Romex to THHN

[TravisT]

I'm getting ready to run a couple additional circuits in my garage, and have a question. My plan is to come out of my 200 Amp panel and run romex through the top of the panel, through the wall and up through a surface mount box. From there I'm planning to convert it to THHN and out via 3/4" EMT.

I may be overthinking it, but wanted to make sure this made sense. Seems like sometimes the simple things are what I get hung up on.


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[sberry]

Not a problem.

 

[wyliesdiesels]

No issue that i can think of.

What size circuit?

 

[TravisT]

My plan is at least two 20A circuits, a circuit for lights and one 220v run for my welder.


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[TravisT]

By code, the surface mount boxes should be attached to studs, correct? Also, the box I have doesn't have knock-outs in the back. I didn't realize this when I purchased it. Any problem with drilling a hole for the romex to enter the box? The box is about 6x6x4 with removable cover.


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[Garage Dog]

The box must have knock-outs on the sides you can use, but if needed you can drill your own hole. Just be sure to drill it a size that will accept a standard Romex connector ��

Attaching your box to a stud is a good way to secure your box, otherwise there are boxes called "remodel" boxes that have these little wings that pinch the Sheetrock to hold it in place which are allowable by code everywhere I know of.

Be safe, do you know what is hot in your breaker panel? If you have any doubts given your experience level, disconnect your main breaker when running wires and adding the new breakers.

Good Luck

GD

 

[TravisT]

I'm very comfortable working with power, and ultimately know what is safe and unsafe. I'll admit that I can't recite the NEC code book though. I want to make sure that I do this by code, as I want it to be safe.

With you not knowing my experience level, I appreciate the warnings.

I'll probably have a couple other questions along the way, and appreciate all the experienced GJers that offer help!


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[TravisT]

Oh, and to answer your question, the box does have knockouts on all sides, just not the back of the box. I just didn't realize it when I grabbed the box.


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[toplessHO]

the advantage of having EMT all the way is its easy to later add or modify circuits.
that said if you are stuck on using NM(romex) maybe add a couple more 12/3 for future.

 

[TravisT]

The garage is finished and the panel is in the wall, so I just need romex to get it to the surface. After that it's all surface mount EMT for the rest of the garage.

Edit: Unless there is a better way to do this than using NM from the panel to the surface mount box. That's what I'm trying to figure out. Any suggestions welcomed.

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[teamextreme]

That's the best way to do it. Make sure you bond the box with one of the ground wires from the romex to a ground screw in the box.

 

[wyliesdiesels]

Keep in mind if you run multiple individual conductors in pipe, derating factors come into play at 4 or more current carrying conductors.

For #12 THHN, unless u have 10 or more in the same pipe, then its inconsequential.

 

[Norcal]

Use aluminum or steel flexible conduit from the panel to the first box, then can forget about the Romex®.

 

[TravisT]

Keep in mind if you run multiple individual conductors in pipe, derating factors come into play at 4 or more current carrying conductors.

For #12 THHN, unless u have 10 or more in the same pipe, then its inconsequential.

I think I should be fine. I'm running 3/4" EMT, and there's only one point where I'll be running 3 circuits in one run. In this run, I will have 1 220v circuit and 2 120v (20A) circuits. If I'm tracking correctly, I'll need two hots and a neutral for the 120v circuits (#12), and two hots (#10) for the 220v. Although I know that you can use the conduit for a ground, I plan to run an additional #10 ground as well. I think I'm well within the limits without needs for derating, but I'll double check.

Use aluminum or steel flexible conduit from the panel to the first box, then can forget about the Romex®.

This is actually a possibility, because I'm low on knockouts on the top of my panel. There is a larger knockout (1" or 1 1/2" maybe) that would be perfect for some flex conduit and I could fish it through the wall. I may look into this.

 

[Fyrme]

1" and even more so 1 1/2" flex is not very "flexible" Without seeing your set up I can't say if it will work or not. You need to make sure there is plenty of room to use the flex. For example, if you are wanting to exit the wall in a perpendicular manner, then you need a minimum of aprox 6" space to bring a piece of 1" flex into the back of a box. If using 1 1/2", you can pretty much forget about it, unless its straight out of the panel into the box with no bends.

Again, without seeing your setup, since everything else is in EMT, why not get a bigger box and build a raceway from the panel to the box. This will give you way more future options. That is what I did in my shop. My panel is outside on the back wall. I ran a 2 1/2" ****** into a 8"Hx10"Wx4"D Jbox inside the shop. I then branched out with conduit and NM cable depending on where it went.

 

[LS6 Tommy]

If given a choice, I'll pull NM up a wall any day before MC...

Tommy

 

[Fyrme]

I'm not talking about MC Tommy, I'm talking about flexible conduit. It doesn't have any wires in it. 1/2" flex can have up to 6 current carrying conductors (so 7 wires), just like EMT, that you pull.

