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Re: IG receptacles [Re: George Little] #199906 03/14/11 07:51 AM
Joined: Feb 2011
Posts: 56
P
pooL8 Offline
Member
Canadian Code is pretty clear...

10-906
(7)In the case of metallically enclosed systems where the grounding path is provided by the metal enclosure,
a bonding jumper shall be installed to bond the grounding terminal of the receptacle to the enclosure.

(8) Notwithstanding Subrules (6) and (7), the bonding jumper, in the case of receptacles having grounding
terminals isolated from the mounting strap required for special equipment, shall be permitted to be
extended directly back to the distribution panel.


2017 / 2014 NEC & Related Books and Study Guides
Re: IG receptacles [Re: George Little] #199922 03/14/11 02:54 PM
Joined: Jul 2004
Posts: 9,604
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gfretwell Offline
Member
It still says "shall be permitted" not "shall extend to" wink


Greg Fretwell
Re: IG receptacles [Re: George Little] #199923 03/14/11 03:24 PM
Joined: Jan 2004
Posts: 1,507
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George Little Offline OP
Member
Greg- I'm starting to think that you aren't in favor of having a insulated and isolated grounding conductor run back to the source. I hope that's not why you are objecting to use of the concept. The fact remains if you see an orange triangle on a receptacle don't you expect that the installer has run a insulated grounding conductor back to the source- because if he didn't he/she has defeated any benefit that might be there with an IG circuit. One can dispute the benefit for sure and I have my doubts on the benefit or need for such an installation. You've had more experience than I have because of your exposure to the computer facet of our industry. Maybe the benefit is dubious at best but the circuit should be installed as having a clean ground based on the orange triangle. That's, as they say "My Final Answer".


George Little
Re: IG receptacles [Re: George Little] #199925 03/14/11 03:35 PM
Joined: Jul 2004
Posts: 9,604
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gfretwell Offline
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I am just saying the code does not define "isolated ground" nor does it have any "shall do" language.
Everything is just permissive language allowing you to avoid normal practice if you want to.


Greg Fretwell
Re: IG receptacles [Re: George Little] #199929 03/14/11 05:33 PM
Joined: Apr 2002
Posts: 7,251
HotLine1 Online Content
Member
George:

Just a quick FYI, from the 2011 NEC changes.....
517.16 revision IG receptacles are no longer permitted.

517.13 (B) was revised also.



John
Re: IG receptacles [Re: gfretwell] #199947 03/15/11 07:04 AM
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pooL8 Offline
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AHHHHH

So I 'shall be allowed'.... (but I shall not have to).

Isolated from as many mechanical connections as possible, is about as 'isolated' as a ground CAN be, until it fails. Cause ground is ground, until it isn't.

That's why I said 'pretty clear', and not 'clear' smile

Since I'm 'allowed' to now..... I think it would be better to use a standard receptacle and a separate physical bond wire extended back to the panel. This would ensure that if there was a mechanical ground failure (emt come loose etc), the separate bond wire would become the least resistive path to ground.
With an isolated ground receptacle and a failed mechanical ground, the potential differece imposed between the now open ground on the yoke, and the solid grounded bond wire, could be more harmful to equipment.

I can't find Isolated ground anywhere else in the code but what I posted.... and that language (once pointed out to me) is pretty obvious.

Re: IG receptacles [Re: George Little] #199949 03/15/11 09:42 AM
Joined: Apr 2002
Posts: 7,251
HotLine1 Online Content
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Pool:
Be careful here...what you read within the debate with George, Greg, Luckyshadow, & myself is based on NEC! And our interpertations, which you can see differ. We are NOT referencing the CEC!


John
Re: IG receptacles [Re: George Little] #199957 03/15/11 01:43 PM
Joined: Jul 2004
Posts: 9,604
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gfretwell Offline
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The IG rule in 250.146(D) is simply permission not to follow the general practice of bonding the EGC every time you get a chance. It does not relieve the requirement that you have an effective bonding path back to the main bonding jumper but it allows you do do this with a home run of insulated wire, not landing anywhere in between but I see nothing that prevents you from landing that wire at any convenient bonding point along the way.
Would you fail this if the IG landed on the EGC bar in the load side distribution panel? (a common thing in computer room wiring where the "star ground topology" starts at the sub panel feeding the data center.


Greg Fretwell
Re: IG receptacles [Re: George Little] #199961 03/15/11 08:32 PM
Joined: Jan 2004
Posts: 1,507
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George Little Offline OP
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And yet one more reason to not hang on every word MH says. I am aware that the NEC does not specify how to terminate an IG grounding terminal, after all it's not a design manual. We were told that from the start. But if you see a orange triangle on a receptacle, you don't expect conventional grounding, at least I don't. So what's so special about having an insulated jumper from the grounding terminal on an IG to the box it's installed in? The 6" long jumpers that we've used for years did that. So whether one believes in the IG concept or not the issue become what the design professional specifies on the plan. I'm betting on an insulated wire back to the source just like our Canadian brothers have it in their code.

Last edited by George Little; 03/15/11 08:42 PM. Reason: Added thought.

George Little
Re: IG receptacles [Re: HotLine1] #199962 03/15/11 09:24 PM
Joined: Feb 2011
Posts: 56
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pooL8 Offline
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Gotcha.
I'm a sucker for debate... and I ain't into learning how to find my way through a different maze smile
Though I'm sure they are very similar.


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