Isolation transformer in place of a GFCI

[captainvi...@gmail.com]

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

[John Robertson]

On 2018/03/11 7:41 PM, captainvi...@gmail.com 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.

If you grabbed each side of the secondary you would receive a
100/115/120/220/240VAC shock (depending on where you live on Earth). If
somehow one side of the secondary connected to earth ground then you
would back to the same risk of electrical shock. Your decision to run
GFCI is correct IMHO.

>
> 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
>

Best decision.

John :-#)#

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[Mike Coon]

In article <Ao6dnUV3-ZCObjjH...@giganews.com>,
sp...@flippers.com says...

>
> If you grabbed each side of the secondary you would receive a
> 100/115/120/220/240VAC shock (depending on where you live on Earth). If
> somehow one side of the secondary connected to earth ground then you
> would back to the same risk of electrical shock. Your decision to run
> GFCI is correct IMHO.

I would prefer "either" rather than "each". Certainly not "both"! We
have road signs saying "Use both lanes" which appear to encourage
straddling. Presumably the public are supposed not to understand
"either"...

Mike.

[peterw...@gmail.com]

An isolation transformer does not guard against electrocution if one inserts one's self into the circuit. All it does is isolate the primary from the secondary such that for that circuit, the secondary side is isolated from ground. A GFCI device is the _only_ valid choice in this situation.

Peter Wieck
Melrose Park, PA

[Terry Schwartz]

Disagree. A much better choice is to remove the lighting and replace with a low voltage string, or a solar/battery powered string, or eliminate it all together.

By low voltage, I don't mean a modern string of LED lights. I mean a transformer isolated 12v system. The transformer should still be on a GFCI circuit.

120V above the pool area is just foolish and dangerous.

The pool pump motor may not like being on a GFCI. Often, inductive motor loads will trip them under a heavy load such as startup or near stall. In that case, the GFCI will work better back at the load center (circuit breaker panel) where the inductance of the wiring does not compound the problem. I just dealt with this last summer on a boat lift circuit.

Terry

[peterw...@gmail.com]

On Monday, March 12, 2018 at 9:41:38 AM UTC-4, Terry Schwartz wrote:

> Disagree. A much better choice is to remove the lighting and replace with a low voltage string, or a solar/battery powered string, or eliminate it all together.
>
> By low voltage, I don't mean a modern string of LED lights. I mean a transformer isolated 12v system. The transformer should still be on a GFCI circuit.
>
> 120V above the pool area is just foolish and dangerous.
>
> The pool pump motor may not like being on a GFCI. Often, inductive motor loads will trip them under a heavy load such as startup or near stall. In that case, the GFCI will work better back at the load center (circuit breaker panel) where the inductance of the wiring does not compound the problem. I just dealt with this last summer on a boat lift circuit.
>
> Terry

Of course. But if 120 VAC must be used, a GFCI devices is the only valid choice.

We feed our hot-tubs from a 50A GFCI safety switch in a dry location away from the hot-tub, but not near the main panel. It is easily reached from the outside as well.

[Ralph Mowery]

In article <a4bd1a14-82de-42bb...@googlegroups.com>,
captainvi...@gmail.com says...

An isolation transformer would be safe up to a point. If there is a
breakdown in the insulation anywhere in the circuit, one side of the
circuit becomes grounded by accident and no one notices it. Then if
someone gets on the other side of the line, he is shocked or worse.
That is one reason most circuits are grounded.

[John Robertson]

Further to this, one can purchase GFCI plugs that replace the original
power cord plug and provide the same safety aspects as a GFCI outlet or
circuit breaker. The advantage is you can add that to the power cord
quickly...

https://store.leviton.com/collections/gfci/products/right-angle-automatic-reset-user-attachable-gfci-plug-15a-125v-16693?variant=18216174467

Do get one that is not counterfeit - Amazon/eBay are not reliable
sources as the dealers there are completely unregulated and will sell
you fakes as easily as real items. Go to a bricks and mortar shop if you
want proper electrical safety.

[tabb...@gmail.com]

On Monday, 12 March 2018 02:41:15 UTC, captainvi...@gmail.com 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

[Rheilly Phoull]

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

[gregz]

Depends on isolation transformer type too. Some ground secondaries for
noise.

Greg

[mako...@yahoo.com]

I can't see how the motor could fail and become a shock hazard so
> > I was more concerned about the lights.
>

be sure the motor frame and all metal pipes are well grounded.

m

[captainvi...@gmail.com]

On Sunday, March 11, 2018 at 10:41:15 PM UTC-4, captainvi...@gmail.com 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

I've heard about how the inductive spark at the run start switch on some of these motors can cause GFCI's to randomly trip out and sometimes they are even destroyed by this. And I know also that with this guy if it starts to become a constant problem the GFCI will simply be replaced with a standard duplex receptacle. So I have to ask if on the off hand chance the motor wiring shorts to ground, and if the motor frame is properly grounded in theory there would be no chance that anyone in the pool would be affected by this....right? Lenny

[Ralph Mowery]

In article <640b27de-50ea-4488...@googlegroups.com>,
captainvi...@gmail.com says...

>
> I've heard about how the inductive spark at the run start switch on some of these motors can cause GFCI's to randomly trip out and sometimes they are even destroyed by this. And I know also that with this guy if it starts to become a constant problem the GFCI will simply be replaced with a standard duplex receptacle. So I have
to ask if on the off hand chance the motor wiring shorts to ground, and if the motor frame is properly grounded in theory there would be no chance that anyone in the pool would be affected by this....right? Lenny
>
>

The words Theory and Proper are correct, but sometimes the proper
becomes undone and the theory goes out the window.