 

[wyliesdiesels]

What type of flex are u talking about?

metalic, non metalic, or water tight?

Metalic is FMC (brand name greenfield), non metalic is ENT(aka smurf tube; the blue stuff), or flexible liquid-tight???

1/2" FMC can have a total of 9 #12 THHN wires.

 

[Fyrme]

Metallic, yes greenfield if you want to use a old trade term. Sorry, my mind and background are always in 'commercial' mode, so it was assumed in my head. No need for liquid tight in this case, I don't believe. Smurf is only good for LV data imo.

 

[TravisT]

1" and even more so 1 1/2" flex is not very "flexible" Without seeing your set up I can't say if it will work or not. You need to make sure there is plenty of room to use the flex. For example, if you are wanting to exit the wall in a perpendicular manner, then you need a minimum of aprox 6" space to bring a piece of 1" flex into the back of a box. If using 1 1/2", you can pretty much forget about it, unless its straight out of the panel into the box with no bends.

Again, without seeing your setup, since everything else is in EMT, why not get a bigger box and build a raceway from the panel to the box. This will give you way more future options. That is what I did in my shop. My panel is outside on the back wall. I ran a 2 1/2" ****** into a 8"Hx10"Wx4"D Jbox inside the shop. I then branched out with conduit and NM cable depending on where it went.

So I'm just basing it off the knockout sizes I have in my panel. There are only a boule 1/2 or 3/4 left. That may not be enough to run all of my NM cable properly through them, since you can only run 2 max through each knockout with the right connectors. One of the 3/4" knockouts could handle all the circuits if I do it through flex conduit (greenlee) like you mention above. I don't think I'd even need to worry about the larger knockout in my panel. Hope this makes sense.

I'll post some pictures to make sure nothing's lost in translation.


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[Fyrme]

Yes, if you can make 3/4" metallic flex work, then by code you can pull 12 12awg current carrying conductors plus one 12awg ground through it. That is 6 circuits. It used to be more until they decided that every circuit needs it's own neutral now.

 

[AntonLargiader]

...until they decided that every circuit needs it's own neutral now.

In what context? Are multi-wire branches not allowed anywhere now, or just in this one? I've been reading up on them and haven't seen anything indicating that they were disallowed.

 

[wyliesdiesels]

Yes, if you can make 3/4" metallic flex work, then by code you can pull 12 12awg current carrying conductors plus one 12awg ground through it. That is 6 circuits. It used to be more until they decided that every circuit needs it's own neutral now.

Not sure what youre referring to unless youre speaking of AFCI and GFCI breakered circuits.

 

[Fyrme]

Ok, in all technicality, that's not 100% accurate, but since the NEC reads like a law book, things can be interpreted differently. We practice dedicated neutrals in the commercial industry where I'm from. So rather than tripping an unrelated branch circuit by using breaker ties, we dedicate a neutral to every branch circuit. I pulled this off of Mike Holt's forum...

In 210.4(B) it says:

"(B) Disconnecting Means. Each multiwire branch circuit
shall be provided with a means that will simultaneously
disconnect all ungrounded conductors at the point where
the branch circuit originates."

There's also an informational note that refers you to 240.15(B), which says:

"(1) Multiwire Branch Circuit. Individual single-pole circuit
breakers, with identified handle ties, shall be permitted
as the protection for each ungrounded conductor of multiwire
branch circuits that serve only single-phase line-to-neutral
loads."

But ask me how I wired my shop

 

[wyliesdiesels]

U can use a shared neutral between 2 opposite ungrounded conductors which is an MWBC.

Commercial and industrial is vastly different than residential.

 

[Fyrme]

Sorry Travis, I didn't mean to tech up your post to bad. I usually try and avoid the heavy details, but I was asked so I had to answer back. As far as the neutral deal goes, I wouldn't worry about that part to much. Millions of homes and shops and businesses in the US are wired with a single neutral feeding 1,2 and 3 branch circuits.

 

[wyliesdiesels]

Sorry Travis, I didn't mean to tech up your post to bad. I usually try and avoid the heavy details, but I was asked so I had to answer back. As far as the neutral deal goes, I wouldn't worry about that part to much. Millions of homes and shops and businesses in the US are wired with a single neutral feeding 1,2 and 3 branch circuits.

Not in my neck of the woods.

An MWBC is considered one branch circuit btw

 

[Fyrme]

U can use a shared neutral between 2 opposite ungrounded conductors which is an MWBC.

Commercial and industrial is vastly different than residential.

Residential is foreign to me, but that does make sense. Otherwise I guess they would be making 12/4 NM cable to be compliant or selling a **** ton of 20a two pole breakers, huh

 

[Fyrme]

Not in my neck of the woods.

