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Rheilly Phoull[_2_]

On 13/03/2018 12:19 AM, wrote:

On Monday, 12 March 2018 02:41:15 UTC, wrote:

A friend of mine has a 120volt string of lights above his swimming pool. There is one 15 amp circuit for both the lighting and the pump motor circuit. This circuit is not protected by a GFCI outlet. The lights however are high enough so that no one can ever reach up and grab them while in the pool. We have had discussions about installing a GFCI on the pool circuit but as of the end of last Summer's swimming season it had not been done. One day last Summer I observed his kids in the pool shooting water blaster pistols in the air. Alarmed I quickly killed power to the lights. Naturally my concern was that someone in the pool shooting water up at the lights could be electrocuted. This brought about an interesting hypothetical discussion. What if the pool lighting circuit were connected through an isolation transformer. In theory then you should be able to grab each side of the secondary without being shocked right? I can't see how the motor could fail and become a shock hazard so I was more concerned about the lights.

In any event I'm going to install a GFCI on his pool circuit for him before the start of swimming season which will be coming up in a couple of months. Thanks, Lenny

The only sensible option is to remove them and fit LV lights if wished. But to explore the hypothetical - or in your case real situation:
1. I am far from the only person to have been shocked by touching one terminal of an iso transformer. They aren't always set up to isolate, and there is interwinding capacitance too. And of course there are faulty transformers.
2. In an ideal world, an iso protects against contact with one terminal. It offers no protection whatever against contact with 2.
3. 120v lights can fall into the water
4. RCDs/GFCIs & isos interact to some extent in that if you put the RCD before the iso, the output is NOT RCD protected at all. If used together the RCd must go after the iso.
6. Rain-like water drops don't conduct electricity downward. You can stand under HV lines in the rain, the gaps between drops keep you safe. But this does NOT occur if you fire a water pistol up at it.
5. Remove the lights now. People in bodies of water are extremely vulnerable to shock.

NT

Yeah, mains voltages around pools are waiting for the above average
idiot that no one can protect.