Iso Ground

hillbilly1 said:
I’ve ran into many isolated ground systems that were truly “isolated” no ground connection at all on the isolated ground bar. LOL!
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I've posted this before but how's this one? This was the IG conductor that ran from the panel's isolated ground bar to a piece of rebar in the concrete deck above the panel.1000000521.jpg
 
The idea of IG circuits is to prevent leakage, ground and lost Neutral currents from other circuits, using the IG circuits Signal, Data & Control cables as alternate paths back back to the Main Neutral point.
 
If I were to wire an IG circuit (No I'm not planning on doing so).

a) run all the IG receptacles to a central point junction box.
Trying to keep each run as short as reasonable.

b) then a single Hot, Neutral & IG-EGC back to the main panel.

c) let the EMT take care of grounding the boxes.
 
Speedskater said:
If I were to wire an IG circuit (No I'm not planning on doing so).

a) run all the IG receptacles to a central point junction box.
Trying to keep each run as short as reasonable.

b) then a single Hot, Neutral & IG-EGC back to the main panel.

c) let the EMT take care of grounding the boxes.
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That’s the way it’s supposed to be.
 
hillbilly1 said:
It was done in the early days of locknut worshipers, where a loose locknut or coupling would cause noise. Now a ground is pulled in almost every thing not relying on the integrity of the metal conduit system, so it is no longer needed.
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What about the integrity of all the wirenut connections? I see far more questionable wirenut connections than box connector or coupling connections.
 
electrofelon said:
I still dont follow that reasoning. IF you or your people are doing the pipe work, you should be assuring its quality. Doing proper quality pipe work is important regardless of if there is a wire EGC or not. Are people saying, "my pipe work is garbage so Im going to pull a wire EGC"?
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Same with wire nuts. Are your people doing crap work on wire nuts?
 
hillbilly1 said:
That’s the way it’s supposed to be.
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Yep, but I have read about:

a) Running each receptacle on it's own cable all the way back to the main panel.
b) running the IG-EGC wire on a different path than the Hot & Neutral.
c) using IG receptacles in NM-B circuits.
d) running the IG-EGC to a isolated ground rod.
 
Speedskater said:
Yep, but I have read about:

a) Running each receptacle on it's own cable all the way back to the main panel.
b) running the IG_EGC wire on a different path than the Hot & Neutral.
c) using IG receptacles in NM-B circuits.
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B is not permitted.

C works if you have NM cable, a plastic box, IG receptacle and a direct run back to the service.
 
electrofelon said:
Of course not. The discussion is about pulling a wire EGC BECAUSE the pipe work is apparently done poorly and isnt a good EGC. I am just trying to understand: If you do the pipe work and are pulling a wire EGC, you must not trust your pipe work.
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Seen too many times where after the install, another trade (usually sheet rockers) knock the boxes around on the studs, causing the locknut to loosen, fork lifts or other equipment damaging the pipe. One case in point, a big box store had a rack become energized because a pipe was pulled loose, and the hot cut into the pipe on the disconnected end. The breaker did not trip because the egc was the pipe. If a wire egc had been used, the breaker would have tripped. Luckily the customers were only getting a mild shock. But even though the rack was bolted to a concrete floor, it was not a low enough resistance to trip the breaker.
 
Continuing:

a) Running each receptacle on it's own cable all the way back to the main panel.
Sometimes making each wire run exactly the same length.

b) running the IG-EGC wire on a different path than the Hot & Neutral.
Being not permitted, doesn't mean it doesn't happen!

c) using IG receptacles in NM-B circuits.
If it's NM_B cable and plastic boxes, there is no need for IG receptacles.
 
Speedskater said:
c) using IG receptacles in NM-B circuits.
If it's NM_B cable and plastic boxes, there is no need for IG receptacles.
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True but it would still indicate that the circuit is designed and installed as an IG circuit. If someone is paying for an IG circuit they would get what they're paying for. You're correct that the combination of the plastic box and a standard receptacle would accomplish the same thing.
 
hillbilly1 said:
Seen too many times where after the install, another trade (usually sheet rockers) knock the boxes around on the studs, causing the locknut to loosen, fork lifts or other equipment damaging the pipe. One case in point, a big box store had a rack become energized because a pipe was pulled loose, and the hot cut into the pipe on the disconnected end. The breaker did not trip because the egc was the pipe. If a wire egc had been used, the breaker would have tripped. Luckily the customers were only getting a mild shock. But even though the rack was bolted to a concrete floor, it was not a low enough resistance to trip the breaker.
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Many times, which probably includes your example, the problem isnt a lack of a wire EGC, its the wrong wiring method, poor choice of routing, or poor maintenance.

And yes there are absolutely times when perhaps running a wire EGC is prudent. What drives me crazy is generalizing without any critical thinking that a wire EGC should always be installed. A single 3/4 pipe run on a non-conductive surface like plywood or drywall and not struted up with other conduits: sure maybe a wire EGC is a good idea there. 10 2-in EMT on a strut rack attached to building steel: a wire EGC is retarded and a complete waste.
 
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