THHN vs Romex - Price the only consideration?

[Spudland_Dave]

So still thinkin about how I'm gonna go about wiring up my larger circuits... I've got 2 50A, 1- 40A Compressor and a couple of 30A "Utility" outlets for future machine tools....all 220v

Priced out 6-3 Romex at 2.00 a foot...Looking roughly at THHN Prices (Home Depot Online, local supply might be less), I could get 500' worth of THHN in the 4 colors for 1.41 a foot total... Add some 3/4" ENT Tubing (Smurf Tube) at .37 Cents a foot and the price gets closer but still less then the Romex.

Both Romex and THHN should get me my 50A rating (Still baffles me why its ok to use THHN #8 on 50A, but it is what it is)...

For you guys more experienced then myself...Go with THHN or the Romex? And Why?

 

[RABRods]

Now I am not electrician/expert...

I am using THHN/THWN for a few reason over the romex.

1: I plan to use surface mounted EMT so that I can reorganize if necessary and not have to plan and pay for enough circuits now and run all through wall before finishing dywall/insulation.

2: From the prices I have seen the costs comparing individual wires (supply house not Lowes) & EMT compared to Romex are similar, so the extra protection of wire in conduit compared to hiding in the wall where I may accidently damage years down the road is a bonus to me.

3: Using THHN/THWN in dry conditions you have higher allowable ampacity wire size due to the insulation temp rating. From my understanding, the 75 C column for terminations if your device termination is 75 of course & 90 C column for conduit fill derating.

I hope I didnt confuse any further.

-Billy

 

[matt151617]

It's not the price of the conduit that will get you, it's the elbows, connections, bender, etc. I have a feeling it will either be the same price or a little more expensive to run the EMT/THHN. The only nice part with conduit is it's easy to upgrade or pull a new line. Not quite so easy with Romex and much worse if you close the Romex inside a wall.

 

[Steevo]

Romex is faster and a lot less work to run when the wall studs are open and ready.

Surface mount EMT and THHN are easier for retrofit or changes later.

The cost is too close to be a point of consideration.

 

[BigGMC]

It's not the price of the conduit that will get you, it's the elbows, connections, bender, etc. I have a feeling it will either be the same price or a little more expensive to run the EMT/THHN. The only nice part with conduit is it's easy to upgrade or pull a new line. Not quite so easy with Romex and much worse if you close the Romex inside a wall.

But the OP is thinking of using ENT the blue convoluted plastic tubing.

Spud-
I personally dont like the stuff but that's just IMO. Once stuffed full of heavy copper, that smurf tube is going to want to sag all over the place. Assuming you plan on surface mounting it, it's gonna look like ****. The stuff also offers minimal protection against pinching/abrasion and nearly no protection against heat (think near welding table - grinding sparks, weld splater).

 

[40cpe]

What about running multiple hot legs along with a neutral and a ground in pvc conduit? Is this kosher to be more cost effective by eliminating duplicate neutrals and grounds as you would when running multiple circuits of Romex along the same route? Both legs of the 240V would be run to reduce the neutral load.

 

[Aceman]

Run Romex.

 

[theoldwizard1]

My buddy went all the way with EMT in his workshop/barn. He didn't want the horses nibbling on Romex !

 

[Spudland_Dave]

But the OP is thinking of using ENT the blue convoluted plastic tubing.

Spud-
I personally dont like the stuff but that's just IMO. Once stuffed full of heavy copper, that smurf tube is going to want to sag all over the place. Assuming you plan on surface mounting it, it's gonna look like ****. The stuff also offers minimal protection against pinching/abrasion and nearly no protection against heat (think near welding table - grinding sparks, weld splater).

I could use EMT if I wanted...But I was viewing Smurf Tube as a "DIY" Romex for lack of better terms...buy the conduit now, run my boxes and conduit...finish insulating the building then hang my sheetrock, and then when I get time, pull the wire thru for whatever I need. So for all intents & purposes, the conduit would be run IN the wall and above the trusses just as I would romex...if I could see it, you bet your rear end, I'd be using EMT.

Was just thinking, I could save 70 bucks if I went with a 10ga Ground..

All my plans got screwed to hell when I scored a lift of 1/2" x 54" x 12' Sheetrock for 3.00 a sheet...that was after getting 1800 sq/ft of insulation for a price I couldnt refuse....now I'm tripping over myself in the garage, lost the truck bay, and am being rushed to hang it all...my original plan all along was to get the building up, wire things up slowly, and when done electrical do the insulation & sheetrock...My FIL is probably gonna come down at Christmas for a week while I'm on vacation as well to help out. Even last night I started wiring up some of the circuits to Accessible J-Boxes which I'll wire up when I have more time....At least if I could get a length of conduit up the wall from my major boxes and into the attic space, I can splice/join the conduit and run wires home run when I get a chance.....Mind you, this is only for the major circuits...things like Welder, Plasma, Compressor, etc... normal 20A outlets I'm just banging in every 5'...Romex all the way for that. 2.00/ft for 6-3 is too expensive to bang outlets in just in case...