[Fox's Mercantile]

You're already screwed. You looked at it.
Anything that happens now is your fault.

The only recourse you have now is to fix it correctly.
And that means no stupid shit with an isolation transformer
or any other "white trash" repair ideas you come up with.

Fix it properly, make sure EVERYTHING is bonded to grond
properly and install a GFCI.

The alternative is to do nothing then make explanations
after somebody's kid gets killed.



--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[jurb...@gmail.com]

>"You're already screwed. You looked at it. '

You got that right. People think we have some eye power like Superman or something.

Actually an isolation transformer would work, but there is nothing to indicate an insidious fault. All it takes is enough static electricity like during a thunderstorm striking nearby or something and it no longer isolates.

So it would be wise to use a GFCI, and then of course you don't need the isolation transformer.

Circuit breakers and GFCI outlets are designed to minimize the possibility of a no trip failure mode. No such thing in an isolation transformer. It could make it worse actually.

I would still recommend a low voltage alternative for the lighting. And a GFCI because when you are all wet you can get a shock from 12 volts. Probably not lethal directly, but could prevent you from getting your head out of the water or something.

[tabb...@gmail.com]

GFCIs are far from failsafe. Well worth having but not entirely reliable by any means, and not failsafe.


NT

[Tim R]

On Tuesday, March 13, 2018 at 7:41:09 PM UTC-4, Fox's Mercantile wrote:
> You're already screwed. You looked at it.

Yup. At work we say, "you touch it, you own it."

[peterw...@gmail.com]

On Wednesday, March 14, 2018 at 1:44:28 AM UTC-4, tabb...@gmail.com wrote:

> GFCIs are far from failsafe. Well worth having but not entirely reliable by any means, and not failsafe.
>

Nothing is fail-safe other than a low-voltage, battery-operated system. Anything that includes a primary source whether isolated or not, whether on a GFCI device, or not - there could be a way for primary power to migrate to the secondary side and/or jump the GFCI device. One may reduce the odds of failure via redundancy, or by other means. Or, one may take ordinary common-sense precautions in the full understanding that nothing is perfect.

Kinda-sorta like spending one's life living under a rock, or taking the ordinary risks of daily life and enjoy what life one is allotted under such terrible threats.

[tabb...@gmail.com]

On Wednesday, 14 March 2018 20:04:04 UTC, pf...@aol.com wrote:

That doesn't really tell us anything does it. Let me put it another way: RCD failures are no rarity. They're nowhere near failsafe. And of course they don't act on all shock/electrocution scenarios anyway.


NT

[jurb...@gmail.com]

>"Nothing is fail-safe other than a low-voltage, battery-operated system."

Almost, such a system could develop line leakage like any other. Then it is dependent on the GFCI.

[Terry Schwartz]

On Wednesday, March 14, 2018 at 7:16:23 PM UTC-5, jurb...@gmail.com wrote:
> >"Nothing is fail-safe other than a low-voltage, battery-operated system."
>
> Almost, such a system could develop line leakage like any other. Then it is dependent on the GFCI.

A low voltage, battery-operated system can develop line leakage? How is that? And exactly where in a battery system would one use a GFCI?

[jurb...@gmail.com]

>"How is that?"

The charger.

Unless you mean solar, that is different.

Know what ? I think it would be adequate just to use a GFCI breaker AND a GFCI outlet and be done with it.

But seriously, did you mean that they disconnect the charger when the lights are in use ? If you meant that or solar then I was wrong.

[Terry Schwartz]

I envisioned an LED system with a healthy sized gel battery.... charging would take place when the system is disconnected. With the right battery you could probably run such a light string all summer and only need to charge it a few times. With a solar array, never.

Leaving a charger connected would defeat the purpose. And some chargers will only charge until the voltage level is met, and not restart unless disconnected anyway. A battery maintainer or tender would likely be smart enough to charge when the voltage drops. But it's a moot point.

One thing I can say with certainty here is that the 120V string of lights above the pool MUST GO!

[jurb...@gmail.com]

>"One thing I can say with certainty here is that the 120V string of lights above the pool MUST GO! "

I used to do electrical work. Changed out a box and subsequently they wanted me to bid on digging a ditch for power to the pool and garage because the wires were overhead at the time. I had to turn it down because it was just too much PITA. If they had called on me before the pool was in it might have been different but people do not think ahead. The job was bad enough, had to make a new hole for the mains, and it was right in the corner so had to cut the cover side off an inch or so. I hope they got it done. Thinking about it, if one of the wires, even the hot fell into the pool they would be alright until they tried to step out of it. If there was a load and both ends fell in, ZZZAAAPPP. If both wires fell in from the fed side also ZZZAAAPPP.

[Tim R]

On Thursday, March 15, 2018 at 12:34:00 PM UTC-4, Terry Schwartz wrote:
> I envisioned an LED system with a healthy sized gel battery.... charging would take place when the system is disconnected. With the right battery you could probably run such a light string all summer and only need to charge it a few times. With a solar array, never.
>

Of course solar power doesn't work at night, and you don't need lights during the day.

(the moon is much more important than the sun. It gives us light at night, when we actually need it.)

[Terry Schwartz]

Of course, the solar cells would charge a battery......