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#129511 - 04/05/05 01:55 PM grounding
Roxie Offline
Junior Member

Registered: 04/05/05
Posts: 7
Hi all, would like your take and in put on this.
ground wire from panel to grd rod to second grd rod back to panel for a loop.

isn't this just creating a path or circle for lighting to follow, wouldn't it be better to terminate the wire at the last grd rod.
dosen't the grounding actually start and end at the clamp in the panel before it gets to the grd bar?

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#129512 - 04/13/05 05:02 AM Re: grounding
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
I think the two points that would be put forward in favor of this approach are:

1. Reduced resistance due to the parallel path.

2. One bad connection will still leave a good ground via the other side of the loop.

I know the NEC has limitations on paralleled conductors, but I'm guessing that this would not apply to grounding electrode conductors as they are not designed to carry current under normal operation. (And there are already plenty of parallel paths due to all the bonding anyway.)

Maybe our code experts can confirm?

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#129513 - 04/16/05 06:08 AM Re: grounding
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Roxie,
I'm with Paul on this one.
2 wires to 2 rods with a wire in between would make an ideal ground for lightning.
As with any electricity, it would take the quickest (and simplest) path to Earth, the chances of it coming back up one of the other wires is quite remote, however, I would advise that the 2 wires be terminated close together in the Ground Bar.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#129514 - 04/16/05 03:25 PM Re: grounding
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
May I make the point that for any ground (earth) rod or rods, the resistance is in the ground itself, not the rod. So, if two rods are driven too close to each other, in theory at least, the net resistance will not be simply halved. When separated by 12", two driven rods are likely, depending on the soil's electrical properties, to be about 70% the resistance of one rod. If driven 4 feet apart, resistance may fall to perhaps 60% of a single rod- all wired in parallel, of course. This is probably reflected in Codes.
Alan
PS. Pauluk
Went to Mayenne Hospital earlier this evening for a routine heart scan 'ECG'. (Strong as an ox still, got a fuss-pot lady Doctor). Result- still A1, but when they started wiring me up with all those pads, suckers and clamps, all I kept thinking about was that bloody awful Florida Electric Chair stuff you posted in GD forum, you rotten sod!!! Cholesterol was very low too- so went to MacDonalds to top-up- you can't be too carefull!
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#129515 - 04/24/05 02:17 PM Re: grounding
Larry Fine Offline
Member

Registered: 02/18/05
Posts: 684
Loc: Richmond, VA
Interestingly enough, I just finished roughing a large house with two 200-amp disconnects feeding a pair of remotely-mounted main-lug panels. I ran the #6 solid copper from one rod, into the first disconnect, back out and into the second disconnect, and then out to the second rod.

As the wire was unbroken from rod to rod, each disconnect had two paths to ground, via two rods. The inspector said it was quite unorthodox, but it satisfied him and met the intention and letter of the requirements.

By the way, code requires the two rods to be at least six feet apart.

[This message has been edited by Larry Fine (edited 04-24-2005).]
_________________________
Larry Fine
Fine Electric Co.
fineelectricco.com

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