Romex and EMT in Attached Garage

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  #1  
Old 04-25-15, 03:39 PM
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Romex and EMT in Attached Garage

Hi again,

I have a question about running Romex in EMT in an attached garage for physical protection. I am wiring my attached garage, following the advice that I got in a this thread:

http://www.doityourself.com/forum/el...lt-garage.html

I now have a dual phase subpanel, and I need to wire outlets and lighting. The walls are finished, so I am planning to run EMT to external boxes. Could you guys help with these questions?

1. Is my attached and finished garage considered a wet location or dry? How do I know? The only garage outlet that came with the house is GFCI-protected.

2. Can I use Romex at all there? I have most of 500' roll of 14/2 and another one 500' of 12/2. I hope I do not need to explain to my wife why I need to buy more wire...

3. Can I run this Romex in EMT for physical protection? Internet gives me a lot of conflicting opinions on this.

Here's what I want to wire:
- 20A circuit for two outlet boxes on one wall, two dual receptacles each.
- Another 20A circuit, same as above, for the other wall.
- 15A circuit for 2 independently switched dual ceiling receptacles for lights, in one box on the ceiling. Two switches for them in one box on the wall next to the panel.


Thanks! Any other ideas and suggestions are also welcome!
 
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  #2  
Old 04-25-15, 04:26 PM
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I now have a dual phase subpanel
No such critter. Do you mean a 120/240 single phase subpanel?
Can I use Romex at all there?
Yes, but best practice if you use a continuous conduit system is to use individual conductors. NM-b run higher then 7'6" along a wall is usually considered protected so you could just run the NM-b along the wall with no conduit then use PVC or EMT conduit as a sleeve down to the receptacle or if there is an accessible attic and interior walls just run the NM-b behind the Sheetrock. If you use EMT not PVC: EMT even in a non continuous system needs to be grounded so boxes will need to be metal and you will need bushings where the cable enters the EMT.

Garage receptacles are best wired on 20 amp circuit using #12. They must be GFCI protected. Lighting can be 15 amps using #14 and (usually) does not need GFCI protection.
 

Last edited by ray2047; 04-25-15 at 05:44 PM.
  #3  
Old 04-25-15, 04:40 PM
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Ray has given you good advice. If you choose to use your type NM cable in conduit I would suggest no smaller than 3/4 inch for a single cable and no less than 1 inch for a maximum of two cables. You will need to pull both cables at the same time and also use a pulling lubricant.

Really, using individual conductors with type THHN/THWN insulation is the preferred way to go with conduit.

And yes, the garage is considered a dry location.
 
  #4  
Old 04-25-15, 07:25 PM
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Where are you located? You didn't complete your profile. In my area, the county will not allow a cable assembly in conduit except for a short length of conduit for physical protection. Bottom line is, they won't allow a complete run of conduit to have NM cable (aka romex) pulled into it. The NEC doesn't prohibit it, but as mentioned many times on this forum, all codes are local. Have you taken out your permit yet? Have you talked to the AHJ/inspector yet?
 
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Old 04-25-15, 08:40 PM
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O/P's location is Colorado.
 
  #6  
Old 04-25-15, 10:11 PM
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Thanks!

I live in Colorado, Douglas County.

I pulled the permit and spoke to the inspector but he did not ask, and it did not occur to me that that would be an issue. One would think that cable in conduit is safer than without one... Code is code though, I guess.

So, my options seem to be either to stick to the original plan and run romex in large enough conduit all the way, or just to use EMT for sleeves and hope that exposed NM above 7'6"" is ok. Or to get THHN wire in variety of colors... Is that about right? (All the walls and ceiling are drywalled and freshly painted, I am hoping to avoid opening them up.)

Another set of questions:

1. Can I run wire through the subpanel, e.g. a single wire from ceiling outlet into the panel, then from the panel to the switch, no connections in the panel?

2. Can I connect two wires in the panel using twist connector (basically, using the panel as a box)?

3. If I need to run more than one hot wire to the box, for example if I am wiring two independently switched outlets in the same box, can I use the same color of the wire for both, or it needs to be black and red? Basically, can I get away with buying just tree colors: white, black and green (for ground) or I need more colors?

