Swimming Pool Earthing

[carlyai]

Reading up lots on this several years ago, it seems that nearly all recommend a concrete and reo.   pool handrails etc should/must be earthed. Seems that is the practice in Thailand as well, even though pool lights transformers you buy from pool shops are made in a back shop in India and don't meet specs., so negating pool reo. earths.

Apart from that, our village (me) has experienced a probable PEA O/C neutral, so I was real worried about tying the pool to the main earth.

So I decided that as the pool pump and chlorenator are earthed (in the pool room and only blue pipes go to the pool) and the lights are thru a special pool transformer, I would not tie the pool to earth. The stairs are tied into the pool frame which is all tied together in a big block of concrete, so it is one big Faraday Cage, sitting in the ground. How is anything "live" going to zap swimmers? It seems planes are Faraday cages so lightning strikes go around the shell. Also linemen working on very high voltage wear Faraday Cage suites so they don't get zapped. If I earthed the pool to the main earth and we had another O/C PEA neutral, then all that current wanting to get back to the transformer by the easiest route may use the pool.

Can someone explain, with diagrams if possible why I'm wrong? Before (in an off topic post) I've been told 'you must do it' and 'it's complicated' but not why I must do it.

I am not an electrician and if I get a good reason, I'll do it. Thanks.

[Crossy]

Ah yes, the subject of whether to export a TNC-S "earth" to your swimming pool area, a rather complex subject, and there's no "one size fits all" solution.

 

i.e. You might be right, or equally you might be less right in your current solution, although with the pool equipment isolated from the pool itself (I'm assuming it's RCD protected - preferably 10mA) and low voltage lighting you're pretty safe.

 

Firstly, your pool re-bar and anything electrically bonded to it (hand rails etc.) is already a pretty good earth (look up Ufer ground or concrete encased electrode), what we need to determine is whether to connect that earth to the TNC-S earth.

 

It is imperative that whatever we do makes it impossible for a wet and rather conductive human to get between the TNC-S "earth" (the house electrical earth which can do horrible things in the case of an open-neutral) and "true earth" (the wet grass). So long as everything is at the same potential (even if that is not true earth) nobody dies.

 

Where is your pool located with respect to the house? And what electrical fittings (outlets, lights etc) are in the pool area? Is it possible to touch the pool metalwork (steps etc.) whilst standing on the lawn? A few drawings / photos would be useful.

 

 

[carlyai]

Thanks. Will have to wait till I get home for pics. I have about 1.5 》 m tiles all around the pool with only pool lights from a special pool transformer in the pool (12 V double insulated with fuses). 

The garage/pool room is a run of about 35 m  or 40 m from the main CU where the neutral and earth are linked as per regs.

I have the shed pool room feed to its own CU earthed with another earth rod. The only connection between neutral and earth is in the main house CU. Getting worried now.

When the mains power fails and the genset is running I do have a bit of current drawn on the neutral as I'm feeding a single phase genset to my 3 phase house. Not sure if you remember that set up. Recently when I made the genset auto start I fed the pool/shed area from a pre-wired aircon feed that I never used, to keep the aquaponics/hydroponics going.

[Crossy]

Is the pool remote from the house??