Avoid drilling top plate?

[CJF]

I'm new to the forum, building my own house, and have a question without an answer. I've mounted my main panel in the garage on the wall common to the house. I'm really protective of structure, so rather than drill a bunch of holes through the top plate, I'd like to enter through the wall just under the plate and create a small soffit to conceal the wires on the other side before entering the attic. The other side is a water heater closet, so I could make it look nice. One of the reasons I'm concerned is there is a truss above the bay where the panel is located, so it doesn't have a stud directly beneath it. I don't think it's a fire safety issue since I'll already be on the other side of the garage sheetrock, and I'll follow the same spacing/capacity regulations on the holes and wire, but am I missing any other code issues? Thanks for any help!

 

[fatboy]

Welcome to the forum CJF!

What you are proposing sounds fine, as long as you don't bundle to many conductors, to tightly. I don't know how much, or how tight is too much, one of the electrical gurus can weigh in on that. You can also use adjacent stud bays to spread the number of holes in the bay above the panel.

 

[CJF]

Thanks! I sincerely appreciate the help and will be sure to follow the NEC guidelines on spacing and support.

 

[Yankee]

And read IRC 2009 302.5.3 for penetrations through the sheet-rocked wall that separates the garage from the dwelling

 

[north star]

* * *

CJF,



Welcome to The Building Codes Forum!



As to your proposed design, we have had [ only ] one of these types

of framing here......The framer did a very good job at creating a faux

soffitt in which to install the conductors to the top of the interior

electrical panel.....He did not drill a single hole in to any top plates

and all of the conductors themselves were well spaced out, so that

heat dissipation was not an issue.



& & &

 

[ICE]

Don't forget that the intersection of the wall and the attic requires a fireblock.

Spacing the cable equal to the width of the cable is enough to avoid bundling.

 

[codeworks]

don't go more than 3 romex in a 7/8 or 1 inch hole. keep them spaced so they aren't "bundled" for more than 24 inches.

 

[globe trekker]

codeworks,

Why only 3? Section E3605.4.4 in the 2006 IRC, limits the number to 2, until an adjustment

of the ampacity of the conductors is required. Just asking..

.

 

[TheCommish]

So the electrical code is concerned with limiting the number of conductors in a raceway, conduit or groped together in wood frame construction due to heating or inversely cooling of the conductors, yet here in New England the electrician runs the conductor (nonmetallic sheathed cable) from the basement up through the stud by of the exterior wall to get to the second floor and we insulate the the stud bay.

Now what, the conductors are insulated, some times totally encapsulated in foam or blow in insulation, covered with split fiberglass how much cooling is available then?

 

[Daddy-0-]

Welcome.

I often see the panel bumped into the garage 3 1/2" by framing a false wall the width of the panel all the way to the ceiling. This creates a non structural chase to hide and protect the wires. This also provides easy future access to the bundles if you ever need it. All you have to do is fireblock the top of the Chase and drywall the bump out for final.

 

[CJF]

You guys are great. I read up on the fireblocking and penetrations, appreciate the idea of the false wall, and will stick to 2 wires per 7/8 hole spaced to avoid bundling. I really appreciate the help!

 

[fatboy]

Come on back soon, keep us up to date on your progress!

 

[elowpop]

silly thinking

Since it's a interior wall you created a weird responce to a non issue. If the truss is a normal end bearing there is no load.

When you go around the plate you still will firestop so what's the point.

This will just remind everyone who sees the chase that something odd is happening here.

 

[jwelectric]

codeworks,Why only 3? Section E3605.4.4 in the 2006 IRC, limits the number to 2, until an adjustment

of the ampacity of the conductors is required. Just asking..

I think we agree hereConductors in NM cable assemblies shall be rated at 90°C (194°F). Types NM, NMC, and NMS cable identified by the markings NM-B, NMC-B, and NMS-B meet this requirement. The ampacity of Types NM, NMC, and NMS cable shall be at 60°C (140°F) conductors and shall comply with Section E3605.1 and Table E3605.5.3. The 90°C (194°F) rating shall be permitted to be used for ampacity correction and adjustment purposes provided that the final corrected or adjusted ampacity does not exceed that for a 60°C (140°F) rated conductor. Where more than two NM cables containing two or more current-carrying conductors are bundled together and pass through wood framing that is to be fire- or draft-stopped using thermal insulation or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table E3605.3.

3605.3 says from 7-9 conductors which would be 4 two conductor cables or 3 three conductor cables will be at 70%

In the 90 degree column a 14 is 25 times 70 % which would equal 17.5 and still good for a 15 amp breaker. A 12 is 30 times 70% and still good for 20 amps so where is the problem with having four two conductor cables or 3 three conductor cables twisted around each other from one end of the building to the other?

 

[ICE]

Since it's a interior wall you created a weird responce to a non issue. If the truss is a normal end bearing there is no load.When you go around the plate you still will firestop so what's the point.

This will just remind everyone who sees the chase that something odd is happening here.

The chase will be in a water heater closet, so not many people will see it. Seems like a good idea to me.

 

[CJF]

(Just a note of clarification for elowpop: The roof changes direction at the garage, so the truss DOES end on this common wall. Hence my concern because it is load bearing.)