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.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old March 12th 18, 03:41 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jun 2012
Posts: 227
Default Isolation transformer in place of a GFCI

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

  #2   Report Post  
Old March 12th 18, 04:25 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jul 2006
Posts: 678
Default Isolation transformer in place of a GFCI

On 2018/03/11 7:41 PM, 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 :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
  #4   Report Post  
Old March 12th 18, 01:48 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Mar 2007
Posts: 1,202
Default Isolation transformer in place of a GFCI

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
  #5   Report Post  
Old March 12th 18, 02:41 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Dec 2017
Posts: 115
Default Isolation transformer in place of a GFCI

On Monday, March 12, 2018 at 7:48:53 AM UTC-5, wrote:
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


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.


  #6   Report Post  
Old March 12th 18, 02:54 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Mar 2007
Posts: 1,202
Default Isolation transformer in place of a GFCI

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.
  #7   Report Post  
Old March 12th 18, 03:20 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jul 2006
Posts: 3,207
Default Isolation transformer in place of a GFCI

In article ,
says...

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


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.

  #8   Report Post  
Old March 12th 18, 04:48 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jul 2006
Posts: 678
Default Isolation transformer in place of a GFCI

On 2018/03/11 8:25 PM, John Robertson wrote:
On 2018/03/11 7:41 PM, 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 :-#)#


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/collection...nt=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.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
  #9   Report Post  
Old March 12th 18, 05:19 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jan 2015
Posts: 8,987
Default Isolation transformer in place of a GFCI

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
  #10   Report Post  
Old March 13th 18, 06:09 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: May 2008
Posts: 175
Default Isolation transformer in place of a GFCI

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.


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
RF Isolation Transformer [email protected] Electronics 1 April 29th 09 06:27 PM
Electrically isolating network hardware from dehumidifier: isolation transformer or line conditioner? [email protected] Electronics Repair 6 December 4th 05 04:08 PM
Testing Isolation Transformer Ken Weitzel Electronics Repair 3 July 30th 05 04:14 AM
newbie question on probing transformerless ac power supplies with an isolation transformer costab06 Electronics Repair 2 July 10th 05 12:09 AM
Test to determine if something is an isolation transformer? [email protected] Electronics Repair 3 March 1st 05 09:35 PM


All times are GMT +1. The time now is 03:32 AM.

Powered by vBulletin® Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"

 

Copyright © 2017