Anyone ever get failed for to many wires in a drilled hole?

[macmikeman]

And I have my own little opinion about it all. We learn how many nm conductors can go in the hole before we start de-rating. We can translate that to the number of cables. It is all scientifically done via simple calculations, except the whole concept of the number of cables passing thru a hole drilled in a 1-1/2" wide wood member causing overheating problems is pure speculation in the first place. Especially when you have 16" of air space to bleed heat off before they go thru the next hole. And the holes could be 2"" diameter with 5- 14-2 cables and by the way we currently interpret the code, this would be a fire hazard, except it is not one in reality.... If anything there should be some added language regarding fill volume of the holes, so at least a larger hole with a few more than 4 cables would still be doable, without de-rating, as long as it did not go over a certain volume fill.

 

[JWinters]

My take.

My take.

Im just starting my second year in the field and my E2 tells me that on a ruff in we only put 60% for derating for heat build up.

 

[infinity]

And I have my own little opinion about it all. We learn how many nm conductors can go in the hole before we start de-rating. We can translate that to the number of cables. It is all scientifically done via simple calculations, except the whole concept of the number of cables passing thru a hole drilled in a 1-1/2" wide wood member causing overheating problems is pure speculation in the first place. Especially when you have 16" of air space to bleed heat off before they go thru the next hole. And the holes could be 2"" diameter with 5- 14-2 cables and by the way we currently interpret the code, this would be a fire hazard, except it is not one in reality.... If anything there should be some added language regarding fill volume of the holes, so at least a larger hole with a few more than 4 cables would still be doable, without de-rating, as long as it did not go over a certain volume fill.

Actually it has been proven that when the hole is fire or draft stopped a problem may exist and that's why this was added to the NEC. When NM cables were tested within a fire or draft stopped hole and loaded, the area of the cables that were within the hole had a temperature that exceeded the rating of the cable.

But as with you I'm skeptical that this would actually matter in a real world application.

 

[George Stolz]

Im just starting my second year in the field and my E2 tells me that on a ruff in we only put 60% for derating for heat build up.

Can you elaborate?

 

[macmikeman]

Actually it has been proven that when the hole is fire or draft stopped a problem may exist and that's why this was added to the NEC. When NM cables were tested within a fire or draft stopped hole and loaded, the area of the cables that were within the hole had a temperature that exceeded the rating of the cable.

But as with you I'm skeptical that this would actually matter in a real world application.

Yeah, I read all about the "testing" that was performed in order to come to this conclusion and later code related to the testing. I am of the opinion that the testing method was quite suspect. The codewas changed without any empirical data to back up the experimentation. You should see some of the experiments I was able to concoct with my junior wizard science kit and Dad's mower gas when I was a teenage scientist myself....

 

[infinity]

Yeah, I read all about the "testing" that was performed in order to come to this conclusion and later code related to the testing. I am of the opinion that the testing method was quite suspect. The codewas changed without any empirical data to back up the experimentation. You should see some of the experiments I was able to concoct with my junior wizard science kit and Dad's mower gas when I was a teenage scientist myself....

LOL, you're probably right about the scientific testing. :roll:

 

[mivey]

I think the real question is: who is Paul Abernathy?

He took some heat in a thread a while back. Basically some took offense at how involved the inspectors in Richmond get. Not really Paul's fault as that is just the way they do it up there.

Seems a bit of over-kill to me as well but we do it different down here. If the inspectors here did what they do in Richmond, they would be accused of getting all up in your business. Just a difference in areas of the country.

I was just picking at Paul a little.