EMT capacity, Wire type, outdoor to indoor

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Old 08-28-15, 09:25 PM
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EMT capacity, Wire type, outdoor to indoor

Hello all, I'm new to the forums and new to home ownership - trying to hire an electrician to run power to a jacuzzi and possibly a jacuzzi heater (each requiring a dedicated circuit). The home was handed over to us with the tub inoperable and apparently rigged for inspection, but that doesn't really matter anymore.

I've already had electricians visit, and have been told different things regarding what's possible and what's allowed, with each contradicting the other, hence I'm here.

The facts:
-We need at least one 15-amp line for the jacuzzi motor (though a #12 20-amp line may be smarter to be "future-proof"?)
-We may opt for a 2nd 15-amp (or 20-amp) line for a heater for the tub, though a heater is not yet installed.
-With our finished basement and the tub being two floors above there is no good in-wall route - at least part of the run must be in outdoor conduit

One electrician proposed running EMT conduit down from the outdoor breaker box, along the foundation about 4" above ground (a concrete patio) before heading up the exterior wall and entering the home below the tub (there's an overhang where the tub is).

The next electrician proposed running EMT conduit up from the box, running it under our deck the opposite direction, heading up a corner of the home beside a gutter, then penetrating into the attic and going the full length of the house to the master bath where the tub is located.

Each says what the other proposes is not not allowed.

One said that the run along the foundation is not permitted. He said it must be at least 12" above the ground (rain/snow) when I asked about this possibility.

They also disagreed about the type of wire that must be used. When I mentioned possibly running two 15-amp (or 20-amp) lines in the same conduit one told me that we would have to switch to Romex instead of THHN. The other said we'd use THHN the whole way and Romex is not allowed (for both outdoor use and/or inconduit, so a double-whammy there).

So what are the correct answers?
1) Are two THHN circuits allowed within the same 1/2" EMT conduit?
2) Are two Romex circiuts allowed within the same 1/2" EMT conduit?
3) OR, is neither correct and a different type of wire required?
4) Can an EMT conduit not be run a few inches above ground on the exterior of a home?

I'm just assuming EMT is acceptable for this outdoor use. I actually had a 3rd electrician out but he proposed using an existing 20-amp line in the basement ceiling, somehow fishing or going through 20ft of floor joists to the outside wall, penetrating and running IMC on the exterior straight up to the bathroom and penetrating back in. His quote was about 250% more expensive than the others...

Thanks so much everyone for any answers.
 
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Old 08-28-15, 09:34 PM
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Welcome to the forums.

1) Are two THHN circuits allowed within the same 1/2" EMT conduit?
If the conduit is outside then it needs to be THWN. Two circuits can be run in one conduit

2) Are two Romex circiuts allowed within the same 1/2" EMT conduit?
Romex is not used in conduit

4) Can an EMT conduit not be run a few inches above ground on the exterior of a home?
If it's attached to the bottom of the house I don't see an issue. It will rust eventually. Compression fittings are required for EMT connections outside.

Run the circuits as 20A lines.
 
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Old 08-28-15, 10:20 PM
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Thank you.

Would Aluminum EMT be preferable then? I was thinking galvanized EMT would be stronger if strength is ever an issue, but was also not offered any other option.

It's interesting the one electrician said we'd have to switch to Romex for 2 circuits when that's not even allowed in conduit. The other's quote actually has THHN spelled out on it, which we discussed, and neither mentioned THWN.

Is there an even better conduit option for a visibly prominent location on the back of our home? I know there's PVC but thought it would be less attractive, so when EMT was suggested I didn't ask. Whatever we get it will shortly thereafter be painted by house painters.
 
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Old 08-28-15, 10:40 PM
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IMC.... aluminum conduit .... is larger in diameter.
The IMC is like threaded pipe so it is stronger but costlier to purchase and install.

PVC is tough to keep straight and true. EMT is probably your best choice.

THHN is high heat wire. THWN is water resistant...... although now most wire is rated THHN/THWN.

National Electrical Code® (NEC®) 2005 Article 358, EMT can be installed indoors or outdoors, in dry or wet locations, exposed or concealed, in all kinds of atmospheric conditions, and in
hazardous locations, when in accordance with the NEC® and providing it will not be subject to severe physical damage during and after installation and is properly protected against corrosion.
 
