Conduit As Ground

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K_Mark

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I Was Asked The Question If Conduit Could Be Used As The Equipment Ground. We Ran Into A Situation Where A Control Panel Required 3 Phase, Plus A Neutral And A Ground. However, The Neutral Was Not Pulled And The Contractor Is Saying Thay Would Have To Pull All The Cables Out To Add The Neutral. What Was Pulled, Was 3-1/0 And A #6 Ground. So We Thought We Could Use The #6 As The Neutral For Some Lighting And Then Bond The Conduit On Either End. Any Suggestions? I Was Told The Code No Longer Allowed This Practice.
 
If the particular conduit type is listed as an EGC in 250.118 (it probably is) it is allowed.

Roger
 
You would also have to verify that the total neutral current would not exceed the ampacity of the #6 conductor. So if you haven?t yet performed a formal load calculation, now is the time.

Two more things: First, I agree that in order to pull one more conductor through the conduit, you would have to first remove the present conductors. Secondly, some local jurisdictions (I vaguely recall Chicago being one, but I might be wrong about that) specifically forbid the use of the conduit as the EGC, and require that a separate wire be pulled for this purpose.
 
I have a feeling that a #6 is too small for a feeder or circuit with 1/0 conductors. In any case, the #6 wire would have to have been white from the factory, and not re-colored.

I would suggest calculating the neutral current and using the #6 to pull in an appropriately-sized conductor. Charlie, I have done this on a 100'+ run with little difficulty.
 
LarryFine said:
I would suggest . . . using the #6 to pull in an appropriately-sized conductor.
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If you do that, you might as well pull another #6 to use as the EGC.

As to difficulty, that will depend on many factors, including the size of the conduit, the number and nature of bends, and the degree to which the run is "mostly straight." But it is not so much the difficulty of the pull, but rather the risk of damaging either the conductors already in the conduit or the ones you are pulling past them. If I were either the owner's representative or the project engineer, I would not allow it.
 
Thanks For Everyone's Input

Thanks For Everyone's Input

The #6 Is Actually Larger Than Needed. The Feeder Is Sized For 3 Motors And Several Lights. The Lights Will Be The Only Load The Neutral Will Have. The Conduit Is Suppose To Be Rmc, So According To 250.118 It Is Okay To Use The Conduit. I Appreciate Everyone's Input.
 
K_Mark said:
The #6 Is Actually Larger Than Needed. The Feeder Is Sized For 3 Motors And Several Lights. The Lights Will Be The Only Load The Neutral Will Have. The Conduit Is Suppose To Be Rmc, So According To 250.118 It Is Okay To Use The Conduit.
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I agree with the conduit as EGC. The wire color is the only issue. I'd vote for using it re-colored white, but the code requires #6 and smaller be white, not re-colored white.

Good luck.
 
LarryFine said:
The wire color is the only issue. I'd vote for using it re-colored white, but the code requires #6 and smaller be white, not re-colored white.

Good luck.
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Isn't that a crock. Why can you re-color larger than #6 but you can't when it is #6 or smaller. Anyone know why this is so.

I must confess I have re taped #6 white in the past and I bet no one died from it---yet anyway.
 
Dennis Alwon said:
Isn't that a crock. Why can you re-color larger than #6 but you can't when it is #6 or smaller. Anyone know why this is so.
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My guess is that the larger-than-#6 exception is due to the wide availability of #6 and smaller in colors. Many NEC rules and exceptions (such as white wire in cable used as hot) are formed around how equipment is manufactured.
 
charlie b said:
. Secondly, some local jurisdictions specifically forbid the use of the conduit as the EGC, and require that a separate wire be pulled for this purpose.
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This should be in 250 and 300.
 
chris kennedy said:
This should be in 250 and 300.
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Why would you say that?

A properly installed steel conduit will provide a lower impedance ground fault path than the EGC that would be pulled inside it. :)
 
iwire said:
Why would you say that?

A properly installed steel conduit will provide a lower impedance ground fault path than the EGC that would be pulled inside it. :)
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I agree 100 percent. Tell me you have never seen a poor or broken installation. I know it is very cost prohibitive, but as i have stated before, I NEVER use conduit as the sole ECG,
 
chris kennedy said:
I agree 100 percent. Tell me you have never seen a poor or broken installation. I know it is very cost prohibitive, but as i have stated before, I NEVER use conduit as the sole ECG,
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Chris I often run EGCs if the customer specifies it so we are just talking here.

1) Do you not trust your own conduit work?

If I support the conduit correctly and use the proper fittings as intended I have no problem trusting the conduit.

Have you never seen a splice come apart.

2) The CMP has no choice but to assume the conduit work will be installed correctly.
 
Bob, come on, Now tell me some other sub has never damaged your work? What if you didn't catch it. And I'm sure you have seen quality installations done by men back when it seems like there were more craftsmen that had been damaged by decades of attic crawling and remodeling. If your work is anything close to your custom car skills (Plow van),:grin: then you to are a true craftsman. I just don't need to read about anyone else getting hurt by energized conduit.
 
I use conduit as the egc on home runs all the time. But, i use the steel compression fittings. We're not allowed to use the set screw type fittings when it's used as an egc. The only problem i see with your installation is the green conductor as a neutral. It could easily be mistaken as an egc in the future by someone else...even with white tape on it.
 
Regarding the nuetral size. 215.2 requires it be not smaller than specified in Table 250.122, as well as being capable of carrying the calculated load of 220.61.

What size breaker is protecting this feeder?
 
K_Mark said:
The #6 Is Actually Larger Than Needed. The Feeder Is Sized For 3 Motors And Several Lights. The Lights Will Be The Only Load The Neutral Will Have. The Conduit Is Suppose To Be Rmc, So According To 250.118 It Is Okay To Use The Conduit. I Appreciate Everyone's Input.
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Not quite OK. The 2005 NEC requires the grounded conductor to be sized per 250.122, in the case the there is a short from hot to neutral, a undersized neutral, such as a 6 AWG, would not clear the fault.
See 215.2(A)(1)
 
Dennis Alwon said:
Isn't that a crock. Why can you re-color larger than #6 but you can't when it is #6 or smaller. Anyone know why this is so.

I must confess I have re taped #6 white in the past and I bet no one died from it---yet anyway.
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Not sure why the code only allows 4 and larger to be reidentified.
Code is code
We don't like the rules we don't agree with
They are OK for someone else
But not if it costs us time and money.
 
tom baker said:
Not sure why the code only allows 4 and larger to be reidentified.
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Many code requirements are based on the way some equipment is supplied or manufactured. The various exceptions that allow white wire in cables to be used as hots, for example, while conduit eliminates that "excuse."

Conductors 6 ga. and smaller are readily available in multiple colors, while they are typically special-order in larger sizes. Maybe the demand came before the supply, maybe the opposite, maybe the split is arbitrary.

It is what it is (whatever that means.)
 
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