Some things will never change...

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peter d

peter d

Senior Member
Location
New England
I was at Home Depot today (to pick up some items that the supply store didn't have :roll: ) and lo and behold some electricians were working overhead. They were pulling some new circuits into the existing conduit and wireways.

Well, they were running #6 for voltage drop reasons but they were pulling a #10 ground. I guess they must have forgotten about the NEC.

And then there was one of the workers violently jerking the snake and conductors as he pulled the new conductors past the existing live ones in the conduit. I was waiting for the fireworks to start.

I don't know why I bother ranting about this. I guess I just expect too much. Granted, this forum has given me volumes of knowledge I never had before. Ranting won't do any good anyway.
 
Re: Some things will never change...

Was it metallic conduit?. Is #8 going to be required if the conduit by itself will satisfy the code as an equipment ground? What I do know is that the equipment grounding for the circuit must be capable of delivering enough fault current to trip the breaker and clear the fault. That said, is the combination of the two paths enough to clear this in a fault situation, and therefor the code become satisfied as to the size of the equipment bonding.
 
Re: Some things will never change...

If they were pulling #6 "for voltage drop", then why are you assuming that #10 ground was not sufficient? You sze an "equipment ground conductor" per the rating or setting of the overcurrent device, not the size of the the wire being pulled (table 250-122).
Out!
 
Re: Some things will never change...

Originally posted by lawelectric:
You sze an "equipment ground conductor" per the rating or setting of the overcurrent device, not the size of the the wire being pulled
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Not quite. See 250.122(B) If the ungrounded conductors are increased in size, the EGC, where installed must be increased proportionately. ;)
 
Re: Some things will never change...

John is correct. The EGC must be increased in size when the circuit conductors are increased for voltage drop. The undersized EGC would be a violation, but if the conduit were metallic than you could skip pulling the undersized EGC and away goes the violation.
 
Re: Some things will never change...

Originally posted by infinity:
The EGC must be increased in size when the circuit conductors are increased for voltage drop.
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And for the same reason: the non-increased EGC might have too much voltage drop to assure OCP operation, if the run is long enough to need the "super-sizing."
 
Re: Some things will never change...

"That said, is the combination of the two paths enough to clear this in a fault situation, and therefor the code become satisfied as to the size of the equipment bonding."
I can agree that this may provide the effective ground fault current path per 250.4(A)(4), but this is not a code rule as you state. If you install an EGC it has to be sized per 250.122 and if the ungrounded conductors are increase in size (for any reason) then the EGC is increased by the same proportion.
 
Re: Some things will never change...

The thing that bugs me about this rule:

How many people are going to just omit the ground wire and use the conduit only for a ground? For example, say the inspector catches these guys pulling a #10 ground, and he says #10 is too small. Make it a #6 or pull it out. Of course, they are going to just pull out the #10 and use the conduit as a ground. I think everyone would agree the conduit and a #10 is better than the conduit alone.

I guess my point is I don't think this rule will make installations safer. I think now more installations will rely on only the conduit as the ground path.

Steve
 
Re: Some things will never change...

Originally posted by steve66:
The thing that bugs me about this rule:

How many people are going to just omit the ground wire and use the conduit only for a ground?
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First thing I thought of when I read Pete's description. :D

In this case a home depot (A steel framed structure) I would omit the EGC conductor and use the EMT as the EGC and not worry about it for a moment.
 
Re: Some things will never change...

Originally posted by iwire:
I would omit the EGC conductor and use the EMT as the EGC and not worry about it for a moment.
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If there was an original EGC in the conduit I would have used that for pulling instead or trying to push a steel fish tape down the existing conduit.

[ January 04, 2006, 09:43 AM: Message edited by: tkb ]
 
Re: Some things will never change...

Peter

I agree with you according to code they should have pulled a #6.
because this was a voltage drop issue.

And even if it where because of the conduit being to small they still should pull a #6 simply because the NEC says to.

