GEC in conduit

[al hildenbrand]

I have never seen this happen, and it is not the purpose of the GEC of premises wiring systems.

It may happen, I could only see that as a very rare coincidence.

I suspect that events like a tree pulling down a drop and peeling a point of attachment and service entrance off the side of a building will have a percentage that break the neutral first.

 

[Pierre C Belarge]

In NC we are required to run #4. Not to many cases where it would be subject to damage. He is sleeving it to hide it only I think.

I understand, that could be possible.

 

[Pierre C Belarge]

I suspect that events like a tree pulling down a drop and peeling a point of attachment and service entrance off the side of a building will have a percentage that break the neutral first.

I have seen this occur, with the GEC becoming the neutral/grounded conductor (when connected to city water that is run between buildings).

 

[al hildenbrand]

I have never seen this happen, . . .

I keep thinking of 250.4(A)5

Awhile back, the Metro had a major Plains storm come through. I went to a home with a 100 A 120/240 V service. This one was in EMT and had the mast yanked off the side of the house by a tree.

The meter and socket were still on the house, and the meter socket hub was broken. I watched as a jiggle shorted one of the hot legs at the broken hub, a small arc occurred, and the neighborhood went dark as the transformer OCP operated. When I put my hand on the #6 GEC that went from the service off to the municipal water service at the other end of the house, it was still uncomfortably warm 2 or 3 minutes later.

 

[jetlag]

thanks jwjrw

thanks jwjrw

In NC we are required to run #4. Not to many cases where it would be subject to damage. He is sleeving it to hide it only I think.

Every one says I am wrong to use #4 , all that is required is #6 by the NEC and my ahj is also wrong. I am close to you in GA and I might still be correct with the #4 if Ga has the same ammendment . Every place Ive been in GA required the #4 .
Read the post "how many ground rods " to see how I got pounded

 

[roger]

In NC we are required to run #4. Not to many cases where it would be subject to damage. He is sleeving it to hide it only I think.

Not in my part on NC.

Roger

 

[roger]

Well I got flagged for that and the AHJ said I was parallelling the ground, that I had to take the emt off or use pvc.

Leaving the 250.64(E) coversation for a minute, ask the inspector what's wrong with paralleling a GEC and where is it prohibited. This is one case where as many paths as possible can be an advantage and Soares even show examples of it.

Now back to 250.64 (E), you would have had to make the 37 mile trip anyways.

As far as using PVC, that is what I do and if there is a question of physical damage protection you can use sched 80.

Roger

 

[jetlag]

Not in my part on NC.

Roger

I see it comming , debate over #4 in NC . I Will be checking on the outcome of that :grin:

 

[roger]

I see it comming , debate over #4 in NC . I Will be checking on the outcome of that :grin:

Nope, no need to debate, you can read all the NC amendments to the NEC by clicking HERE and you will only find one amendment to article 250 which is

AMENDMENT 250.50

Delete NEC 2008 text and replace with:
250.50 Grounding Electrode System. If available on premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.

Roger

 

[jetlag]

Leaving the 250.64(E) coversation for a minute, ask the inspector what's wrong with paralleling a GEC and where is it prohibited. This is one case where as many paths as possible can be an advantage and Soares even show examples of it.

Now back to 250.64 (E), you would have had to make the 37 mile trip anyways.

As far as using PVC, that is what I do and if there is a question of physical damage protection you can use sched 80.

Roger

I would not have had to go back because he didnt flag me for the bond ,he either doesnt know the code or didnt care if the other end was bonded , he want the EMT gone. He flagged me for wrong violation. You are correct , to start an argument I would have had to go back and bond the other end, I wish I had done that now .

 

[roger]

I would not have had to go back because he didnt flag me for the bond ,

Jetlag, just because an inspector doesn't flag you or incorrectly flags you for an infraction doesn't relieve you of your responsibility of doing a propper installation and by not bonding both ends of the ferous raceway you had a violation.

Roger

 

[George Stolz]

...to start an argument I would have had to go back and bond the other end, I wish I had done that now .

There's been more than once that an inspector has misstated what problem he had with the installation he did not pass. Better to have a good conversation about the installation over the phone, establish what is in each guy's head, and then make the 37 mile drive once.

Edit to add: If you had driven over there, bonded the raceway per code, and the inspector returned to find the conduit still there, you know you would have failed again. Know what I mean?

 

[lakee911]

I watched as a jiggle shorted one of the hot legs at the broken hub, a small arc occurred, and the neighborhood went dark as the transformer OCP operated. When I put my hand on the #6 GEC that went from the service off to the municipal water service at the other end of the house, it was still uncomfortably warm 2 or 3 minutes later.

I'm guessing that the neutral had already broken and the fault current traveled through the metal water pipes to a neighbors house and back to the transformer through their neutral.

Jason

 

[glene77is]

Good work jumper, I had a bonding lock nut at the top but didnt dream the code would require both ends bonded . Seems to me one end bonds both

Jet,
The 'bonding' at both ends forms a Faraday Shield of the Capacitive type,
which passes high frequency pulses (lightning) towards the earth with minimum impedance.

Bonding only at the top will form an Inductive type Faraday sheild, which will buck the lightning pulse.

 

[al hildenbrand]

I'm guessing that the neutral had already broken and the fault current traveled through the metal water pipes to a neighbors house and back to the transformer through their neutral.

Jason

As I recall, the neutral was intact. The transformer was down the alley two spans, however.

But you're right about the current path. The current took all available paths, and these were multiple neighbor's neutral/GEC/water pipes, all connected to the same transformer, so they were all in parallel. IMO, that low parallel impedance plus the water pipe/GEC at the house with the short at the meter hub will have half, or more, of the fault current, when the grounded service conductor is intact, and the transformer is a ways down PoCo #4 hard drawn Cu open conductor secondary.

 

[readydave8]

Every one says I am wrong to use #4 , all that is required is #6 by the NEC and my ahj is also wrong. I am close to you in GA and I might still be correct with the #4 if Ga has the same ammendment . Every place Ive been in GA required the #4 .
Read the post "how many ground rods " to see how I got pounded

In this part of Georgia inspector passes #6, Georgia Power ok, but EMC requires #4. They say that they're on a different code than us, I've heard them mention the "Life Safety Code." I don't know if that's true, just that it's their answer.

 

[roger]

In this part of Georgia inspector passes #6, Georgia Power ok, but EMC requires #4. They say that they're on a different code than us, I've heard them mention the "Life Safety Code." I don't know if that's true, just that it's their answer.

This would have nothing to do with NFPA 101 (AKA The Life Safety Code).

Roger

 

[readydave8]

This would have nothing to do with NFPA 101 (AKA The Life Safety Code).

Roger

that's what I suspected but never cared enough about it to follow up.

thanks.

 

[jetlag]

In this part of Georgia inspector passes #6, Georgia Power ok, but EMC requires #4. They say that they're on a different code than us, I've heard them mention the "Life Safety Code." I don't know if that's true, just that it's their answer.

The EMC are the ones that started wanting the # 4 from the rod to pass through the disco and the meter with out being broken , it had to be pulled through the ground bar and up the mast out the weather head. It was a royal pain to wire it . It went on a few years before they were forced to stop requiring it. They were parallelling the neutral . They EMC requires #4 here also and that is what caused me to start using it on GA power. I forgot GA power goes by the NEC , EMC sets their own rules sometimes