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#34497 - 02/13/04 05:16 AM Ground Rod for hot tub??
Rob Offline
Member
Registered: 12/22/03
Posts: 15
Loc: New York
Outdoor hot tub on a deck.
It is a replacement tub, I was
asked to wire it in. The original wiring
has a "bond" wire from the pump frame to a
ground rod under the deck. The panel box is located on other end of house. There is
a continuous ground to the main panel and a
2 pole GFCI breaker. (Is this in the NEC ? )
I am not sure I should rewire the new one to it again. Thanks for any info.
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#34498 - 02/13/04 10:50 AM Re: Ground Rod for hot tub??
earlydean Offline
Member
Registered: 12/22/03
Posts: 751
Loc: Griswold, CT, USA
In the 70s and 80s a lot of folks did not understand grounding. Many inspectors required them to and many electricians would install ground rods at all outdoor thingies (pools, hot tubs, light poles). We know better now, but you will still see it happening. Ignore it. Drive it out of sight. Just make sure you have a low impedance path back to the OC device, and all that should be bonded is.

Earl
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Earl
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#34499 - 02/13/04 09:07 PM Re: Ground Rod for hot tub??
PCBelarge Offline
Member
Registered: 06/08/03
Posts: 681
Loc: Dobbs Ferry, NY, USA
As Earl has mentioned, there is bonding and grounding required for pools and hottubs, and it seems that a lot of people have trouble understanding the difference between bonding the hottub and grounding it.

Pierre
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Pierre Belarge
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#34500 - 02/14/04 05:06 AM Re: Ground Rod for hot tub??
winnie Offline
Member
Registered: 09/15/03
Posts: 649
Loc: boston, ma
I know that you don't need a ground rod in order to properly bond a piece of equipment to the building electrical system, that 'grounding' a piece of equipment without bonding it to the OCPD panel is both wrong and dangerous, and that once you have bonded back to the panel, you will have also 'grounded' the electrical equipment.

However, is there any reason _not_ to use this extra ground rod that happens to already be buried in the ground at the location? If this hot tub were in a separate out-building with a subpanel, I presume that the subpanel would _require_ grounding electrodes, connected to the equipment grounding conductor, but isolated from the neutral.

-Jon

[This message has been edited by winnie (edited 02-14-2004).]
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#34501 - 02/14/04 05:55 AM Re: Ground Rod for hot tub??
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
250.54 would allow the use of the "extra" ground rod and I can not think of any reason it would do more harm than good.

I also do not see what safety it will add so IMO using it is a waste of stock.

However if this outdoor hot tub has more than one circuit feeding it or is fed by a feeder you may be required by 250.32(A) to install and use a ground rod.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#34502 - 02/14/04 07:42 AM Re: Ground Rod for hot tub??
Active 1 Offline
Member
Registered: 02/22/03
Posts: 687
Loc: Grayslake IL, USA
To correctly utilize the hot tub ground rod would it not require a larger ground wire? Then to fit the larger wire a bigger pipe.

Example:

A 50 Amp hot tub I would run a # 8 equipment ground to the first (outside) disconect. Then a # 10 from that disconect to the panel.

To use the ground rod by the tub on say a 200 a service it would require a # 4 the entire distance.

I don't know if there is something in the NEC but around here the branch circuits would never be run with the buildings grounding system.

What would happen to the branch circuits or hot tub in the same pipe as the grounding system if it took a surge from lighting? I think it could induce some voltage to the other circuits.
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#34503 - 02/14/04 07:55 AM Re: Ground Rod for hot tub??
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Hi Active as this ground rod is considered a supplementary ground rod many of the regular requirements do not apply.

Quote:
250.54 Supplementary Grounding Electrodes.
Supplementary grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118 and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.56, but the earth shall not be used as the sole equipment grounding conductor.


In short if you choose to install this supplementary electrode you simply connect it to the EGC wherever you want with whatever size wire you want.

Unless there is local amendment I do not see how your inspectors could fail this.

Bob
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#34504 - 02/14/04 09:46 AM Re: Ground Rod for hot tub??
electure Offline


Member
Registered: 12/24/00
Posts: 4259
Loc: Fullerton, CA USA
The use of the words "supplemental" and "supplementary" might throw some off.
A supplemental electrode is one that's required by 250.53(D)(2) to augment an underground metallic water line at a service.
A required supplemental electrode still doesn't have to be connected with a conductor larger than a #6 See250.53(E).

A supplementary electrode is, as iwire says, just that. 250.54, and is permitted
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#34505 - 02/14/04 06:35 PM Re: Ground Rod for hot tub??
Active 1 Offline
Member
Registered: 02/22/03
Posts: 687
Loc: Grayslake IL, USA
Thanks Iwire and electure. I did forget you could use a #6 for the rod. I tend to just use the extra from the water pipe run because the rod is never too far.
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#34506 - 02/15/04 04:20 AM Re: Ground Rod for hot tub??
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Quote:
The use of the words "supplemental" and "supplementary" might throw some off.


Why would that be confusing.

Thanks Scott that is a very good point, the "supplemental" rod is subject to the rules of other electrodes.

Bob
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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