NM between joist bottom and sheet rock

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Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Why isn't this considered a cut-and-dried violation of 300.4(D)?

The NM can't be secured 1.25" away if it's captive at 3/4"? :confused:
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

trusses are often 24 inch centers.Strapping is run across the trusses at 16 inch centers...it keeps any potential sagging of the sheetrock minimalized.
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That sounds reasonable.

That reminds me. I don't remember what the requirements are but I think the sheet rock fasteners needs to be 6 or 8 inches at the edge and I think 12 along the stud or joist. Here anyway.

If this is true there too then how are the edges of the sheet rock handled?
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Cause they're perpendicular instead of paralell.
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Originally posted by iwire:

Does anyone here know?
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I bet it was some woodcutters union that pushed for this back in the oldern days. :D

For you guys that don't get this luxury building method think about how easy it is to add wiring when you can snake under the joists in reno jobs. I'll try to take some pictures next week when I am roughing an addtion.
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

For you guys that don't get this luxury building method
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Now come on Scott, I don't see any problem with this as long as you're using AFI's in the garage. :D
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Originally posted by physis:
If I use NM where there's even the remotest possibility that something inprobable could happen the building department will cordon off the area and evacuate everybody in a two block radius after they've called to have the grid shut down.
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:D

I know your exaggerating however after reading posts from some areas I do not think you are that far off the mark. :p
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Why isn't this considered a cut-and-dried violation of 300.4(D)?

The NM can't be secured 1.25" away if it's captive at 3/4"?
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This method of securing the cables to the underside of the joist adjacent to furring strips is acceptable according to the 2005 NEC. It only need to be 1 1?/4" away from the edge of the furring strips not from the back side of the sheetrock.

This is according to the summary of changes for article 300 in the NEC 2005 Handbook:

300.4(D): Revised to add a reference to furring strips, clarifying that even though the strips may not be framing members, the 1 1?/4" clearance from any edge subject to nail or screw penetration is required to be maintained.

There is also a good photo of this on pp.258 in the Handbook as previously mentioned.
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

What do you guys think happens when wires are ran on block walls ? We trap the nm between the block and the drywall.We hold the wire 1 1/4 inches from where it will be nailed (the 1x2).As to why some use strapping,all i can say is some cared about leveling out the surface.Perhaps trusses are being made a little better.I have seen many bowed ceilings where nobody used them.Perhaps its a code where some live.As long as the wire is out of nail path there is no problem so why fix it ?
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

I have lost count of the amount of homes I have wired in central florida and have never seen furring running perpendicular to the trusses on the bottom ( room side ) that is.Now engineering runners on the top of the bottom cord of a truss is used all the time but in 2x4 and 2x6`s on floor trusses.But this is in the area of a structual member that is on the opposite side of the board that is going to be sheetrocked.
When convenionally framed what is used here is is a anti twist strsp that are criss crossed at 4 ft intervals gong from top of joist to bottom of adjoining joist and vise versa.IMO that would be the only reason on conventionally framed floor joists to run strapping perdendicular to avoid twisting of the joists.
We rarely encounter conventionally framed homes here,all trusses for floors sissor or tgi style.Standard roof trusses with engineered 2x4`s
I call rat runners.
Some areas I have worked in requre running all nm parralel with theses 2 x 4 and 90 across the side of the truss member to destination.
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Have any of the naysayers (George) looked at the handbook picture? Also in Massachusetts the spacing requirement in 300.4 (D) for this installation is reduced from 1 1/4" to 3/4". Talk about living the dangerous life! :D
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

I'm not saying somebody's bound for the seventh level of hell for not following NEC on this. I'm just saying, it's a violation. Drama, jeez. :D

What's the difference between the backside of the drywall and the surface of the furring strips, anyway?

Edit Error S

[ June 07, 2005, 10:26 PM: Message edited by: georgestolz ]
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Originally posted by georgestolz:
I'm not saying somebody's bound for the seventh level of hell for not following NEC on this. I'm just saying, it's a violation.
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George a violation?

Please point to the specific section this violates. :p

Not just 300.4 but a specific section of 300.4.

[ June 08, 2005, 05:33 AM: Message edited by: iwire ]
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Are we missing the reason for the 1 1/4 rule ? We are trying to protect the wire from a 1 1/4 inch drywall screw.Should a wire be ran thru a hole in a 2x4 and by accident it be the same exact location the board hanger places a screw we are still safe from being hit by a little under1/2 inch.When ran beside a firing strip on a block wall the hanger would need too miss his targed by about 2 inches.In some areas the wire was even being allowed to get stapled onto the 1x2.In this case yes we have a wire stapled onto a floor truss or beam but that beam is not where the screw goes.The screw goes into the 1x2.
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Are you perhaps misreading 300.4 ? it talks about shallow grooves and notches but that is not what we have here.Yes ,like Bob asked,just where in 300.4 do you see a violation ?

[ June 08, 2005, 06:08 AM: Message edited by: jimwalker ]
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Originally posted by iwire:
George a violation?

Please point to the specific section this violates. :p

Not just 300.4 but a specific section of 300.4.
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300.4(D) Cables and Raceways Parallel to Framing Members. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or studs, the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (1.25 in.) from the nearest edge of the framing member where nails or screws are likely to penetrate. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by nails or screws by a steel plate, sleeve, or equivalent at least 1.6 mm (1.25 in.) thick.
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Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Originally posted by georgestolz:
so that the nearest outside surface of the cable or raceway is not less than 32 mm (1.25 in.) from the nearest edge of the framing member
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George there is no specified direction.

All you have to be is an 1.25 from the edge of the strapping, I do not have to be 1.25" from the inside face of the Sheetrock. :)
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

I remember when it was allowed to staple right against the furring ;) Now we have stand offs to keep them 1.25 ins from the furring.
Hillsboro county fla.allows the nm to be stapled right on top of a 1x4 base furring but has to be 1 1/4 from vertical furring :confused:
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Man this sucks. How come I have to use EMT? Your guys's inspectors are all "eh, just fling it over some of those parts of the building thingies". "The sheet rock guys 'll know what to do".

:D :D
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

i can see both points of view here.But.....1 1/4" from the side of the strip will protect the wire from the nail the homeowner is gonna drive to hang a picture up how? this would be more likely than the drywall guys hitting it i would think. I know we cant control stuff like this, but sounds like a problem waiting to happen.
 
Re: NM between joist bottom and sheet rock

Re: NM between joist bottom and sheet rock

Originally posted by georgestolz:
300.4(D) Cables and Raceways Parallel to Framing Members. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or studs
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Note that furring strips are not in the list of framing members; also note that furring strips and the wiring in discussion here, are run perpendicular to the above-mentioned framing members.

In my opinion, this is the same situation as wiring behind drywall where the space is shallow, as has been discussed. Just keep the wiring away from the furring by a couple of inches.

By the way, joists and trusses are furred to allow for shimming to produce a flatter ceiling, as Mr. Walker touched upon. Joists and trusses are not known for perfection.
 
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