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Ground Rod for hot tub?? #34497 02/13/04 09:16 AM
Joined: Dec 2003
Posts: 15
R
Rob Offline OP
Member
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.

Work Gear for Electricians and the Trades
Re: Ground Rod for hot tub?? #34498 02/13/04 02:50 PM
Joined: Dec 2003
Posts: 751
E
earlydean Offline
Member
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


Earl
Re: Ground Rod for hot tub?? #34499 02/14/04 01:07 AM
Joined: Jun 2003
Posts: 681
P
PCBelarge Offline
Member
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


Pierre Belarge
Re: Ground Rod for hot tub?? #34500 02/14/04 09:06 AM
Joined: Sep 2003
Posts: 649
W
winnie Offline
Member
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).]

Re: Ground Rod for hot tub?? #34501 02/14/04 09:55 AM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
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. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Ground Rod for hot tub?? #34502 02/14/04 11:42 AM
Joined: Feb 2003
Posts: 687
A
Active 1 Offline
Member
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.

Re: Ground Rod for hot tub?? #34503 02/14/04 11:55 AM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
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


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Ground Rod for hot tub?? #34504 02/14/04 01:46 PM
Joined: Dec 2000
Posts: 4,283
electure Offline
Member
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

Re: Ground Rod for hot tub?? #34505 02/14/04 10:35 PM
Joined: Feb 2003
Posts: 687
A
Active 1 Offline
Member
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.

Re: Ground Rod for hot tub?? #34506 02/15/04 08:20 AM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
Quote
The use of the words "supplemental" and "supplementary" might throw some off.

Why would that be confusing. [Linked Image]

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

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

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