Sleeving MC Cable

Little Bill

Little Bill

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Semi-Retired Electrician
Is is permissible to sleeve MC cable with EMT? Such as running MC overhead and sleeving it down the wall to a box.

Also, what does this mean?

330.108 Equipment Grounding Conductor. Where Type MC
cable is used to provide an equipment grounding conductor, it
shall comply with 250.118(10) and 250.122.
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Sure, as long as you use an MC connector at the box and end the EMT at or just before it.

250.118(10) and 250.122 just talks about the EGC provided by the MC cable.

-Hal
 
EMT to MC fitting would be the best way to go.
 

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Little Bill said:
If the MC has an EGC in it, why would you use the MC as an EGC?
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You don't. The armor of MC is not supposed to be used as an EGC.
acrwc10 said:
EMT to MC fitting would be the best way to go.
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Yes, you could strip the armor where it enters the EMT and use that fitting. Then run the conductors down through the EMT. More work I suppose. I actually prefer to do it that way especially if there are bends.

-Hal
 
hbiss said:
You don't. The armor of MC is not supposed to be used as an EGC.
Click to expand...
According to 250.118 it can with stipulations. It doesn't make sense to need to use as an EGC when it contains an EGC.

250.118 Types of Equipment Grounding Conductors.
10) Type MC cable that provides an effective ground-fault
current path in accordance with one or more of the
following:
a. It contains an insulated or uninsulated equipment
grounding conductor in compliance with
250.118(1).
b. The combined metallic sheath and uninsulated
equipment grounding/bonding conductor of interlocked
metal tape–type MC cable that is listed and
identified as an equipment grounding conductor
c. The metallic sheath or the combined metallic sheath
and equipment grounding conductors of the smooth
or corrugated tube-type MC cable that is listed and
identified as an equipment grounding conductor
 
Any MC that you are likely to find will be either (a) (green insulated EGC along with the other conductors) or (b) that has a large (like #12) bare aluminum conductor just under the armor. You just cut that off at the end of the armor, the connector takes care of the bonding. While the latter is a labor saver, I don't like it at all as it goes back to relying in the connectors like the old BX and AC cable did. I would much rather make up solid connections using the green EGC like you do with the Romex bare EGC. Pigtail to the box and splice to all other EGCs in the box.

I should add that in any case, the armor of all MC cable must be bonded and that gets done by the connector to the metallic box and/or the bare EGC under the armor. And no, you cannot use PVC boxes with MC or AC cables unless you want to look like a hack. 🤯

-Hal
 
Little Bill said:
Is is permissible to sleeve MC cable with EMT? Such as running MC overhead and sleeving it down the wall to a box.

Also, what does this mean?
Click to expand...
I think we need to establish whether you are talking about "transitioning" or "sleeving"🤔. Transitioning would be stripping the cable and using A fitting or some combination of fittings that connects the cable to the EMT. It's a free country, you can absolutely transition. Sleeving, I'm not sure offhand.
 
All these approaches seem like ugly hacks. Why not just use a conduit body, terminate the MC at the conduit body, and run THHN down the EMT into the final box?
 
If you have the time and money, use a transition fitting. (My preferred especially commercial.) But the time-honored way of feeding a surface mounted box with MC, AC or Romex is to just sleeve it down the wall to the box. Put a connector on the box a couple of straps on the EMT and call it a day. Bob's your uncle.

-Hal
 
No one has explained why you would use MC as an EGC, or consider it an EGC, when it already contains an EGC. I'm not talking about bonding the armor, I'm just asking why would you consider the MC an EGC?
 
Little Bill said:
No one has explained why you would use MC as an EGC, or consider it an EGC, when it already contains an EGC. I'm not talking about bonding the armor, I'm just asking why would you consider the MC an EGC?
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When you re-identify the green and use it as a current carrying conductor...

Seen it several times. :eek:

Real answer is you are not allowed to.

-Hal
 
hbiss said:
Sure, as long as you use an MC connector at the box and end the EMT at or just before it.

250.118(10) and 250.122 just talks about the EGC provided by the MC cable.

-Hal
Click to expand...
Also MC fitting required per 300.11.
 
@Little Bill

We have all seen the "regular MC" that contains a green EGC. From what I understand the armor on that type of cable (weather aluminum or steel) is not considered and EGC even though it is bonded to the box the same as FMC or AC cable.

I can only guess the way the code is written is that there are some types of MC (which I have never seen) where the armor is approved for use as an EGC
 
Eddie702 said:
@Little Bill

We have all seen the "regular MC" that contains a green EGC. From what I understand the armor on that type of cable (weather aluminum or steel) is not considered and EGC even though it is bonded to the box the same as FMC or AC cable.

I can only guess the way the code is written is that there are some types of MC (which I have never seen) where the armor is approved for use as an EGC
Click to expand...
Maybe something like MCAP cable?

MCAP® Type MC All Purpose​

14 AWG through 8 AWG Copper THHN Insulated Conductors. Full-Sized Aluminum Equipment Grounding/ Bonding Conductor. UL Listed. 600 Volt. Rated VW1. Lightweight Aluminum Interlocked Armor is Part of Equipment Bonding/Grounding Path.​


Contact Us
 
hbiss said:
(b) that has a large (like #12) bare aluminum conductor just under the armor. You just cut that off at the end of the armor, the connector takes care of the bonding. While the latter is a labor saver, I don't like it at all as it goes back to relying in the connectors like the old BX and AC cable did.
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Yes, MCAP. Couldn't think of the name. Anything that sacrifices safety for saving labor is garbage AFAIC. I said why above.

-Hal
 
marmathsen said:
how do you properly connect the MC if the EMT is also connected to the box?
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The EMT is not connected to the box. The stripped end of the MC with the EMT slid over it is connected to the box with an MC connector. The EMT is then slid down as far as it will go to the MC connector and then strapped to the wall. Make it nice by bending an offset in the EMT just above the MC connecter.

-Hal
 
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