I always thought we where certified because we had a good knowledge of the field we are working in and with this knowledge we are suppose to be able to work common sense problems out.Like understanding the code and why it says what it says and to be able to work around its contradictions.

It is not technically correct to up size the equipment ground when up sizing for conduit fill alone if there is no voltage drop issue because the heating problem has been taken care of by up sizing the conductors which have the load on them.The equipment ground has no load on it and will not add heat to the raceway system.
 
Re: Some things will never change...

Originally posted by ronaldrc:
It is not technically correct to up size the equipment ground when up sizing for conduit fill alone if there is no voltage drop issue because the heating problem has been taken care of by up sizing the conductors which have the load on them.The equipment ground has no load on it and will not add heat to the raceway system.
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Up sizing the EGC never has anything to do with heating.
 
Re: Some things will never change...

Originally posted by ronaldrc:It is not technically correct to up size the equipment ground when up sizing for conduit fill alone. . . .
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We do not upsize anything because of conduit fill.

But I think you might be referring to using a larger conductor because of having more than three current-carrying conductors in the same conduit. But when we do this, what is happening is that we are derating the ampacity of the conductors. We use this process to discover what the ampacity of a conductor will be, and compare it to what ampacity is needed. If we upsize for this reason, we are not really "upsizing." We are just "sizing." We are establishing the ampacity. It is only when we pick a conductor that is larger than is needed for ampacity considerations that we must also upsize the EGC.

And I agree with Tom: It would not matter if you are taking any credit for the raceway as a fault path. If you pull an EGC, and if you upsize the phase conductors, you must also upsize the EGC.
 
Re: Some things will never change...

"Not quite. See 250.122(B) If the ungrounded conductors are increased in size, the EGC, where installed must be increased proportionately."

If they were pulling #6 for voltage drop, then we can assume the overcurrent rating was 40 or less. Table 250-122 says #10 is good for 30,40,60, so why would #10 not satisfy 250.122(B)if it's already rated for up to 60A
 
Re: Some things will never change...

Originally posted by lawelectric:
If they were pulling #6 for voltage drop, then we can assume the overcurrent rating was 40 or less. Table 250-122 says #10 is good for 30,40,60, so why would #10 not satisfy 250.122(B)if it's already rated for up to 60A
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If they are pulling 6 AWG circuit conductors for a 14, 20 or 30 amp circuit if they choose to run an EGC conductor they will have to pull a 6 AWG EGC to satisfy 250.122(B).

However if they pulled the same circuit conductors for a 60 amp circuit a 10 AWG would be sufficient. :D

(B) Increased in Size. Where ungrounded conductors are increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately according to circular mil area of the ungrounded conductors.
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The proportion of ungrounded to EGC with 14, 20 and 30 amp circuits is one to one.

That ratio must stay the same no matter how odd it seems.
 
Re: Some things will never change...

I'd just yank the wire out and use the emt for the bonding. On other projects whereever possible, I will still pull in an equipment ground conductor. In this type of situation, I would myself have to go with the system that was real common when I first got into the trade, which was to rely on the conduit system for the bonding means.
 
Re: Some things will never change...

Did peter ask the sparkies at HD why they were pulling no. 6? They could have just been pulling a 60amp circuit.

I have done this before for lighting, and fused the ballasts individually.
 
Re: Some things will never change...

Using only the conduit as a ground worries me the most in wood frame buildings.

If one coupling comes apart, the ground is lost. And just when it is needed the most.
 
Re: Some things will never change...

Originally posted by jbwhite:
They could have just been pulling a 60amp circuit.
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True, they could have been. No, I didn't ask, but I highly doubt it too. They were pulling a black and a white. I'm not aware of too many 60 amp, 120 volt circuits. But I could be wrong. They were pulling in a conduit that led to a panel several hundred feet away, so I am 99.9% sure the conductors were being upsized for voltage drop.
 
Re: Some things will never change...

So did you just get tired of waiting for the sparks or finally had to go back to work or did they get it pulled without incident?

I love to watch the pro's personally. Sometimes I learn something and other times I'm just amused beyond beleif. :D
 
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