There's No Grounding Conductor in Disconnect Switch and Circuit Breaker Enclosure

ActionDave

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It's debatable. I'm considering to just put a note for contractor to verify ground continuity... Kinda feel iffy about using metal raceway as an ECG because , rarely see anybody do it, and I rarely see it.....
It's not debatable. There are thousands of miles of metal conduit in service as the sole EGC and it is performing fine. I bet you rarely see Multi Wire Branch Circuits as well.
 

Tainted

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New York
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Engineer
It's not debatable. There are thousands of miles of metal conduit in service as the sole EGC and it is performing fine. I bet you rarely see Multi Wire Branch Circuits as well.
lol, ok I will keep the feeders and conduit the way it is since I got a little bit of reassurance... you are correct I rarely see multi-wire branch circuits. I've seen some, usually requires the breakers to be interlocked. I guess there's the redundancy of not having neutrals shared?
 

DrSparks

Senior Member
Location
Madison, WI, USA
Reason we don't use EMT as EGC: unreliable continuity. Copper wire provides redundancy.

Reason we don't use MWBCs anymore: harmonic currents due to proliferation of switching power supplies.

Some people are just resistant to new ways. I'm sure when I'm an old timer I'll be the same way.

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ActionDave

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MWBC feel out of favor when the NEC added the simultaneous disconnect rule in '08. It was a major dumbing down of the electrical trade and one of the worst code changes ever just because a bunch of handymen or ill trained electricians didn't understand how to properly work on them. There was never a real world problem with harmonic currents on neutrals and there isn't now. All those old MWBC are still in service and powering up electronic lights, computers with switch mode power supplies without a problem.

And yes, most people are resistant to new way, but I'm not.
 

Tainted

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Location
New York
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Engineer
Question. Suppose a conductor will be used as an EGC, then does that mean if there’s a fault somewhere, the fault current will go to the EGC and the raceway at the same time? Wouldn’t that be parallel paths?
 

DrSparks

Senior Member
Location
Madison, WI, USA
Question. Suppose a conductor will be used as an ECG, then does that mean if there’s a fault somewhere, the fault current will go to the ECG and the raceway at the same time? Wouldn’t that be parallel paths?
Yes it would. The current would be inversely proportional to the impedance in each conductor.

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DrSparks

Senior Member
Location
Madison, WI, USA
MWBC feel out of favor when the NEC added the simultaneous disconnect rule in '08. It was a major dumbing down of the electrical trade and one of the worst code changes ever just because a bunch of handymen or ill trained electricians didn't understand how to properly work on them. There was never a real world problem with harmonic currents on neutrals and there isn't now. All those old MWBC are still in service and powering up electronic lights, computers with switch mode power supplies without a problem.

And yes, most people are resistant to new way, but I'm not.
All changes to best practices and the NEC are due to real world problems. Do you think engineers just sit down with a pen and paper and think of things to change our life? Everything has and always will be reactionary.

And many (well trained). Electricians have been seriously injured by MWBCs not on a common trip mechanism. Why fight things they improve safety? It's ridiculous my friend. What does a handle tie cost? My god.

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Tainted

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Location
New York
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Engineer
Sure, you could put it that way. The conductivity of 1 foot of 2" galvanized steel EMT is most certainly greater than a #8 copper wire.

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Wait… isn’t #8 too small for the 175A breaker? #8 is only up to 100A? Do you mean #6?
 

infinity

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Location
New Jersey
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Journeyman Electrician
It's debatable. I'm considering to just put a note for contractor to verify ground continuity... Kinda feel iffy about using metal raceway as an ECG because , rarely see anybody do it, and I rarely see it.

I think the pipe is 2" with THWN 3/0 feeders.
We do it all of the time up to 4" EMT. If the customer isn't paying for wire type EGC's they don't get one for free in the EMT. Personally I would stop worrying about it. If it passed inspection (meaning that it was installed in a code compliant manner) there is nothing else to be done.
 
I agree if it's wrench tight threaded rigid conduit. I don't consider EMT with setscrew connectors a viable EGC. Just from my own experience in years of factory work.

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Interesting. I have found the opposite, that a conduit system is a much more reliable EGC. I just don't trust the wire EGC to be made up correctly. All the time I see poor wire nut connections, improper and poor connections to enclosures, connections skipped because the box is mounted on concrete, etc.
 
I take it you disagree with that. Care to elaborate?

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I dont at all agree that changes in the NEC and the modern proclivity towards running wire EGC's are based on real world problems. Look at all the absurd crap in article 250 that has been there for half a century or more, most of the recent GFCI expansions, AFCI's, the surge protector requirement, no more MLO's, handle ties on MWBC's.....the list goes on. Pretty much no data or history of problems for this stuff.
 

Tainted

Senior Member
Location
New York
Occupation
Engineer
I dont at all agree that changes in the NEC and the modern proclivity towards running wire EGC's are based on real world problems. Look at all the absurd crap in article 250 that has been there for half a century or more, most of the recent GFCI expansions, AFCI's, the surge protector requirement, no more MLO's, handle ties on MWBC's.....the list goes on. Pretty much no data or history of problems for this stuff.
What are you referring to when mentioning ‘no more MLO?’ MLO panels are not allowed anymore?!
 
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