MC Cable - Conducter Ampacity

[mobiledynamics]

For Armoured MC cable - 8AWG to be more specific, does it fall into the 90 degree or 75 degree column by default. IE, NMB would make this 8AWG in the 60 degree column

 

[Charles (in GA)]

Since there are no devices such as switches and receptacles rated at 90°C then you will end up using the 75°C column to calculate amps. If the wire is 90°C rated then that would be used for derating purposes.

330.80 Ampacity. The ampacity of Type MC cable shall be determined in accordance with 310.15 or 310.60 for 14 AWG and larger conductors and in accordance with Table
402.5 for 18 AWG and 16 AWG conductors. The installation shall not exceed the temperature ratings of terminations and equipment.

 

[Norcal]

Armored (AC) and Metal Clad (MC) are two different materials covered by different NEC articles I mention this since the OP referred to "Armoured MC cable".
AC art 320
MC art 330

 

[mobiledynamics]

Derating aside, I always though 6 awg was for 50 amps...

I'm looking at a chart at it shows for 8 awg, 90 at 55 amps, and 75 at 50 amps

 

[alfredeneuman]

As it should be.
MC, AC, and individual conductors in conduit go by the 75° rating

NM, UF and SER cables buried in insulation must use the 60° column, #8AWG 40 amps and is #6AWG 55 Amps for copper

 

[wyliesdiesels]

Derating aside, I always though 6 awg was for 50 amps...

I'm looking at a chart at it shows for 8 awg, 90 at 55 amps, and 75 at 50 amps

Its not that simple or cut and dry. Depends on the type of wire, installation AND derating factors if any are required...90* c column is ONLY for derating!

 

[mobiledynamics]

http://www.encorewire.com/wp-content/uploads/EncoreWire-MC-PVC-AL.pdf
This is what I was referencing when I said the ~chart shows these ampacity ratings~


Here's the scoop. I plan to run a 50 amp for a electric car charger....
I already have some leftover 8/3 MC wire in my stash.

I also do have spools of 6 THHN, but if I can use up the 8/3 MC, I'd prefer to utilize this instead of the 6 wire.

Thoughts ?

 

[alfredeneuman]

Here's the scoop. I plan to run a 50 amp for a electric car charger....
I already have some leftover 8/3 MC wire in my stash.

I also do have spools of 6 THHN, but if I can use up the 8/3 MC, I'd prefer to utilize this instead of the 6 wire.

Thoughts ?

Do it

 

[wyliesdiesels]

http://www.encorewire.com/wp-content/uploads/EncoreWire-MC-PVC-AL.pdf
This is what I was referencing when I said the ~chart shows these ampacity ratings~


Here's the scoop. I plan to run a 50 amp for a electric car charger....
I already have some leftover 8/3 MC wire in my stash.

I also do have spools of 6 THHN, but if I can use up the 8/3 MC, I'd prefer to utilize this instead of the 6 wire.

Thoughts ?

Thats for PVC jacketed MC but the ampacity is the same.

How long is the run? If not extremely long, u should be fine!

 

[mobiledynamics]

The spot I want to locate the charger is aprox. 60 feet from the loadcenter.

 

[Charles (in GA)]

Here's the scoop. I plan to run a 50 amp for a electric car charger....
I already have some leftover 8/3 MC wire in my stash

What kind of charger are you installing? Most level 2 chargers do not require more than a 40 amp circuit (80% load of 32 amp, since this is a continuous load), as most plugable cars cannot handle more than that (with the exception of the Tesla and possibly a few others.

Just finished my wiring on my $399 GE DuraStation installation tonite.

Charles