arrangement and main panel/fuse box so we can guess?

The other thing not mentioned by the OP by raised by @Megawatt is the supply to the pool electrics has to be on a RCD/GFCI. Might as well confirm this while other things are being discussed.

In terms of earth bonding to the concrete then it might well be simpler to just drill and insert some rods at each corner in the USA-style. But as @Mike Johnson says if it has rebar in there, that would be a very good earthing system if attached at any point that can be accessed (assuming without too much difficulty).

When I said drive ground rods at each corner I meant for the OP to do his own bonding to all metal parts on his pool

 

[Pretty Mouth]

We actually disconnected the light as the first thing to check and be sure it was not the cause. Issue still there though

Just a thought: Have you tried carrying out the 'tingle test' with all power to the property isolated?

 

[SteB88]

Quick update on this. We had everything tested once again and still the same. We installed a bonding wire around the grid every 2 feet after chipping into the concrete and believe it or not, this actually made things worse

The theory now is that the salt water in the pool reacts with surrounding ground to act like a battery.

 

[Mike Johnson]

There should not be any salt water outside the pool, unless they put it there, the salt is to supply a generator with platinum plates that have an electrical charge running through then to turn the salt into Chlorine, so even if its pool discharge it should only have about 4000ppm in the water, so I doubt very much it that is the problem.

 

[pc1966]

Quick update on this. We had everything tested once again and still the same. We installed a bonding wire around the grid every 2 feet after chipping into the concrete and believe it or not, this actually made things worse

Can you post some photos of how this was done?

Can you clarify if the bonding wire is attached to the rebar, or to the supply CPC (or both)?

Are there any other earth wires/rods other than bonding to the pool's structure?

 

[Mike Johnson]

Do you have any metal structures bolted down onto the deck?

 

[SteB88]

There should not be any salt water outside the pool, unless they put it there, the salt is to supply a generator with platinum plates that have an electrical charge running through then to turn the salt into Chlorine, so even if its pool discharge it should only have about 4000ppm in the water, so I doubt very much it that is the problem.

Well, its an overflow pool so always pretty much filled to the brim, so when my two kids go jumping in and out constantly the deck gets pretty saturated.

 

[SteB88]

Do you have any metal structures bolted down onto the deck?

None actually, and there is no metal ladder either, its inbuilt steps.

 

[Pretty Mouth]

Quick update on this. We had everything tested once again and still the same. We installed a bonding wire around the grid every 2 feet after chipping into the concrete and believe it or not, this actually made things worse

The theory now is that the salt water in the pool reacts with surrounding ground to act like a battery.

@SteB88 , did you try as per post #23, with all power isolated?