Thanks!
 
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Old 04-25-15, 10:29 PM
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All the walls and ceiling are drywalled and freshly painted, I am hoping to avoid opening them up.
You don't need to tear up walls to run cable. If there ian unfinished attic above you won't probably even need to patch any drywall.
1. Can I run wire through the subpanel, e.g. a single wire from ceiling outlet into the panel, then from the panel to the switch, no connections in the panel?
No, you need two wires plus a ground and wires need to be in a raceway such as conduit. Do you mean cable?
2. Can I connect two wires in the panel using twist connector (basically, using the panel as a box)?
Yes splices can be made in the panel.

Grounded conductors (Neutrals) must be white ot gray.
Grounds must be green or (or bare if in cable). EMt can serve as ground.
Ungrounded conductor (hot) may be any color but white, gray, or green
 
  #8  
Old 04-25-15, 10:45 PM
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Thanks, that helps a lot!

So it seems that I only need to buy two rolls of wire, white and black, and I can run them in EMT.

One more question: in my panel, all the knockout holes are at the bottom and sides, while it would make more sense to me to run from the top. Can I just drill a hole there, or I can only use knockouts for connecting EMT?
 
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Old 04-25-15, 11:46 PM
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While the EMT is a code acceptable ground some electricians prefer to run a ground wire because EMT joints can be knocked apart over time. If you use existing knockouts and they are concentric or eccentric or washers are used you must use a grounding bushing jumpered to the ground bar of the panel or a ground screw if it is a metal junction box.

If the arrangement of your panel interior allows you can drill holes in top.
 
  #10  
Old 04-26-15, 01:30 AM
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Ray, eccentric knock-outs do NOT require the bonding bushing because a substantial amount of the connector will be in solid contact with the enclosure. That is why the eccentric knock-out was developed. Concentric knock-outs DO require the bonding bushing because the only contact to the enclosure is through the little tabs between the concentric knock-outs.

Croco, count me as one that ALWAYS runs a green equipment grounding conductor through EMT conduit rather than rely on the conduit couplers as a grounding medium. I've seen too many couplers pulled apart to even think of using the conduit as a ground.
 
  #11  
Old 04-26-15, 04:58 AM
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Just curious,if you have attic access why not use the NM-B cable you have and fish the walls and cut in old work boxes? I bet Wifie would be happy if you use the cable you already have.
Geo
 
  #12  
Old 04-26-15, 01:27 PM
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Once again, Ray, all - thanks!

To answer some questions: I do not have attic in the garage - kids' bedrooms are right above. The panel is on the firewall that separates the garage from the rest of the house. So, cutting into that is fairly constrained to the point that I do not want to mess with it due to fire code. An extra twist on all that is that the parts of the garage that share walls with the house (the firewall, the ceiling, and parts of the other walls) were drywalled before I moved in, so I do not know what's inside, and do not want to mess with.

So, my current plan, after all advice above, is this.

1. I am buying two rolls of 12-gauge THHN, white and red(black) and pull it through 1/2" EMT for the 20Amp receptacle circuits and for the 15A switched ceiling outlets for lighting.

2. I will put in GFCA receptacles as first in each of the two 20Amp circuits. No GFCA for the ceiling receptacle for lighting - can change later if it does not fly with the inspector.

3. I will use EMT as ground because all runs are short. I will add proper bonding bushings for knockouts (I have concentric ones). If this does not fly with the inspector, I am hoping I can pull additional grounding wires.

4. I am also adding a 50Amp 240V 6-50R receptacle. This one is right next to the panel, 2 feet, so I will use three 8-gauge THHN: two hot and one neutral, EMT for ground. I know that I do not need neutral for 6-50R but I may need it in future. This still seems to be within what fill conduit chart allows for 1/2EMT.


I try to let you guys know how it went, and if there are more comments and suggestions - please post them.
 
  #13  
Old 04-26-15, 01:50 PM
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Just a comment:
I also would run a separate ground through conduit. To me, I don't consider it cost prohibitive and it provides a more secure ground.
 
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