Best Practice for Floor Penetration of Multiple Branch Circuits

[paullmullen]

I have a situation in which I will have an upstairs 48-position MLO circuit breaker panel in a residential application. Feeders will come from above, branch circuits exit at the bottom of the panel and pass through the floor before being routed to the various loads. NM cabling to all branch circuits.

What are the best practices for managing the panel and floor penetration? Here are some things I'm considering:

1) Install a short (< 24") wireway for through the floor and firestop around it. All circuits exit breaker panel through pre-punched knock-outs with listed bushings and then they all pass through the rest of the open stud bay, entering the fire-stopped wireway to go through the floor. I'd probably put a couple caddy bars in place in the open stud space for required 334.40 support.

2) Cut a larger hole in the bottom of the breaker panel (within manufacturer's published limits) and attach a flanged wireway from the breaker panel through the stud space and through the floor (firestopped at the floor). Then pass all branch circuits through that wireway. (Probably triggers some derating 310.15(B)(3) ampacity correction since the wireway would be >24" long.)

3) Drill 48 holes in the floor and pass each wire through its own hole. (OK, just kidding.)

Thoughts?

Paul

 

[NJTommy]

Hire someone else to do it, hahahaha kidding. have you thought about using different wire? I know they make MC that has multiple circuit's in one cable. Its not like 3 wire where you share a neutral but it has separate neutrals for each circuit. It would require fewer holes but more planning. Is the ceiling below sheetrock? You could run conduit to pull boxes? Just a few thoughts. That's not easy one. When I am in situations like that I always feel I going regret what ever I choose. Good like and happy holidays!

 

[curt swartz]

I have never seen a 48 space load center unless its a 24/48.

Do you really have 48 NM cables? If so good luck getting them into one end of a standard 14" wide load center.

Not sure why you are making this so complicated. This is a normal installation to have cables/raceways run through the top and bottom plates,

For 48 cables just drill 12 holes and run 4 cables through each hole.

 

[Little Bill]

I would seriously look at why 48 NM cables. Sounds like overkill for some circuits. Every item in the house doesn't need it's own circuit. Multiple rooms can share the lighting, for example.
Even so, it's not hard. Do as Curt suggested and just drill holes and divide the NM so there is no more than 4 per hole.

 

[paullmullen]

I have never seen a 48 space load center unless its a 24/48.

Do you really have 48 NM cables? If so good luck getting them into one end of a standard 14" wide load center.

Not sure why you are making this so complicated. This is a normal installation to have cables/raceways run through the top and bottom plates,

For 48 cables just drill 12 holes and run 4 cables through each hole.

Yeah... in this case it has to do with the geometry of the wall. Otherwise I'd go top, bottom sides, etc. Thanks for the idea.