NM in attic

[jetlag]

Im confused on 320.23 A . I have an attic space with with permanent stairs. It is made with roof trusses called attic truss. the attic is 34 ft wide but the trusses only have a 7 ft open space down the center. It seams by the code section that every conductor ran perpendicular to the joists (bottom cord) has to be drilled or have protector strips. As you know on a roof truss there are so many braces u cant just walk or crawl everywhere. In the past I have kept my perpendicular cables over near the end of rafter where the crawl space is very low maybe 18" or less. According to the code it seams none of the cables can be on top of crawl space. The reason I have done this in the past an inspector told me one time it is okay within 3 ft of the end of rafter. Was that wrong . I know about the 7 ft rule for fasten overhead.

 

[jetlag]

Will some one weigh in on this , surely some one has wired or inspected attic space with roof truses and permanent stairs. The ones ive seen had cables running every where diagonal across the trusses except down the center where there was room to put some plywood for storage.

 

[Split Bolt]

Hey jetlag, I'll weigh-in. Don't drill holes in the trusses! You may wind-up paying for the replacement of engineered trusses! I know others might weigh-in and poo poo this, but why not staple them to the bottom of the top member of the truss? Where there are multiple cables, you can take scrap pieces of romex and loop them around the cables and staple them to the bottom of the top member as well, hanging them above the floor and insulation. I have done this before and found that, if it is a neat job, the inspector didn't say a word! Also, try to stay out of that center walkway area as it will surely be floored and used for storage!

 

[M. D.]

if you run on the surface you will need protection. Having said that there are some that have argued that the rule does not pertain to your situation.
http://www.iaeifl.org/forums/ubbthreads.php/topics/971.html

 

[Split Bolt]

Just another quick thought. Try to make all runs in the same place and screw down some 2x4s on either side of your runs, making a channel.

 

[eprice]

Hey jetlag, I'll weigh-in. Don't drill holes in the trusses! You may wind-up paying for the replacement of engineered trusses!

I'll second this advice. The sheets that come with the trusses specifically say that they are not to be modified in any way. A building inspector that sees truss members drilled should require approval from the engineer who stamped the truss design. Where I have seen this happen in the past, the engineer has called for new members sistered to the members that were drilled. It was an expensive fix.

 

[construct]

I'll second this advice. The sheets that come with the trusses specifically say that they are not to be modified in any way.

I'll third that advice. I've seen this occur 4 different times and in all 4 cases the engineer's fix was 6ft members the same dimension as the bottom cord placed so that the member extended 3ft on either side of the hole and secured with 2 rows of 10d nails spaced 6" o.c. So this would be a timely and labor intensive fix.

 

[LarryFine]

I do obey the 6' rule in all attics. If I cannot drill the framing members, as with trusses, I merely run the cables alongside the members until I exceed the 6' from the access hole, then up and over the members.

It takes a bit more cable than a straighter run, but it's compliant and quick. This is similar to running cables between, say, receptacle boxes up, over, and down (or down, over, and up) instead of through studs.

 

[M. D.]

Larry he has a set of stairs six foot rule does not apply ..protection every where...

 

[LarryFine]

Larry he has a set of stairs six foot rule does not apply ..protection every where...

Ah. In that case, I would think that outside the clear center area would have no restrictions.

The wires can be stapled to the backside of the knee-wall studs for across-the-truss runs.

 

[jetlag]

Thanks split bolt

Thanks split bolt

Hey jetlag, I'll weigh-in. Don't drill holes in the trusses! You may wind-up paying for the replacement of engineered trusses! I know others might weigh-in and poo poo this, but why not staple them to the bottom of the top member of the truss? Where there are multiple cables, you can take scrap pieces of romex and loop them around the cables and staple them to the bottom of the top member as well, hanging them above the floor and insulation. I have done this before and found that, if it is a neat job, the inspector didn't say a word! Also, try to stay out of that center walkway area as it will surely be floored and used for storage!

I didnt intend to drill the trusses, I was just saying what the code allows for joists. Also according to code the over head can only be done above 7 ft high, the area im concerned with is much less. the center space meets all requirements for legal room and can be finished out. Im asking about all the wires outside of this space

 

[jetlag]

Just another quick thought. Try to make all runs in the same place and screw down some 2x4s on either side of your runs, making a channel.

yea, im looking at that as prob the best option , will take some figuring to keep the wires in least amount of channels. I think code need to be revised for roof trusses in areas where braces and heigth make adding flooring something very unlikely to happen.

