Can I zip tie MC armored cable to existing EMT in a garage, exposed run, against Code?
Hi.
Can I zip tie MC armored cable to existing EMT in a garage, exposed run?
The existing EMT has 120V 15 amp going to an existing outlet.
The proposed MC armored cable is 12/2 for a 220V 20 Amp circuit I’d like to run to one outlet for my bandsaw.
What does code say about doing that? I’m in southeastern PA, Bucks county.
Thanks.
Replies
MC is supposed to not be in exposed locations. It's typically the commercial version of romex. You usually see it in metal stud walls and in the plenum of commercial buildings, since the sheath/jacket doesn't burn like romex and give off toxic fumes.
But you're in luck. Conduit was designed for applications like these. You should be able to get 3x circuits (or 6x if you're doing multiwire but good luck with pulling that) into EMT without having to upsize your 15amp's wire size.
Check your tables and learn how to do derating (the last 2 licensed electricians I had were clearly a bit hazy on the topic along with multiwire circuits). With 14g and 12g wire you have some buffer (12g is actually rated for 30a, but you can never run 30a continuously on it. That gives you extra when you start derating for conduit). You also have to derate for voltage drop and hot locations. If you look in a typically commercial panel, they're often running 10g everywhere for all the 20A outlets to derate in large raceways. Also check your tables for conduit fill, but they're usually high than you can practically pull.
But offhand I'd guess pulling 3 additional THHN2 12gauge red/black/white wires through the existing conduit would probably get you there. Running a neutral even if you don't use it right away is a good thing to do (you can put all 3 plus ground onto a NEMA L14-20 or 14-20 receptacle). Also check the ground path. Ground wire isn't required in conduit (the conduit is the ground), but you have to make sure every connection going back to the box is tight). I like to pull a separate green ground through the conduit (ground doesn't count for derating, but does count for conduit fill). Ground can be shared between circuits, but neutral CAN'T unless it's multiwire and there are certain rules for it.
Other than that, you need to get some EMT couplers and connectors (and learn to bend conduit...but you can buy the prebent pieces and just use more couplers)
Thanks for that response. I know that in my area running exposed MC armored 12/2 is OK and allowed in my garage. All I need to know the answer to is..... Can I attach my MC cable to the existing EMT in my garage with zip ties? Meaning attached to and running along side the EMT. On the outside of the EMT. Yes or no?
The walls of my garage are bare meaning there is no drywall or interior sheathing. All existing outlets and lighting circuits are ran using EMT and it is all exposed. I don't know how to be more descriptive here.
I am not pulling wires thru anything, it's not necessary.
if your wire staples meaning zip ties? I personally pull the old staples out, run whatev, and put them back. Code is every 6" where I'm at. Outdoors is another thing, either bury it or something I'd imagine.