MC 10/12c

[Piramyd]

Hi
I am trying to understand how use MC #10 12C or #12 8C.
How Should manage the neutral wire when my branch circuits doesn't follow
a pattern like 1,3,5 or 12,14,16 etc. ?
I'm trying to reduce the installation cost for a warehouse. There are offices that I am planning to do as usual with MC 12/2 or 10/2 depend on the load and distance to the panels which are very far from offices inside the warehouse. I am avoiding to use EMT and THHN, on steel beam.
So that to run branch circuit to the panels, I intend to use MC 12c or 8c conductor.
I would appreciate some help on that.

 

[infinity]

Just remember that derating factors will apply to the cable when you exceed 3 CCC's in the cable. Personally I would use EMT and forget about the MC cable at least for the home runs to a certain location where you can branch off.

 

[JFletcher]

Without knowing more about the installation... Are your panels single phase or 3-phase? What kind of distances and loads are we taking about here?

If all of the offices are close together to each other yet far away from the panel you need to pull power from, I would tend to run ENT and a feeder to a sub panel in the office area, then pull more 'standard' branch circuits or multiwire branch circuit from there.

multiwire branch circuits are a great idea to save on the time and labor cost, however with my limited working with super MC, there are very few applications where I would choose to run it over ENT and THHN.

 

[Piramyd]

Thank for your answer.
Yes, I would need to de rate.
I just trying to cut cost using those wire.
But just to learn, can you expand the reason you would reject using that type of wire,
in this case for a warehouse where the terminate at panels' circuit breaker?

 

[ActionDave]

Thank for your answer.
Yes, I would need to de rate.
I just trying to cut cost using those wire.
But just to learn, can you expand the reason you would reject using that type of wire,
in this case for a warehouse where the terminate at panels' circuit breaker?

With 12AWG THHN you can pull six multi wire branch circuits in a 1/2" emt and go for several hundred feet before branching out with MC. Don't forget that voltage drop is load dependent and almost anything made that uses electricity can work fine with ten percent voltage drop so up sizing the home runs to 10AWG is often not needed.

 

[JFletcher]

Thank for your answer.
Yes, I would need to de rate.
I just trying to cut cost using those wire.
But just to learn, can you expand the reason you would reject using that type of wire,
in this case for a warehouse where the terminate at panels' circuit breaker?

12 conductor number 10 and 8 conductor number 12 would both be de-rated so that either cable would still be suitable for a 20 amp circuit.

If you pull a 4-wire feeder from your main 3ph panel to a subpanel in your office area, it could be number 6 or number 4 (or larger), you only need one breaker space in the main panel versus three or four, there is no derating over an 8 to 12 conductor cable, you have more downstream capacity available for later additions, etc.

Personally, the only times I have used super MC is with a long, convoluted pull where EMT was just not possible, and when pulling multiple runs of MC cable was less desirable than pulling one.

 

[kwired]

12 conductor number 10 and 8 conductor number 12 would both be de-rated so that either cable would still be suitable for a 20 amp circuit.

If you pull a 4-wire feeder from your main 3ph panel to a subpanel in your office area, it could be number 6 or number 4 (or larger), you only need one breaker space in the main panel versus three or four, there is no derating over an 8 to 12 conductor cable, you have more downstream capacity available for later additions, etc.

Personally, the only times I have used super MC is with a long, convoluted pull where EMT was just not possible, and when pulling multiple runs of MC cable was less desirable than pulling one.

With 12 conductor cable you could have 9 hots, 3 neutrals three phase or 8 hots, 4 neutrals single phase - if the neutrals are not carrying a high non linear load on the three phase systems they don't count as CCC's. This still leaves you in the 70% adjustment range and with 90C conductors you wouldn't need to upsize conductors for adjustment purposes.

 

[kwired]

Hi
I am trying to understand how use MC #10 12C or #12 8C.
How Should manage the neutral wire when my branch circuits doesn't follow
a pattern like 1,3,5 or 12,14,16 etc. ?
I'm trying to reduce the installation cost for a warehouse. There are offices that I am planning to do as usual with MC 12/2 or 10/2 depend on the load and distance to the panels which are very far from offices inside the warehouse. I am avoiding to use EMT and THHN, on steel beam.
So that to run branch circuit to the panels, I intend to use MC 12c or 8c conductor.
I would appreciate some help on that.

Presuming you are using MWBC's you don't have much choice, you must use three adjacent breakers and a common trip or handle ties for each MWBC. If adding circuits and you don't have such open positions in the panel you are going to have to re-arrange things to get adjacent spaces free for use.