An MWBC is considered one branch circuit btw

Well,,,you are in CA, the innovators of making laws to protect dumb humans from themselves. We didn't start the practice until the late 2000's so, you're telling me that CA has done this all along?

 

[rlitman]

What type of flex are u talking about?

metalic, non metalic, or water tight?

Metalic is FMC (brand name greenfield), non metalic is ENT(aka smurf tube; the blue stuff), or flexible liquid-tight???...

Flexible liquid-tight comes in metallic (LFMC), and non-metallic (LFNC), just to make things more confusing

... Smurf is only good for LV data imo.

Smurf offers the wires better protection than the jacket on Romex, which is sufficient in this case. If Romex is fine, so is smurf tube, though it does seem to make things unnecessarily complicated.

Though the thing I use smurf tube most for is sleeving to protect cords where they may drag on the floor in the shop. I've got pieces of it protecting the ground wire on my welder, and the cord to my table saw. I used to have it on my TIG torch cable too, but I've since hung that from the ceiling instead, with hooks that also hold my pedal's cable.

 

[wyliesdiesels]

Residential is foreign to me, but that does make sense. Otherwise I guess they would be making 12/4 NM cable to be compliant or selling a **** ton of 20a two pole breakers, huh

Actually southwire just recently started making cable just like that but its designated as 12/2-2. Its for use with AFCIs that DO require separate neutrals and the idea is to save on runs of 12/2 and labor.

Yes houses with multipe MWBC DO have multiple double pole or handle tied breakers. One circuit that is commonly done as a MWBC is the dishwasher/disposal circuit- one outlet under sink supplied with 12/3 NM-b.

Well,,,you are in CA, the innovators of making laws to protect dumb humans from themselves. We didn't start the practice until the late 2000's so, you're telling me that CA has done this all along?

Done what? MWBCs? yeah those have been used for decades. Guess its news to some.

Flexible liquid-tight comes in metallic (LFMC), and non-metallic (LFNC), just to make things more confusing



Smurf offers the wires better protection than the jacket on Romex, which is sufficient in this case. If Romex is fine, so is smurf tube, though it does seem to make things unnecessarily complicated.

Though the thing I use smurf tube most for is sleeving to protect cords where they may drag on the floor in the shop. I've got pieces of it protecting the ground wire on my welder, and the cord to my table saw. I used to have it on my TIG torch cable too, but I've since hung that from the ceiling instead, with hooks that also hold my pedal's cable.

Yes i know theres metallic and non metallic liquid tight. Didnt want to complicate things with that since the OP shouldnt need LFMC.

 

[Fyrme]

Actually southwire just recently started making cable just like that but its designated as 12/2-2. Its for use with AFCIs that DO require separate neutrals and the idea is to save on runs of 12/2 and labor.

Yes houses with multipe MWBC DO have multiple double pole or handle tied breakers. One circuit that is commonly done as a MWBC is the dishwasher/disposal circuit- one outlet under sink supplied with 12/3 NM-b.



Done what? MWBCs? yeah those have been used for decades. Guess its news to some.



Yes i know theres metallic and non metallic liquid tight. Didnt want to complicate things with that since the OP shouldnt need LFMC.

Ok, I think I was, or maybe we were both getting confused on the use of a dedicated neutral from a branch circuit run via raceway due to residential vs commercial applications. Yes, I am aware residential applications use 12/3 NM for branch ckt's. IMO, given the opportunity, every home run entering a panel should be 12/3 and branch off that at the first box. It would make for a cleaner prettier panel termination.
In a commercial application, which to me can include all or part of a residential shop or barn, that utilizes conduit as a raceway, it wasn't until the last 10 years or less that we pull dedicated neutrals. For example a 3ph service used to have one neutral for all three phases, allowing you to pull more branch circuits through a raceway than you can now with a one for one... Make sense?

OP, aren't you glad you asked?
And to think, this is the most I have EVER posted in this section in the 4 years I've been here.

 

[Norcal]

The one problem is if this is in a 2X4 wall 1/2" flex is barely going to make it, & it may or may not meet minimum bending radius requirements, another way would be use a 6X6X6 NEMA type 1 screw cover can in the wall w/EMT between the panel & can, then replace the drywall & finish it to match, the box will stand proud of the wall & a knockout punch (preferred), or a hole saw used to create a entry in the side for the surface mounted conduit. This does assume there is room in the wall cavity w/ the existing NM conductors, if there is not, it may be possible to do it below the panel.

 

[Fyrme]

The one problem is if this is in a 2X4 wall 1/2" flex is barely going to make it, & it may or may not meet minimum bending radius requirements, another way would be use a 6X6X6 NEMA type 1 screw cover can in the wall w/EMT between the panel & can, then replace the drywall & finish it to match, the box will stand proud of the wall & a knockout punch (preferred), or a hole saw used to create a entry in the side for the surface mounted conduit. This does assume there is room in the wall cavity w/ the existing NM conductors, if there is not, it may be possible to do it below the panel.