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Old 08-29-15, 05:49 AM
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EMT can rust outside, but depending on your installation, it can take 20 years or more. I have seen many older EMT pipes on rooftops and are not rusted. Steel EMT would be my first choice, PVC #2.

1) Are two THHN circuits allowed within the same 1/2" EMT conduit?
You can run a total of about 6 - 20 amp circuits is a 1/2" conduit. Not an issue.

2) Are two Romex circiuts allowed within the same 1/2" EMT conduit?
I will have to disagree with PJ on this. Yes, Romex is allowed in conduit, BUT if it is outdoor it needs to be UF. Yes, two circuits are allowed, BUT only if the pipe is sized for the two cables. 1/2" is likely not big enough for 2 - 12/2 UF cables. I think what PJ was saying is that it is not a good option to run two UF cables in a 1/2" conduit, and I would be a little leery of an electrician that would suggest that. Running THWN in conduit is much easier.
 
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Old 08-29-15, 11:03 AM
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Thanks for the clarification Scott. I left a word out........
Romex is not used outdoors in conduit
 
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Old 08-29-15, 04:36 PM
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This has been so helpful. Thanks again.

If I choose the run that involves 50ft through the unfinished (and inaccessible except for a ceiling panel with no permanent stairs or ladder) attic space would it be common or acceptable to change wire types where the outdoor conduit enters the attic? e.g. THWN-in-conduit to NM-in-attic and wall?
Or would the same continuous wires/cable be used for the full run?

I ask because I'm considering laying the cable/wire through the attic myself and letting the electrician do the exterior work. He didn't take a look at the attic but said it would be very difficult, though I'm not at all sure why. It may just be his age/size, but otherwise I trust him more and would prefer to hire him.
Would a bundle of THWN wires be run across ceiling joists/trusses in an attic space? How would it be bundled together? There's a ton of NM wire already just laying across the joists everywhere, probably mostly powering ceiling cans, but I'd have to take a 2nd look.

I am confused about the romex in conduit, and guess I'm leery now about the electrician who suggested it. I recall reading something about "protected" cables not being restricted to the % fill rule, if the conduit is just for protection, but also that there may have been a maximum 4' length allowed? (I read this last night on a website but don't remember where since I didn't think it applied to me yet). Maybe that's meant more for a UF option?
 
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Old 08-29-15, 05:01 PM
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I ask because I'm considering laying the cable/wire through the attic
You can use cable which is easiest but if you use wire it will need to be in conduit.
Would a bundle of THWN wires be run across ceiling joists/trusses in an attic space? How would it be bundled together?
To repeat, must be in conduit so cable would be easier. You can use a junction box to transition to THWN where it leaves the house and enters the conduit.
I recall reading something about "protected" cables not being restricted to the % fill rule,
That refers only to short lengths used as sleeves not continuous runs of conduit.
 
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Old 08-29-15, 06:35 PM
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As mentioned, individual wires like THWN are required to be in conduit. Converting the wiring method in the attic to NM-b cable makes sense as it would be easier to route the cables where they need to go. There would be a junction box up there, not a big deal as the attic is accessible. (Just not readily accessible)

Just wondering, how old is your house? Is the main plumbing stack accessible in the basement? Where is your main panel? I have fished many of home runs along side the main plumbing stack using jack chain. Best one is from the attic to the basement through two floors in between.
 
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Old 08-29-15, 06:46 PM
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Cables can be sleeved in conduit if the sizing rules are followed. The NEC does not specify a length limit. Sizing is based on the largest diameter of a cable.
 
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Old 08-31-15, 10:43 PM
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Thanks everyone.

Our home was built in 1991. The main plumbing stack is in fact accessible, but I will need to head back up into the attic tomorrow to see what I'm looking at in terms of fishing wire alongside it. I assume NM-B would be fine for this as well.
It wouldn't be the shortest route, that's for sure. Our panel is on the rear exterior, near the western side of our home outside the walkout basement. The tub is also on the rear, on the 2nd story far east corner. The main plumbing stack is right next to an interior corner on the front of our home, roughly in the middle. If it can be fished alongside the stack, I'll still have to figure out how to get a line from the panel on on the rear exterior though the finished rear half of the basement to where the storage area is in the front half with the main stack.

Looks like I've got some thinking to do.
 
