Wire type EGC in the NEC

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Thoughts on why when wire type EGC's became popular, why insulated EGC's become more popular than bare? I'm doing a project in Mexico and the on site electricians insist that bare is typical when installing wire type EGC's.
 
ron said:
Thoughts on why when wire type EGC's became popular, why insulated EGC's become more popular than bare? I'm doing a project in Mexico and the on site electricians insist that bare is typical when installing wire type EGC's.
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I would guess THHN pulls easier than bare EGCs. All the installs I saw in mexico, none used conduit. They just cut a trench in the floor, put some sand down, and ran the wires in the sand and then concreted over the trench when it was done.
 
tom baker said:
Mike Holt once said "the safest wiring system would be 2 wire with GFCI" An egc provides a path to ground for a shock.
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Right. In our automation lab, we use isolation transformers. Same principle.

Sent from my SM-A326U using Tapatalk
 
mbrooke said:
Most people do not place expansion joints on conduit as needed or correctly. Fitting can loosen. Conduit oxides. Conduit moves.

On the other hand a copper spliced EGC is no different than a phase or neutral splice. We know it holds up.
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Many issues with this. It would apply equally to copper or aluminum if true. First as a matter of fastener science google a “Junkers” machine used for testing the self loosening theory. It turns out self loosening can happen but only under extreme circumstances that are impossible with pipe fittings.

Second we need to consider electrical contact theory. With electrical contacts pressure in a bolted or threaded fitting first cracks the oxide coating exposing bare metal. A little bit of both sides of the joint mix, forming metal on metal cold welded contacts called alpha spots. Further increases in pressure increase the number of alpha spots and smear and enlarge existing ones.

Oxide is along the edges, far removed from the joint. Alpha spots are the last to be consumed. Plus metal oxides are the basis for Schottky diodes and surge arresters…hardly the stuff of an insulator. Try Meggering rusty steel. It is almost as good as bare.

Conduit moves but so does electrical cables and everything else. It has little to do with an argument against conduits of trays as grounds,
 
Mbrooke, the question was asked and not answered, how much experience do you have installing EMT?
 
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paulengr said:
Many issues with this. It would apply equally to copper or aluminum if true. First as a matter of fastener science google a “Junkers” machine used for testing the self loosening theory. It turns out self loosening can happen but only under extreme circumstances that are impossible with pipe fittings.

Second we need to consider electrical contact theory. With electrical contacts pressure in a bolted or threaded fitting first cracks the oxide coating exposing bare metal. A little bit of both sides of the joint mix, forming metal on metal cold welded contacts called alpha spots. Further increases in pressure increase the number of alpha spots and smear and enlarge existing ones.

Oxide is along the edges, far removed from the joint. Alpha spots are the last to be consumed. Plus metal oxides are the basis for Schottky diodes and surge arresters…hardly the stuff of an insulator. Try Meggering rusty steel. It is almost as good as bare.

Conduit moves but so does electrical cables and everything else. It has little to do with an argument against conduits of trays as grounds,
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Wire has slack in conduit and j-boxes to move. Conduit on the other hand breaks a cold weld everytime it moves in the coupling, whereby the set screw and other contact points are moved to an oxide layer.

R matters, by far.
 
roger said:
You spend most of your life playing on the web, you know where MH contact information is or how to find it, quit playing games.

Roger
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:rolleyes:

I know Mike's Site, no guarantee I'll find it however. I'll look, no concern about that. Typically I just link to an address, PDF, screen shot or email when someone asks for it.
 
This is why I ask, no email listed for Brain House:


Not trying to be a hard head, just I have a reason for everything that I do even if it doesn't make sense or seem redundant on the surface.

But going back to EGCs I am willing to dispute that claim. EGCs does not increase shock risk MV excluded.
 
tom baker said:
????
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For as much attention to detail that is usually presented here, not just "for arguments sake", it's obvious when somebody is dodging a question. I'm a newbie and an outsider so I tend to just sit back and watch, but this one has me laughing. It's very clear there are many experts here and most stick to the point of this forum, NEC code references. It's the reason I found this forum, and more than any other resource this has helped me understand and digest this technical subject matter. It's also clear when people just want to argue over opinions, I'm getting the sense that some of the experienced members are "over it."

I appreciate all of the technical experience shared here. The occasional entertainment is a bonus. Thanks for sharing!
 
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