MC Inside EMT?

[adelle]

Can MC be run inside EMT for 10 feet or less? I need to bring MC into an electrical room but don't want MC crawling up the wall. Looks tacky against all the neatly installed EMT.

Of course one could put a splice box in the ceiling but running the MC through an EMT stub is easier and mre reliable due to one less splice.

 

[Dennis Alwon]

Read art. 330.10(A)(7). The answer is yes-- in any raceway mc is permitted.

 

[B-Sass]

You will need a way to terminate the MC "jacketing" ...set screw connector on the emt, coupling and then mc cable connector in to the coupling. Strip the MC to lenght and install.

 

[adelle]

You will need a way to terminate the MC "jacketing" ...set screw connector on the emt, coupling and then mc cable connector in to the coupling. Strip the MC to lenght and install.

Ahh, similar to flex into EMT. I assume the wires inside MC are THHN. They seen to be.

 

[mcclary's electrical]

You will need a way to terminate the MC "jacketing" ...set screw connector on the emt, coupling and then mc cable connector in to the coupling. Strip the MC to lenght and install.

They make a fitting specifically for this, but keep in mind, the fitting must be accessible to be used in this manner of transition.

 

[Dennis Alwon]

If 330.10(A)(7) allows MC in any raceway then why would they allow that if the termination was necessary. I tend to agree that the jacket needs to be grounded but that is not what the section states.

 

[jeremysterling]

If 330.10(A)(7) allows MC in any raceway then why would they allow that if the termination was necessary. I tend to agree that the jacket needs to be grounded but that is not what the section states.

You will find the section that requires grounding in 300.10. That section mentions cable "armor". Technically, MC is surrounded by a metal "sheath", not armor, so you may be able to argue your way out of this requirement.

You may also consider 300.18. That section requires a "complete run" of raceway. The code does not mention specifically, but it does not exclude, the sheath of the MC being a "raceway." IMO, the sheath is a "raceway" and requires a terminal fitting.

There is an ongoing debate over the listing of rigid couplings and their usage in "changeovers". Some say that some AHJ will disallow the install. I have not seen that and I live in a city that has ridiculously stringent requirements for MC installs (including monthly calibration of your rotosplit):roll:

As was mentioned earlier there is Arlington, who makes fittings that work on 99% of the MC out there. (I have installed some feeder MC that Arlington products would not fit.) If they have a specific fitting for changing over, I would happily use it.

 

[jaylectricity]

You will need a way to terminate the MC "jacketing" ...set screw connector on the emt, coupling and then mc cable connector in to the coupling. Strip the MC to lenght and install.

Then does that still count as putting the MC inside the EMT?

 

[Split Bolt]

Then does that still count as putting the MC inside the EMT?

That's what I was thinking. That would be MC changing over to EMT, then back to MC again! That is not running MC in EMT at all!:-?

 

[Dennis Alwon]

You will find the section that requires grounding in 300.10. That section mentions cable "armor". Technically, MC is surrounded by a metal "sheath", not armor, so you may be able to argue your way out of this requirement.

If this is a sleeve then the cable armour could be grounded at the other end.

You may also consider 300.18. That section requires a "complete run" of raceway. The code does not mention specifically, but it does not exclude, the sheath of the MC being a "raceway." IMO, the sheath is a "raceway" and requires a terminal fitting.

If emt were installed as a complete raceway then the emt is the raceway and mc is just a cable inside the raceway.

As was mentioned earlier there is Arlington, who makes fittings that work on 99% of the MC out there. (I have installed some feeder MC that Arlington products would not fit.) If they have a specific fitting for changing over, I would happily use it

I realize there are fittings as well as home made fittings using a connector for the emt then a threaded coupling with an mc fitting on that. This does not answer the question I was asking about the meaning of the section I quoted. Can we really have a complete raceway and install mc inside????? Not sure why someone would do this but....

