Wire Depth Near Roof

[Green Machine]

I had a conversation with a roofer I've done some work with: he has now twice had one of his guys nail through wire that is too close to his roof deck. He asked how far from his roof deck or wood had to stay. He wanted to know if he really was responsible for knowing where wires are under a roof deck.

I at first assumed 1¼", since that is the distance in walls, but he pointed out that his nails could go as far as 2" to 2½".

Is there a separate code for roof decks from walls?

 

[rc/retired]

300.4(E) 1" and a half

Ron

 

[don_resqcapt19]

300.4(E) 1" and a half

Ron

But that only applies to metal-corrugated sheet roof decking....not likely to be driving nails in that type of roof deck.
The first draft is removing the metal-corrugated part, making it apply to all roof decks, but the distance is still 1.5".

 

[Hv&Lv]

Why is he using such long nails? They sell them shorter..

 

[Little Bill]

I had a conversation with a roofer I've done some work with: he has now twice had one of his guys nail through wire that is too close to his roof deck. He asked how far from his roof deck or wood had to stay. He wanted to know if he really was responsible for knowing where wires are under a roof deck.

I at first assumed 1¼", since that is the distance in walls, but he pointed out that his nails could go as far as 2" to 2½".

Is there a separate code for roof decks from walls?

I can't recall ever running my NM up near the roof deck. Why are you running it that high?

Also, someone needs to mark, or chalk, some lines to know where to nail. They should only be hitting the trusses or rafters, not shooting nails into the decking where there isn't anything to nail to.

 

[retirede]

I can't recall ever running my NM up near the roof deck. Why are you running it that high?

I’ve seen boxes with keyless fixtures attached to roof rafters in attics.

 

[Little Bill]

I’ve seen boxes with keyless fixtures attached to roof rafters in attics.

I have too, but not usually where a roof nail could hit it.

 

[retirede]

I have too, but not usually where a roof nail could hit it.

As long as common sense is used when routing the cable, you’re right.

 

[acin]

I have too, but not usually where a roof nail could hit it.

what about the lags they attach solar panels with

 

[jmellc]

I’ve seen boxes with keyless fixtures attached to roof rafters in attics.

I did a job on lights at a church, in vaulted ceiling. Had some kind of oversized octagon boxes in ceiling. Must have been just below roof panel because 1 had a nail shot into it. I had no practical way to remove it, so I put a wire nut on it.

 

[jmellc]

I can't recall ever running my NM up near the roof deck. Why are you running it that high?

Also, someone needs to mark, or chalk, some lines to know where to nail. They should only be hitting the trusses or rafters, not shooting nails into the decking where there isn't anything to nail to.

I've seen countless attics with roofing nails missing rafters by an inch or so, or skimming the side.

 

[Fred B]

I can't recall ever running my NM up near the roof deck. Why are you running it that high?

Also, someone needs to mark, or chalk, some lines to know where to nail. They should only be hitting the trusses or rafters, not shooting nails into the decking where there isn't anything to nail to.

Once the plywood decking is in place they are just shooting roof nails as the shingles are needed into the ply not to the rafters. seen many porcupine roofs (two layers of roofing) and trying to negotiate a low attic and not pierce the top of my head.

Some roofers are screwing down the decking with 2.5 or 3 in deck screws not nails so even if you drilled trough the rafter to a minimum allowed depth it is likely to get hit. But also seen where guys have gone in, usually handymen, and sliding NM over the rafter between the purling and the roof deck, no holes to drill and no staples to pound in, to put in some attic lighting, that's easy to hit.

 

[don_resqcapt19]

I can't recall ever running my NM up near the roof deck. Why are you running it that high?

Also, someone needs to mark, or chalk, some lines to know where to nail. They should only be hitting the trusses or rafters, not shooting nails into the decking where there isn't anything to nail to.

The shingles are attached to the decking...very few of the nails will line up with a truss or rafter.

 

[Little Bill]

The shingles are attached to the decking...very few of the nails will line up with a truss or rafter.

I wasn't referring to the nails for shingles. They aren't 2" long. I was talking about the nails that hold the decking to the trusses/rafters.