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Old 09-02-15, 10:53 AM
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Well...
Although the main stack is accessible in the basement, it takes an angle somewhere to vent to the back portion of the roof, even thought it starts near the front wall of our home in the basement. I can see where it likely does this, as there's a large void in the wall next to our spiral-shaped staircase. Fishing wire through that doesn't seem possible though.

Next option. How close to a gas fireplace vent can a wire be run? This sounds like a bad idea, given, but there is a 4'-5' wide by 2' deep opening all the way down with only an 8" vent in the center. It would be relatively easy to send a wire down the outer edge, and it would exit just around the corner from the main panel (the bottom of the chimney/fireplace) creates an overhang above the sloped ground on the side of our home). Securing the wire would be the problem, depending what's required and if there are any tricks. I'd never do this if it were dangerous, but on the off chance it'd be ok somehow I have to ask.


Thanks.
 
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Old 09-02-15, 12:45 PM
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Do you know what rating class the chimney stack is? Is it single wall, double wall vent pipe? Wood framed or masonry?
 
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Old 09-02-15, 04:45 PM
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Although the main stack is accessible in the basement, it takes an angle somewhere to vent to the back portion of the roof
It likely does this in the attic.
 
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Old 09-02-15, 05:55 PM
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Cables that are fished are not required to be secured like in exposed work.
 
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Old 09-03-15, 01:27 PM
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Well I spent a ton of time yesterday hanging out in my attic...

I do not know the class rating of the chimney chase. It is wood framed, though, and someone cut a hole in the attic wall (sheathing) just large enough for someone my size to squeeze through and go inside the chimney area. There is even plywood "floor" that comes within a couple inches of the vent, where it meets the vent flashing or flange. There's also a 10" hole cut through the plywood "floor" at the attic level next to the vent, through which I can see 9ft down to what I presume is the firestop. 9ft below that would be the floor of the main level. To be clear, this room has an 18ft ceiling.

I'd love to pull up the 2ft piece of siding at the firestop level, pull aside the sheathing and bore through the 2x4 frame to run the cable all the way down through the bottom of the chimney (patching with fire rated caulk?). Then it would just be a 10ft run of conduit around the corner to the panel, instead of the 70ft run along the outside.

Question 1:
Does the junction box where interior NM-B will be spliced to THWN have to be interior to the wall, or can it be mounted on the exterior (underneath the chimney protrusion in this case).

Question 2:
I thought a google search would answer this seemingly simply question but nothing comes up. What is the best (most attractive) way to run 1/2" EMT conduit horizontally across a 5" rain gutter running down the corner of our home? Just bend around it? A few elbows? Go behind it somehow? What is normallly done in this situation?

Thanks all.
 

Last edited by joeyjoey; 09-03-15 at 01:44 PM.
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Old 09-04-15, 10:02 AM
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New questions to add:

3) Does any penetration (drilled hole) through a top plate require firestop foam or something similar? I don't see this around any of the other penetrations from the attic into the 2nd story walls in our 1991-built home, but was looking at the international residential code and now I'm confused.

4) Would the same suffice if we penetrate one of the outer 2x4 frame members in the chimney frame at the firestop level? Again, it's a gas fireplace. The interior of the chimney is wood frame and plywood and thermo-ply sheathing like on the rest of our home. No insulation except some kind of chunk of foam laid down on top of what I assume may be a firestop 9ft above the main floor.

5) Maybe this isn't not worth asking, but as mentioned before the chimney creates an overhang on the exterior of the home, so essentially you can walk under it. I assume it would be ok to mount an LB with 1/2" nipple to the underside, coming out the bottom? I'm not too worried about wires in this space since it is where the wires to power the fireplace blower, etc. already are anyway.
 
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Old 09-04-15, 11:28 AM
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Yes, any penetration between floors or any other rated firewall requires firestop caulk or foam. This was not the case in 1991. From a fire safety and energy conservation point of view, you might as well caulk up the existing ones if you see them as you crawl by in the attic.

With a gas fireplace, it's probably a class B chimney with double wall pipe, but you should try to verify this before adding wiring to the chimney chase. The gas fireplace should indicate its vent type somewhere on the labelling. Penetrations through this space should be caulked up and the chimney pipe should enter through plates or gromits. If it is B chimney, you can run wiring inside the framing.

There's no problem running the wiring under the chimney bump out.
 
 

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