Sign In to join the community | Help

cable connectin

is there any, code compliant, way to connect mc cable to Romex without using a junction box?bmc

Not what you were looking for ? Try posting a question
Posted 2013-11-16T18:01:00+0000  by bmc bmc

Hey bmc,


Thanks for your question and welcome to the community!


The only 2 items I can think of to possibly make this work are shown below....if they meet criteria.


Up until this product was sold in our stores about 2 years ago, we never carried anything to connect Romex cables together. This is the only thing that I'm aware of to connect Romex to Romex...but it unfortunately isn't code if you plan to connect it for MC to Romex.


It is however, it compliant to NEC approved Article 334-40b.


That's not to say such a connection exists. I've been in the industry about 14 years, and the only thing I've seen that connects different types of wire/conduit is EMT conduit to Romex (non-metallic).

However, since you have metal-clad cable, this wouldn't exactly be code. And, that's not to say a connector exists for you.


Typically though, almost all electricians I've seen in this situation just bite the bullet and use a small handy box with a blank cover alongside the MC connectors and NM connectors to safely cover the connection.

1-Gang Handy Box - Silver

Please let me know your progress on this, and let me know if you have any further questions,


Posted 2013-11-16T18:24:27+0000  by Joseph_HD_ATL

Thanks silver

first a little context. I am in the process of installing under cabinet LED lighting. The fixture l am removing has a short length of mc cable which connects to the old unit via an mc cable clamp. Unfortunately the mc cable cannot be pulled any further out of the wall to reach the input connector on the unit to be installed. Furthermore this unit requires an nm cable input.  Although l can configure a junction box to make the mc to nm transition the junction box takes up space l want to use for installing the new unit; also it doesn't look good.

Your first and second potential solutions are really helpful. The first was exactly what l was thinking might exist somewhere out there albeit for an mc to nm connection. I guess also that the conductors are a push fit into the connector??

If l were to connect an mc cable to one side l don't believe strain relief to be an issue as the environment does not involve any cable movement. Nevertheless l am not sure an inspector would approve. Maybe l should ask!

Likewise the barrel connector, your second solution. Again if l were to use this method are the mc and nm conductors butt spliced and contained within the barrel.

Sorry to be so wordy


Posted 2013-11-16T19:25:21+0000  by bmc

You are welcome. name is actually Joseph, silver is the level I'm on on you are Foundation.


I'm glad you explained your situation in more detail, it helps wrap my mind around what you are encountering.


If this is going to be inspected, you'll need to have everything to code. In fact, if it is, I would recommend talking to the inspecter or a local electrician to see what can and can't work. In other words, I'd hate for you to use the items shown above and not have them work.


I've never seen a fixture that requires just an NM input for connection purposes. Even if that is the case, you could extend the MC with more cable, using a coupling shown below. This would at least get the MC closer to the fixture.

Once you get the MC closer, you can then check to see if such a MC to NM connector is out there. I personally haven't seen any of anything permanent at my stores short of what I've already shown to you.


I also know that they do make shallow contact boxes. Typically though, these are in PVC and won't be code vs. using metal (MC needs to go into metal boxes).


Do you think that the coupling above with more MC extended could assist? Let me know, and we can go from there.




Posted 2013-11-16T19:48:47+0000  by Joseph_HD_ATL

There is no "connector" that allows you to joint NM-B and MC cables.  You'd need to make a splice in an accessible junction box.  You CAN NOT butt splice NM-B and MC.  Box clamps are also not optional.


I'm also wondering why you have MC cable in the wall.  In jurisdictions that would allow the use of NM-B cable, most people would use NM-B because it's generally cheaper and easier to work with.  That's not to say whomever wired these lights didn't happen to have some "extra" MC around and just used that.  The question, though, is if your jurisdiction allows the use of NM-B cable.


If you want to keep things neat, I might suggest Wiremold.  Place a Wiremold junction box on the underside of the cabinet by the wall.  Bring your existing MC cable into that.  Then use Wiremold raceway to run to your light fixtures.  Wiremold makes a connector that allows you to transition from the raceway to the round hole on a fixture.  You can even paint the Wiremold to match the cabinet color to help disguise it.



Posted 2013-11-16T21:26:25+0000  by Adam444

thanks Adam and Joseph - great info

there is one more configuration l should have mentioned but forgot. It might make the job easier - or not. The unit l am thinking of installing has an option to connect an AC line cord as opposed to the hard line connection we have been discussing. This would mean terminating the mc cable with a female 3 pin socket. I mention this as l found BRYANT make under cabinet power distribution boxes. It may be l can bring the mc into one of their  boxes. Also they look pretty nice.

Nevertheless l think l will discuss the barrel option Joseph and the wiremold option Adam with an inspector. However l had not planned on having the installation inspected.

Question, in both cases how would you recommend l join the 3 wires in the existing mc cable to the 3 wires in the nm cable that runs to the unit

Posted 2013-11-16T23:22:02+0000  by bmc

I'd say that if you can, using the Wiremold option that Adam suggested would be the best and more streamlined look for you.


I say this (and I forgot about it until Adam mentioned the name), is that Wiremold has very slim metal trims that hide wire.......and they have an end feed that would be essentially a very tiny junction box. Click on the one below to view more info on it.


It simply snaps in the Wiremold and the knockouts provided can work for your MC cable.


This is essentially the smallest 'junction box' that The Home Depot sells. If it were me in this situation, I'd bring the MC over to this, and then run Wiremold the rest of the way. You can place NM cable in it so it gives you a nice clean look.


I'm not aware of the Bryant distribuation boxes you speak of, but I've seen this option above work nicely.


Since you aren't going to have it inspected, it would still suffice and be safe as well with the option above.



Posted 2013-11-16T23:29:47+0000  by Joseph_HD_ATL

Going the route of plug-in fixtures is certainly an option (LeGrand makes a similar product).  Remember if you take a fixture designed to be hardwired and convert it, you're going to void the UL listing.  That's not really a big deal unless you plan on selling the fixture but you do want to make the conversion safely.  If the fixture requires a ground, then you need to use a three wire cable.  You'll also need to provide some kind of stain relief or bushing where the cable enters the fixture.


As for connecting MC to NM-B, there is only one option - an accessible junction box.  It looks like you could bring your MC into the Bryant product and then plug your lights into there.



Posted 2013-11-17T17:54:14+0000  by Adam444

Looks like l have two solutions; the Bryant box and the Wiremold. I like the latter as it "neatens up" the installation. Nevertheless l wil checkout each before l decide.

Thanks again guys for all your help; it really helps to talk with people who know whats out there and what the rules are


Posted 2013-11-17T21:34:45+0000  by bmc
Not what you were looking for ? Try posting a question