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Thread: EGC question

  1. #1
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    Default EGC question

    EGC, equipment grounding conductor cable coated with spray on Styrofoam.
    Is the considered acceptable?

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    Last edited by ROBERT YOUNG; 12-29-2016 at 12:14 PM.
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    Default Re: EGC question

    Quote Originally Posted by ROBERT YOUNG View Post
    EGC, equipment grounding conductor table ...
    Not sure what you mean with the word "table" in there?

    ... coated with spray on Styrofoam.
    Things can be coated with many things as long as there is chemical compatibility, and the connection is still accessible to be seen (one needs to be able to make sure that the connection is good).

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    Default Re: EGC question

    An EGC is typically in the branch circuit wiring. A GEC could be run in the wall and covered by insulation.

    Which one are you asking about.?

    All answers based on unamended National Electrical codes.

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    Default Re: EGC question

    EGC = equipment grounding conductor? And I think 'table' should be cable?


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    Default Re: EGC question

    [QUOTE=Jerry Peck;270943]Not sure what you mean with the word "table" in there?

    Sorry. Cable.

    Quote Originally Posted by Jerry Peck View Post
    Things can be coated with many things as long as there is chemical compatibility, and the connection is still accessible to be seen (one needs to be able to make sure that the connection is good).
    That could not be achieved even with my smallest mirror.
    Thanks as always.

    - - - Updated - - -

    Quote Originally Posted by Raymond Wand View Post
    EGC = equipment grounding conductor? And I think 'table' should be cable?
    Bingo!Cable.

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    Default Re: EGC question

    Quote Originally Posted by Raymond Wand View Post
    EGC = equipment grounding conductor?
    Yes.........

    All answers based on unamended National Electrical codes.

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    Default Re: EGC question

    Quote Originally Posted by Jim Port View Post
    An EGC is typically in the branch circuit wiring. A GEC could be run in the wall and covered by insulation.

    Which one are you asking about.?
    GEC to the ground rod/.grounding electrode
    Thanks Jim.
    Both actually but you are correct to what I was referring to.
    Not paying attention.

    Sorry wireless connection is buggy.

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    Default Re: EGC question

    Quote Originally Posted by Jim Port View Post
    A GEC could be run in the wall and covered by insulation.
    But the connections at each end are required to be accessible.

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    Default Re: EGC question

    Quote Originally Posted by Jerry Peck View Post
    But the connections at each end are required to be accessible.
    Even when the rod is buried?


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    Default Re: EGC question

    Quote Originally Posted by Roy Lewis View Post
    Even when the rod is buried?
    If it is a mechanical clamp, yes.

    If it is exothermically (spelling) welded, then no.

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    Default Re: EGC question

    I believe that if you check NEC 250-68 (A), Exception 1 and 2 you will find that a number of conditions where the electrode end of a GEC does not need to be accessible exist. A driven rod is one of them.

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

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    Default Re: EGC question

    Quote Originally Posted by Bill Kriegh View Post
    I believe that if you check NEC 250-68 (A), Exception 1 and 2 you will find that a number of conditions where the electrode end of a GEC does not need to be accessible exist. A driven rod is one of them.
    Bill,

    Thank you, I stand corrected.

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    Default Re: EGC question

    Quote Originally Posted by Jerry Peck View Post
    Bill,

    Thank you, I stand corrected.


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    Default Re: EGC question

    I thought so.
    Quote Originally Posted by Bill Kriegh View Post
    I believe that if you check NEC 250-68 (A), Exception 1 and 2 you will find that a number of conditions where the electrode end of a GEC does not need to be accessible exist. A driven rod is one of them.



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    Default Re: EGC question

    Quote Originally Posted by ROBERT YOUNG View Post
    GEC to the ground rod/.grounding electrode
    Thanks Jim.
    Both actually but you are correct to what I was referring to.
    Not paying attention.

    Sorry wireless connection is buggy.
    I have not yet found any indication that a paint has been investigated for use with cable sheaths, not to mention conductor insulations. This leaves the question up in the air. Certainly John Cangemi, a long-time CMP etc member and more recently a double honorary member of IAEI, cautioned against the use, before retiring from UL. Whether expanding foam has been tested for this I don't know.


