Wiring method for above ceiling grid

[Krusscher]

Coming from Industrial I didn't deal to much with commercial wiring.
1. I have to run a 50 amp 4 wire circuit down a hall above ceiling grid about 60 feet and to box outside. I am still unsure if it needs to be fire rated but it is not a plenum and there is quite a bit of MC running around up there. What would be my best flexible wiring method to achieve this?

2. I do have to go through some walls so I am assuming where I do that I need to set a box and run emt to the other side to another box?

3. None of the current penetrations have fire caulk around them so I am assuming I won't have to do that either?

 

[letgomywago]

You can do mc the the whole way even through the walls.

 

[tom baker]

Good question. You can use any wiring method that’s allowed for the occupancy. Example EMT yes, NMB no.
No need for a box
Just because there is no fire caulk does not mean it’s not required. You need to know about the building construction and firewalls

 

[Krusscher]

Would it make sense to make up a FMC for this? not sure how much of a pain that would be but I can't find 6/4 MC around me. Also I am going to try to run it down a wall and come out to a surface mounted box on the sheet metal outside. Can I bring the mc/fmc right to the back of the box or would I have to use some other wiring method to run it down the wall to the outside?

 

[LarryFine]

. . . I can't find 6/4 MC around me.

6/4 Copper MC Cable w/ Ground

6/4 Copper MC Cable w/ Ground

www.wireandcableyourway.com

 

[Krusscher]

6/4 Copper MC Cable w/ Ground

6/4 Copper MC Cable w/ Ground

www.wireandcableyourway.com

Seems a bit pricey to me but I guess that's just the Dutch in me.

 

[letgomywago]

Would it make sense to make up a FMC for this? not sure how much of a pain that would be but I can't find 6/4 MC around me. Also I am going to try to run it down a wall and come out to a surface mounted box on the sheet metal outside. Can I bring the mc/fmc right to the back of the box or would I have to use some other wiring method to run it down the wall to the outside?

No it'll cost more especially considering labor. Either buy the mc or do emt but the mc even at increased cost of material will be cheaper overall since no need for pull boxes and over twice as fast to install.

 

[electrofelon]

Seems a bit pricey to me but I guess that's just the Dutch in me.

Well you would only need # 8 MC for 50 amps. Or this aluminum is about half the price of that #6 CU

6/4 MC Cable w/ Ground, Aluminum Conductors

6-6-6-6-6 Metal Clad Cable w/ ground, aluminum armored stranded aluminum conductors. Sold in 250ft or 1,000ft spools. Buy Online. Ships Same Day.

www.wireandcableyourway.com

 

[roger]

Would it make sense to make up a FMC for this?

Nope, MC or AC is fine.

 

[kwired]

Good question. You can use any wiring method that’s allowed for the occupancy. Example EMT yes, NMB no.
No need for a box
Just because there is no fire caulk does not mean it’s not required. You need to know about the building construction and firewalls

Is possible to have occupancy where NM cables can be used, but NM cable is not allowed in suspended ceilings other than in dwellings. Why dwellings, IDK. I mean we sleep at night in dwellings and is not a problem but most other places we don't sleep there but it is apparently a fire/smoke hazard if not in a dwelling??

 

[letgomywago]

Is possible to have occupancy where NM cables can be used, but NM cable is not allowed in suspended ceilings other than in dwellings. Why dwellings, IDK. I mean we sleep at night in dwellings and is not a problem but most other places we don't sleep there but it is apparently a fire/smoke hazard if not in a dwelling??

Only thing I can think of is that it's a situation where in residential it'll be limited scope of wiring. A dwelling unit will be minimal wiring but a multifamily or commercial building could end up having tons of feeders and such run in a drop ceiling so allowing NM might create the potential for some problems. Other issue I can see is that residential is designed to get out of the building fast in a fire and multifamily and commercial you might have people in there for a longer time. Doesn't mean monstrosities of single family houses don't exist but there are less of them.

 

[kwired]

Only thing I can think of is that it's a situation where in residential it'll be limited scope of wiring. A dwelling unit will be minimal wiring but a multifamily or commercial building could end up having tons of feeders and such run in a drop ceiling so allowing NM might create the potential for some problems. Other issue I can see is that residential is designed to get out of the building fast in a fire and multifamily and commercial you might have people in there for a longer time. Doesn't mean monstrosities of single family houses don't exist but there are less of them.

Not the case around here where main panel is often in basement and all the circuits run in the floor joists to wherever is convenient to penetrate the first floor to get to the final destination. You pretty much have every single home run in at least a portion of said ceilings.

 

[ramsy]

Nope, MC or AC is fine.

Don't believe AC works outside, per 320.12(2)
MC, per 330.10(11) unless paint can be considered a corrosion resistant jacket

 

[roger]

Don't believe AC works outside, per 320.12(2)
MC, per 330.10(11) unless paint can be considered a corrosion resistant jacket

If the box is simply mounted on the exterior wall the assembly is not in a damp or wet location. If the assembly will travel a distance in a damp or wet location I would simply transition to another method at the point where it leaves the interior of the building.
With that said the OP would have the same issue trying to use FMC in a wet location.

 

[Fred B]

Don't believe AC works outside, per 320.12(2)
MC, per 330.10(11) unless paint can be considered a corrosion resistant jacket

Be careful as there is much if it being provided that is MC Lite, an Aluminum Sheath, it will corrode in contact with concrete. replaced a lot of it that someone had installed in contact with (*not in) concrete that the sheath had basically disappeared at every point it touched the concrete, less than ten years installed. Didn't look in code if there is limitations specifically related to this "MC Lite" and concrete contact.

 

[electrofelon]

Is possible to have occupancy where NM cables can be used, but NM cable is not allowed in suspended ceilings other than in dwellings. Why dwellings, IDK. I mean we sleep at night in dwellings and is not a problem but most other places we don't sleep there but it is apparently a fire/smoke hazard if not in a dwelling??

Massachusetts allows NM above drop ceilings in commercial occupancies. As you would expect, these places are burning down left and right.

 

[roger]

Didn't look in code if there is limitations specifically related to this "MC Lite" and concrete contact.

I'm not saying it's the best practice but, there is no prohibition for using MC lite in contact with concrete in the NEC. For further installation guidelines see UL categories (AALC) and (PJAC)

You could also use Al tubing or conduit in contact with concrete.

For added expense you could use a jacketed MC or AC such as "parking lot cable".

 

[rc/retired]

Massachusetts allows NM above drop ceilings in commercial occupancies. As you would expect, these places are burning down left and right.

Why are they burning down?

Ron

 

[infinity]

We install MC Lite in contact with concrete all of the time without issue. There would need to be some other factor (like a corrosive environment, water intrusion, etc.) involved for it to corrode.

 

[ActionDave]

Why are they burning down?

Ron

Everyone knows romex is the most deadliest wiring there is.