Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old March 13th 18, 08:44 AM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

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


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

Greg

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Old March 13th 18, 02:11 PM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

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
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Old March 13th 18, 08:01 PM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

On Sunday, March 11, 2018 at 10:41:15 PM UTC-4, 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
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Old March 13th 18, 11:41 PM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

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 **** 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


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Old March 14th 18, 12:35 AM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

"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.
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Old March 14th 18, 05:44 AM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

On Wednesday, 14 March 2018 00:35:14 UTC, wrote:
"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.


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


NT
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Old March 14th 18, 12:29 PM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

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."
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Old March 14th 18, 08:04 PM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

On Wednesday, March 14, 2018 at 1:44:28 AM UTC-4, 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.

Peter Wieck
Melrose Park, PA
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Old March 14th 18, 08:50 PM posted to sci.electronics.repair
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Default Isolation transformer in place of a GFCI

On Wednesday, 14 March 2018 20:04:04 UTC, wrote:
On Wednesday, March 14, 2018 at 1:44:28 AM UTC-4, tabby 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.

Peter Wieck
Melrose Park, PA


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


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