Correct.

 

[wyliesdiesels]

Ok, I think I was, or maybe we were both getting confused on the use of a dedicated neutral from a branch circuit run via raceway due to residential vs commercial applications. Yes, I am aware residential applications use 12/3 NM for branch ckt's. IMO, given the opportunity, every home run entering a panel should be 12/3 and branch off that at the first box. It would make for a cleaner prettier panel termination.
In a commercial application, which to me can include all or part of a residential shop or barn, that utilizes conduit as a raceway, it wasn't until the last 10 years or less that we pull dedicated neutrals. For example a 3ph service used to have one neutral for all three phases, allowing you to pull more branch circuits through a raceway than you can now with a one for one... Make sense?

OP, aren't you glad you asked?
And to think, this is the most I have EVER posted in this section in the 4 years I've been here.

Oh now i realize what youre talking about. U confused me when u said 3 branch circuits.

U can still share a neutral between 3 ungrounded conductors on a 3 phase system. But thats still considered a MWBC and one branch circuit NOT 3. It only works on 3 phase wye systems- either 208Y/120 or 480Y/277. U cant do that on a 240v delta system due to the stinger leg.

 

[AntonLargiader]

Yes, I am aware residential applications use 12/3 NM for branch ckt's. IMO, given the opportunity, every home run entering a panel should be 12/3 and branch off that at the first box. It would make for a cleaner prettier panel termination.

How does commercial differ? Reason I'm asking is that I need some receptacle circuits in my new commercial space and I was planning to do exactly as you said; run 12/3 from a recessed panel to THHN in EMT to the first receptacle (GFCI), then split the neutral so the GFCI controls the following four boxes and then the original neutral does the same thing for the second four boxes. Seems that would meet the GFCI requirement. Or just use a GFCI 2-pole breaker.

Looking around, it seems this post describes it pretty well:
http://forums.mikeholt.com/showthread.php?t=135212&p=1296062#post1296062

 

[wyliesdiesels]

How does commercial differ? Reason I'm asking is that I need some receptacle circuits in my new commercial space and I was planning to do exactly as you said; run 12/3 from a recessed panel to THHN in EMT to the first receptacle (GFCI), then split the neutral so the GFCI controls the following four boxes and then the original neutral does the same thing for the second four boxes. Seems that would meet the GFCI requirement. Or just use a GFCI 2-pole breaker.

Looking around, it seems this post describes it pretty well:
http://forums.mikeholt.com/showthread.php?t=135212&p=1296062#post1296062

If u plan on using GFCI outlets before the neutral split then thats fine but u will need to run separate neutrals AFTER the GFCI.

A 2 pole GFCI breaker will negate the need for separate neutrals.

 

[AntonLargiader]

I don't quite follow you. Having an unmolested neutral for the second set of receps seems to tell me that it needs to split before the GFCI so it's behaving as two branch circuits. Also, it seems to me that splitting the neutral there negates the need to pigtail the neutral at each recep because removing a device cannot break the neutral for the other leg. We're only talking 30 feet of extra neutral. Two 15-foot workstations on one leg and general convenience outlets after that.

I may just get that GFCI breaker but if splitting the neutral saves me some pigtailing then I'll do it anyway.

OP: sorry for the hijack but the shared neutral thing seems pertinent to your question regarding conduit stuffing.

 

[TravisT]

OP: sorry for the hijack but the shared neutral thing seems pertinent to your question regarding conduit stuffing.

No worries, it seems these things have many interpretations. I'm following along, and will hopefully post some pictures up tomorrow.

For the record, because I'm running 1 - 30A 220v circuit and 3 - 20A 120v circuits. That's 6 #12s and 2 #10s (worst case) plus a ground. Best case, I think all I would need is the 2 #10s, 2 #12s (lights) and 3 #12s (20A circuits) (Edit: plus ground). I could easily drop my lights down to a 15A circuit.

If I'm tracking, even the worst case doesn't exceed the fill ratio for the 3/4" flex. Once I get to the j-box that is surface mounted, I'll be golden.

 

[sberry]

I don't quite follow you. Having an unmolested neutral for the second set of receps seems to tell me that it needs to split before the GFCI so it's behaving as two branch circuits. Also, it seems to me that splitting the neutral there negates the need to pigtail the neutral at each recep because removing a device cannot break the neutral for the other leg. We're only talking 30 feet of extra neutral. Two 15-foot workstations on one leg and general convenience outlets after that.

I may just get that GFCI breaker but if splitting the neutral saves me some pigtailing then I'll do it anyway.

OP: sorry for the hijack but the shared neutral thing seems pertinent to your question regarding conduit stuffing.

Its late but I think you got it right, you must have misunderstood him.