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    Default Re: EGC question

    Quote Originally Posted by david shapiro View Post
    Certainly John Cangemi, a long-time CMP etc member and more recently a double honorary member of IAEI, cautioned against the use, before retiring from UL. Whether expanding foam has been tested for this I don't know.
    John is an excellent guy and sharp.

    As I recall, expanding foam is compatible with the PVC sheath used on nonmetallic-sheathed cable, the issue was with not allowing the cable to ventilate its heat out because it was encapsulated in the foam.

    The NEC first addressed this, as I recall, with more than two multi-conductor NM cables going through wood top plates and encased in foam, as used for fireblocking.

    It was later expanded to cables encased in thermal insulation (wording and intent is from memory). And the use of the term thermal insulation included other thermal insulation (fiberglass) as it had the same effect of trapping the heat at the cable and not allowing the cables to ventilate the heat out.

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    Default Re: EGC question

    Quote Originally Posted by Jerry Peck View Post
    John is an excellent guy and sharp.

    As I recall, expanding foam is compatible with the PVC sheath used on nonmetallic-sheathed cable, the issue was with not allowing the cable to ventilate its heat out because it was encapsulated in the foam.

    The NEC first addressed this, as I recall, with more than two multi-conductor NM cables going through wood top plates and encased in foam, as used for fireblocking.

    It was later expanded to cables encased in thermal insulation (wording and intent is from memory). And the use of the term thermal insulation included other thermal insulation (fiberglass) as it had the same effect of trapping the heat at the cable and not allowing the cables to ventilate the heat out.
    Thank you, Jerry.

    If it has been investigated for compatibility with PVC products, that's only reasonable; I'm happy to learn it. The GEC does not normally require any insulation or covering at all, so one could argue that if it has insulation that is deteriorated by foam, so what? However, if Robert is also talking about EGCs, and they're not cabled with energized and grounded conductors, there may be another issue, worse than that of baking recent romex. The most common use of separate grounding conductors is with open and K/T wiring, and after this with NM that's old enough to have been manufactured without a ground. NEC 394.12(%) says K&T can't be encased in insulation; the expectation was that its environment would be akin to being strung in air, if not free air. Old NM isn't quite as bad, but it certainly had no more than a 60deg C temperature rating.


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    Default Re: EGC question

    Quote Originally Posted by david shapiro View Post
    Thank you, Jerry.

    If it has been investigated for compatibility with PVC products, that's only reasonable; I'm happy to learn it. The GEC does not normally require any insulation or covering at all, so one could argue that if it has insulation that is deteriorated by foam, so what? However, if Robert is also talking about EGCs, and they're not cabled with energized and grounded conductors, there may be another issue, worse than that of baking recent romex. The most common use of separate grounding conductors is with open and K/T wiring, and after this with NM that's old enough to have been manufactured without a ground. NEC 394.12(%) says K&T can't be encased in insulation; the expectation was that its environment would be akin to being strung in air, if not free air. Old NM isn't quite as bad, but it certainly had no more than a 60deg C temperature rating.
    Correct.

    And old NM (cloth covered) started out with rubber insulation, then went to thermoplastic, both were 60 degree C (at most, who knows what the rubber insulation was originally rated for or even if it had a temperature rating).

    Old-but newer NM with the PVC sheathing started out with no ground (i.e., 14-2 or 12-2) and the insulation was 60 degree C.

    It was not until NM-B came along, in the 1980s or early 1990s as I recall, did the conductor insulation go to 90 degree C, and the reason for that was not to address derating, the reason for that was because if 60 degree C insulation was installed in an attic, in most parts of the country (where the attic gets to even 115 degrees in the summer, and 115 is not that hot for attics) the derating would factor for ambient would have been 0.71, making 14 AWG derated to 10 amps ... just no one thought about it back then.

    (Note: revised the numbers below with edit, did the math wrong at first)

    Now, NM-B, 14-2 W/G, starts at 25 amps, derating for even that attic, with its higher derating factor of 0.89 (less derating) reduces the rating to 22.25 amp; and for a hot 140 degree attic with a derating factor of 0.77 to 19.25 amps, both still good for a 15 amp circuit.

    Any other derating, i.e., for lack of maintaining spacing issues derates from that derated ampacity.

    Last edited by Jerry Peck; 01-11-2017 at 04:12 PM. Reason: did the math wrong the first time
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