NM in shallow groove

[augie47]

I am interested in others input on 300.4(E) especially in regard to log homes.

On a regular basis, I find NM cable installed in grooves cut in ceiling beams on log homes (normally to feed lighting fixtures on the bottom of the beam).
Most often these beams are then covered with tongue & groove lumber, or planks, and then, at times, with carpet or hardwood.
Requiring a metal "nail plate" or strip on these installations seems to vary from jurisdiction to jurisdiction.
(a) Do most of you see the metal plate being required?
(b) If the NM is located in a groove cut >1-1/4" in the beam is this still a "shallow groove"?

In general, inspectors in this area have required the protective plate, but it often seems contraty to what building contractors find in other jurisdictions.

You experience and input, please.

 

[infinity]

Sounds to me like the requirement for a steel plate is only when the free space below the cable is 1 1/4" or less.

 

[LarryFine]

Tthe 1.25" measurement usually refers to the nearest edge of a hole or space, so it stands to reason that the groove must be deep enough that the filler/cover itself can be at least 1.25" thick, as its rear surface would define the nearest edge of the space.

 

[augie47]

oxymoron?

oxymoron?

, ......so it stands to reason that the groove must be deep enough that the filler/cover itself can be at least 1.25" thick, ..

Thats the way I've been addressing it.
" 'stands to reason' and NEC" in same paragraph....isn't that an oxymoron?

 

[JohnE]

" 'stands to reason' and NEC" in same paragraph....isn't that an oxymoron?

I'd say so. I'm sure that nobody on this site would disagree with that.

 

[kbsparky]

I've seen many installations of this type where they used a short piece of EMT or wiremold to provide the "protection" needed in the shallow trench. Much easier to use than a steel plate, IMO.

 

[hillbilly]

I am interested in others input on 300.4(E) especially in regard to log homes.

On a regular basis, I find NM cable installed in grooves cut in ceiling beams on log homes (normally to feed lighting fixtures on the bottom of the beam).
Most often these beams are then covered with tongue & groove lumber, or planks, and then, at times, with carpet or hardwood.
Requiring a metal "nail plate" or strip on these installations seems to vary from jurisdiction to jurisdiction.
(a) Do most of you see the metal plate being required?
(b) If the NM is located in a groove cut >1-1/4" in the beam is this still a "shallow groove"?

In general, inspectors in this area have required the protective plate, but it often seems contraty to what building contractors find in other jurisdictions.

You experience and input, please.

I've wired a couple of log cabins recently, using the exact method you describe.
IMO (and the local AHJ's)...As long as the NM has at least 1 1/4" of cover, it's OK without nail plates.
Check the wires for nail penetration before the carpenters leave, or else their problem will become your problem.
steve

 

[bkludecke]

Here in the SOCAL mountains we have wired hundreds of log and open beam type homes. When we groove a beam or floor or doorjamb we either use 1/16th" steel strapping or wiremold to protect the cable. We have seen some pretty long screws and nails used in this type of construction so while the 11/4" thing may satisfy the NEC, it doesn't alwats do the job.

Bob on the left coast.

 

[allenwayne]

I've wired a couple of log cabins recently, using the exact method you describe.
IMO (and the local AHJ's)...As long as the NM has at least 1 1/4" of cover, it's OK without nail plates.
Check the wires for nail penetration before the carpenters leave, or else their problem will become your problem.
steve

We wire and protect the best we can.Take nail plates.I can`t count how many homes I have done drywall walks on where the drywallers had ripped the nail plates off and did there thing.I did a outdoor bar by a pool that had open truss design with 5/4 t&g then we wired from above the roof in emt then the framers installed 2 " insulated sheathing installed with long screws.They hit the emt and penetrated it(Had to use alot of pressure in sure)It is not our job to check each and every wire installed before the framers leave the site.The time it would take would not be cost effective in the long run.IMHO if the damage is from the framer back charge them through the builder,same for the trim carpenter and the drywaller.If we miss a jumper or a homerun (we all know it happens) Then we have to bear the weight of the drywall repairs etc.So why should we have to make sure they didn`t do the job properly.
I have set prices I charge for repairs due to damage by others.Replace damaged switch leg $195,damaged jumper $295,damaged 220 HR $495.
It goes down the line painted (contaminated panel)$395.We have to be accountable for what we do,so do the other trades.I have had no problems with this for many years.
I had a large painting firm contact me after they were back charged for 15 contaminated panels in one week,frantic about it.I calmly asked if you had to paint a wall next to cabinets what would you do ??? Answer ,mask it off.A wall next to SGD`S,Answer mask it off. OK so what`s the problem.After that it never happened again.Point made.hit the other trade in the pocket book and not spend the money we work for verifing they did the job they were paid to do in the first place.

 

[LarryFine]

Hear, hear!