Using a 3/C with ground cable and bonding bushings on conduit

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WarrMann said:
Path of least resistance is also the shortest path. For example - we cannot just tap one set of conductors from a parallel service

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Path of least resistance is a cute statement, but it is a misnomer. Current will take all paths, it will merely be proportional to the resistance.
 
Strathead said:
Path of least resistance is a cute statement, but it is a misnomer. Current will take all paths, it will merely be proportional to the resistance.
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You are right, however smart assedly you decided to put it. And considering you're just repeating a previous post...

And i am aware that current finds all paths. That's a reason why we don't bond ground and neutral after the disconnect.

However this response was meant specifically about this OPs situation if you read my previous posts. My point in using a parallel feed as an example was that the current that will physically trip the OPs breaker will mostly be going through the cables EGC (path of least resistance will produce the larger current a short, no?) in the question he asked. Not through his poorly bonded conduit, which will just get toasty.

Your point is taken though. This forum relies on the written word, and a technical one at that. I should make a better effort to clarify my points.

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WarrMann said:
will mostly be going through the cables EGC (path of least resistance will produce the larger current a short, no?)
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If the cable is inside the conduit, and, a phase conductor should happen to short to the conduit, the fault current will mostly be returning through the conduit, not the EGC that is integral to the cable.

Thus the need to insure proper bonding for a low impedance return path of the raceway itself.

JAP>
 
jap said:
If the cable is inside the conduit, and, a phase conductor should happen to short to the conduit, the fault current will mostly be returning through the conduit, not the EGC that is integral to the cable.
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Again... this was part of a response to a question about the conductors shorting to the cables ground, not the conduit.

jap said:
Thus the need to insure proper bonding for a low impedance return path of the raceway itself.

JAP>
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Couldn't agree more




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turtlepokerman said:
Greetings,

I'm going a little crazy here with the "equipment ground" versus a "bonding ground". What I currently have is a feeder cable that goes from a 70A - 480V feeder breaker to a 100A Disconnect switch. The cable is a 3/C #4 w/ gnd cable routed through aluminum emt conduit. The inspector on site says that I need bonding bushings on both ends of the conduit to maintain electrical continuity between the panels and the disconnect switch. The current conduit fittings are not UL listed as a grounding means.

Why would I need the conduit bushing on both ends of the raceway if I run a ground conductor in the cable? If a fault occurs in the raceway, the fault current would go through the equipment ground in the cable. Am I missing something?

Any help is appreciated.
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I'm curious, if you are you are using a raceway system for this circuit, why are you are using a cable and not single conductors?
 
WarrMann said:
You are right, however smart assedly you decided to put it. And considering you're just repeating a previous post...

And i am aware that current finds all paths. That's a reason why we don't bond ground and neutral after the disconnect.

However this response was meant specifically about this OPs situation if you read my previous posts. My point in using a parallel feed as an example was that the current that will physically trip the OPs breaker will mostly be going through the cables EGC (path of least resistance will produce the larger current a short, no?) in the question he asked. Not through his poorly bonded conduit, which will just get toasty.

Your point is taken though. This forum relies on the written word, and a technical one at that. I should make a better effort to clarify my points.

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Click to expand...

it wasn't meant to be sarcastic. Sorry that it came across that way.
 
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