 

[dicklaxt]

I have been running MC(industrial setting) in rigid for years ,it was used as support and mechanical protection of the cable as it dropped from a cable tray to the user(jbox,mtr etc.),just remember to size the conduit per 53% fill or quick rule of thimb 1 inch larger than the MC outside diameter.The cable was grounded at the substation end,one more thing, we limited this conduit run to 30 feet with a max of 2-90 degree bends.

dick

 

[petersonra]

How is this any different than putting a piece of iron water pipe through a wall as a sleeve? The pipe is not a raceway anymore than the EMT is in this case.

There is no requirement that you treat the EMT as a raceway when it is not being used as one.

 

[renosteinke]

I think we're confusing ourselves a bit here ...

For the sake of argument, let's assume that you need to run some wires through a wall that is already completely filled with spray foam insulation - for example, to add a switch to the wall of a walk-in cooler.

Were you to do that, you would simply (yea, I know .. it sounds simple, but is a real PITA to actually do!) bore a channel in the insulation, then pull your cable throught the channel you created.

In that situation, you would only concern yourself with whether the hole was big enough for the cable .... you would not concern yourself with 'cable fill' requirements. You'd be delighted if there was already a 3/4" chase for your 5/8"OD cable.

I believe that the same principle applies here. A sleeve is just a sleeve. With the MC cable's sheath left intact, I do not see any need for the sleeve to be bonded, or for the sleeve to be any particular size. Nor, for that matter, need you use any 'approved' material; the sleeve can be copper tubing, square aluminum tubing, even a routed-out piece of wood.

With the EMT used as a sheath, it's not a wiring method; it's just a handy piece of pipe.

 

[Dennis Alwon]

Many are missing my point. The section cites that mc is good inside a raceway, it does not state used as a sleeeve, - I understand that a sleeve is not an issue but what about an entire raceway run of emt, for instance. I cannot see how that would be compliant but it seems to be what the code states.

 

[adelle]

How about Romex then?

How about Romex then?

I thought Romex in EMT was illegal? If the EMT is just a sleeve then can Romex be pulled through it?

I did this at home in the garage just to get the surface box wiring up to the garage attic, but of course it was not permitted or inspected! In my case here I do see an issue in that the Romex is not secured or clamped to the box, just the last staple before it enters the EMT. This can't be acceptable?

 

[al hildenbrand]

I thought Romex in EMT was illegal? If the EMT is just a sleeve then can Romex be pulled through it?

Get your Code book out and take a look at 334.15(B) & (C).

 

[al hildenbrand]

Many are missing my point. The section cites that mc is good inside a raceway, it does not state used as a sleeeve, - I understand that a sleeve is not an issue but what about an entire raceway run of emt, for instance.

330.10 Uses Permitted.
(A) General Uses. Type MC cable shall be permitted as follows:
.
.
(7) In any raceway

There is no qualification.

I have to wonder at the means of terminating the sheath of the MC so that the conductors may emerge. . . but that is a different issue than whether the run of MC is within a raceway, or not.

Also, it occurs to me to remember that "raceway" is defined in Article 100.

 

[Dennis Alwon]

I thought Romex in EMT was illegal? If the EMT is just a sleeve then can Romex be pulled through it?

I did this at home in the garage just to get the surface box wiring up to the garage attic, but of course it was not permitted or inspected! In my case here I do see an issue in that the Romex is not secured or clamped to the box, just the last staple before it enters the EMT. This can't be acceptable?

As a complete raceway, as Al stated, nm is allowed but fill must be considered. If the raceway is on the exterior of the house then nm would not be allowed as the conductors in nm are not wet location rated.

There are scenarios where a piece of pipe may be used out of the top of panel and NM may be inside but there are restrctions. Look at art. 312.5(C)

 

[Dennis Alwon]

I have to wonder at the means of terminating the sheath of the MC so that the conductors may emerge. . . but that is a different issue than whether the run of MC is within a raceway, or not.

So how would you terminate the sheath- I would assume it would have to be done so the section is not quit accurate unless I am missing something.

 

[dicklaxt]

Here's what I did,the MC was routed inside of the sleeve and slack looped at the bottom to a fixed conduit fitting where the MC cable was terminated and entered the fitting,MC,all jackets etc were stripped back and conductors carried on in a closed conduit system to user.

dick