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#167426 - 08/12/07 09:17 AM Stray Voltage
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
Has anyone out there had or had any problem with stray voltage around pools. I am a working AHJ and I was a contractor for 15 years in my own business. I have seen stray voltage with fiberglass pools only so far. I realize that the 2005 NEC and the changes to sec. 680.26 try to resolve those problems. I was just wondering if anyone had problems with metal pools or the rebar type of inground pools.

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#167446 - 08/12/07 12:31 PM Re: Stray Voltage [Re: harold endean]
Alan Nadon Offline
Member

Registered: 03/10/05
Posts: 398
Loc: Elkhart, IN. USA
Several years ago a new in ground pool, rebar and vinyl liner, was causing a major confusion. The GFI receptacle at the pool would trip, with the circuit breaker for it in the off position. It would also trip when the wire to the breaker was disconnected. Only the ground and neutral were connected !
A house about 500 feet away had an open neutral and the pool was acting as a partial return path for their service.
This was with the older style GFI receptacles before they added the indicator lights.
It was a real head scratcher until it was tracked down.
Another installation was for a hot tub sitting on top of the ground about 8 feet from the UG service. The utilty company xformer in thee back yard had a loose neutral connection and people using the pool would get a tingle when they stepped out of the tub.
In both cases checking for open or poor neutral connections in the area of the pool located the cause.
I have heard that water flowing on some types on plastic will set up a static charge.
_________________________
Alan--
If it was easy, anyone could do it.

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#167449 - 08/12/07 12:51 PM Re: Stray Voltage [Re: Alan Nadon]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Harold:
A while back there was a 'stray' voltage situation making the local paper (Asbury Park Press) in Brick. Seems JCP&L/GPU use a 'single wire, earth return' distribution system, and something to do with the bare or undersized ground conductor at the poles. This is not my forte, so perhaps one of the 'line guys' here can enlarge on this theory.

Seems people with pools could have the main disco at the house 'off', and still record somewhere around 12-16 volts on the property.

This was a 'hot' subject for a while (in the paper), then it went away....

John
_________________________
John

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#167462 - 08/12/07 05:25 PM Re: Stray Voltage [Re: HotLine1]
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
John,

Yeah, I know of that story and I read a lot about it. ( I think it is still unresolved) I was just wondering if anyone else had problems with stray voltage with any kind of pools. As I said, I have seen stray voltage more than once with fiberglass pools, but not with metal or rebar pools.
BTW, did you hear that we are suppose to enforce a 3' band of bonding grid around hot tubs too? Even if the tubs were dropped on to existing patios?

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#167465 - 08/12/07 06:20 PM Re: Stray Voltage [Re: harold endean]
LK Offline

Member

Registered: 01/21/03
Posts: 1721
Loc: New Jersey
John,

Your not going to believe it, but they are still working on the stray problem, it appears the build out, was designed, back when that area was nothing but farms.

IMO, they need a lot of pole line work, with a upgraded return path.

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#167502 - 08/14/07 04:27 AM Re: Stray Voltage [Re: LK]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
LK:
I thought it was still hanging unresolved, but have not seen/heard anything. A few of the sites are within 1/2 mile of my home. Yes, JCP&L has a lot to do. They spent a lot of $$$ on the new additional feeders to the barrier island in the last few years and resolved that issue.

Harold:
Yes, hot tubs fall under 680.26 also. One solution other than the grid is an insulated 'base' under the tub. DCA was acceptable to that, alas only verbally as of now. Call me if you want any info

Stay safe
_________________________
John

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#167677 - 08/17/07 02:34 PM Re: Stray Voltage [Re: HotLine1]
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
John,

I heard all about rubber mats, pieces of wood, etc, to make the area non conducting. Now the DCA said that if you drop a 4'X4' tub on a 4'X4' pad, you don't need the bonding grid. (Is the earth conductive?) I had a gentleman put the tub on crushed stone. I guess the bond grid isn't needed there either. (I guess?)

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#167692 - 08/17/07 05:42 PM Re: Stray Voltage [Re: harold endean]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Harold:
I just received a lot of GOOD 680.26 info that supposed to be from Susan Borek. As soon as I confirm that she is OK with it, I'll get a copy to you.

Crushed stone and asphalt....are 'safe' based on the above text, but it's not odfficial yet. There also is a plastic solution for the hot tub...but it's $$$.
_________________________
John

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#167709 - 08/18/07 10:28 AM Re: Stray Voltage [Re: HotLine1]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
Capacitive coupling can generate nasty 'stray voltage' in UL listed hot tubs. It is essential that there be a true ground path from the exterior GFCI receptacle feeding such a tub.

Body salt accumulates in the hot tub making it increasingly conducting....

As installed, the hot water is pumped vigorously through motor field windings -- stray magnetic leakage is enough -- the pipes are plastic.

The end result is a "tank circuit" with a potential of over fifty volts from hot water to the wet surround. ( An actual situation; solved by running a 'bleeder' grounding conductor to the GEC by way of the all-copper cold water system.
_________________________
Tesla

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#167762 - 08/19/07 05:26 PM Re: Stray Voltage [Re: harold endean]
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
It seems to me that we had over 300 viewing of this post, yet no one has seem to have any problem with stray voltage around inground pools. I am just wondering if sec. 680.26 should even be in the NEC? I mean I can see why they bond the rebar and metal sides, but why did we need to extend the bonding grid 3' more around the pool? Just a comment, I am not angry or mad at anyone.

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