 

[jetlag]

thanks larry

thanks larry

I do obey the 6' rule in all attics. If I cannot drill the framing members, as with trusses, I merely run the cables alongside the members until I exceed the 6' from the access hole, then up and over the members.

It takes a bit more cable than a straighter run, but it's compliant and quick. This is similar to running cables between, say, receptacle boxes up, over, and down (or down, over, and up) instead of through studs.

If you read the code what you suggest is not for an attic with permanent stairs

 

[jetlag]

thanks larry

thanks larry

Ah. In that case, I would think that outside the clear center area would have no restrictions.

The wires can be stapled to the backside of the knee-wall studs for across-the-truss runs.

thats what id like to do but code doesnt say outside the center area is exempt from permanent stair rule. but i think it should be

 

[augie47]

I worried about this often as it seemed a common "violation". A fellow Forum member addresses it by noting the roof truss systems do are not "floor joists" so 320.23(A) is not applicable.
Works for me.

 

[jetlag]

thanks augie

thanks augie

I worried about this often as it seemed a common "violation". A fellow Forum member addresses it by noting the roof truss systems do are not "floor joists" so 320.23(A) is not applicable.
Works for me.

The problem is roof trusses are considered as joists on the 6 ft from opening rule so what happens with permanent stairs , do you just say they are not floor joists, i think code needs some revision here

 

[jetlag]

Thanks construct

Thanks construct

I'll third that advice. I've seen this occur 4 different times and in all 4 cases the engineer's fix was 6ft members the same dimension as the bottom cord placed so that the member extended 3ft on either side of the hole and secured with 2 rows of 10d nails spaced 6" o.c. So this would be a timely and labor intensive fix.

I want to state once more I dont intend to drill in a roof truss, I was just stating what the code says is allowed for wiring but its not intended as guilde for non drillable members

 

[augie47]

The problem is roof trusses are considered as joists on the 6 ft from opening rule

considered by whom ? Code article ?
We do require protection within 6 ft of the scuttle-hole so I will agree, by practice, trusses are considered as joists in that case, but I fail to back that up with NEC.

so what happens with permanent stairs , do you just say they are not floor joists, i think code needs some revision here

TN inspectors have been advised to treat pull down stairs with truss systems as scuttle-hoes (6 ft rule)
As far as the need for revision, I certainly agree with that.
I have presented the subject at two regional IAEI Seminars only to be advised that, next to roof truss stapling, 320.23 was one of the "most violated" (and accepted).
To enforce it in an attic filled with ductwork and plumbing and almost impossible to navigate does seem ridiculous. To ignore it in with a roof truss system that is easily walked seems improper also.
320.23 does need to be addressed with modern day building standards in mind.

 

[stevenje]

The problem is roof trusses are considered as joists on the 6 ft from opening rule so what happens with permanent stairs , do you just say they are not floor joists, i think code needs some revision here

I agree. When you come right down to it what is the difference of having a permanent stairway or just an attic access hole that you access with a ladder. The possible damage to the wiring will happen in either case, stairway or not.

 

[jetlag]

thanks augie

thanks augie

considered by whom ? Code article ?
We do require protection within 6 ft of the scuttle-hole so I will agree, by practice, trusses are considered as joists in that case, but I fail to back that up with NEC.

TN inspectors have been advised to treat pull down stairs with truss systems as scuttle-hoes (6 ft rule)
As far as the need for revision, I certainly agree with that.
I have presented the subject at two regional IAEI Seminars only to be advised that, next to roof truss stapling, 320.23 was one of the "most violated" (and accepted).
To enforce it in an attic filled with ductwork and plumbing and almost impossible to navigate does seem ridiculous. To ignore it in with a roof truss system that is easily walked seems improper also.
320.23 does need to be addressed with modern day building standards in mind.

well 320.23 just refers to all bottom members as joists and doesn't say if they mean floor joists or if ceiling joists for room below. they call it a joist or floor within 6 ft of scuttle and if you have to have it rather truss roof or not saying a truss is not a joist is not going to exempt it . actually its called a bottom chord on a roof truss.