 

[ishiboo]

Can also run romex in ENT

 

[Midnight_America]

What does your local code specify? Regarding interior wiring, Romex is against code where I live. Everything here must be inside EMT, and Romex can't be used inside that EMT. Sometimes some non-metallic is allowed, depending on what has been previously discu$$ed with the inspector. Greetings from Illinois.

 

[ishiboo]

What does your local code specify? Regarding interior wiring, Romex is against code where I live. Everything here must be inside EMT, and Romex can't be used inside that EMT. Sometimes some non-metallic is allowed, depending on what has been previously discu$$ed with the inspector. Greetings from Illinois.

That's pretty much an Illinois only thing. The rest of the US has majorly adopted NM like 40 years ago.

 

[BFBOB]

Well, some places they're a bit paranoid about fire. Remember the Great Chicago Fire?

Oh, wait... that was kerosene.

never mind

 

[Norcal]

What does your local code specify? Regarding interior wiring, Romex is against code where I live. Everything here must be inside EMT, and Romex can't be used inside that EMT. Sometimes some non-metallic is allowed, depending on what has been previously discu$$ed with the inspector. Greetings from Illinois.

That is only where union featherbedding rules do not allow NM cable.

 

[Spudland_Dave]

What does your local code specify?

Absouletly nothing at all...if I wanted to run Porcelain knobs and bare copper wire in the trusses like they did in 1925, I would just need to locate a source for the Knobs..Heck maybe I could upgrade and get some plastic knobs? then I could post on whether I should use Soild or Stranded bare wire on my attic knobs. Wonder what the guys down at the electric supply would say if I walked in looking for that stuff...

All that being said, I do try to meet & exceed portions of the code that actually make sense and have reasoning behind it. Not just "Because its what NEC says"

 

[Midnight_America]

Well, some places they're a bit paranoid about fire. Remember the Great Chicago Fire?

Oh, wait... that was kerosene.

never mind

BFBOB: Has nothing to do with fire, it stems from issues/demands concerning the Chicago Unions. I remember in the 1970's that Chicago was the only city in the country that IBM shipped equipment to that had a requirement that the electrical cord on said equipment couldn't be longer than six feet. Shorter cords = more receptacles = well, you get the picture.

 

[BFBOB]

BFBOB: Has nothing to do with fire, it stems from issues/demands concerning the Chicago Unions. I remember in the 1970's that Chicago was the only city in the country that IBM shipped equipment to that had a requirement that the electrical cord on said equipment couldn't be longer than six feet. Shorter cords = more receptacles = well, you get the picture.

Thanks for bursting another of my bubbles. Here I thought it was over safety concerns. Overblown safety concerns, but safety concerns nonetheless.

 

[wyliesdiesels]

What about running multiple hot legs along with a neutral and a ground in pvc conduit? Is this kosher to be more cost effective by eliminating duplicate neutrals and grounds as you would when running multiple circuits of Romex along the same route? Both legs of the 240V would be run to reduce the neutral load.

The thing is, the circuits he is talking about don't need a neutral(240v devices) so this is inconsequential. Yes, he could use a shared egc, but that will only save him in the home run conduit and then he would have to splice the ground to each outlet. Will only save him 3 or 4 egc wires.

 

[Spudland_Dave]

The thing is, the circuits he is talking about don't need a neutral(240v devices) so this is inconsequential. Yes, he could use a shared egc, but that will only save him in the home run conduit and then he would have to splice the ground to each outlet. Will only save him 3 or 4 egc wires.

Well thats partially true....instead of NEMA 6-50R's, I've gone with 14-50R's in my existing garage, and already have one wired up as such...so yes, I would need the 4 conductors on a couple of them. When I posted the daisy chaining post, what I really had in mind is wiring a 14-50R next to a 6-50R (seperate boxes, I'd put one on each side of a stud type thing)

TECHNICALLY I have rarely used the Neutral in my attached garage 50A outlet...but I have used it a few times.

 

[ralf-who]

I live in Cook county and, yes, the rules regarding the use of wires in EMT or raceways is pretty strict. Some would say it is a consequence of undue influence from unions or an overstatement of safety.

I really didn't give it a lot of thought until my folks moved to Los Angeles and my mom asked me to put an outlet under the control of a wall switch. (wall switch was already there, controlling an overhead light).

"Sure", I said, "no big deal. I'll just draw a wire from the outlet to the switch".

Well, that job would've taken 10 minutes in Chicago. In LA, it meant breaking into the wall. Certainly more than a 10-minute job.

From a consumer standpoint, having everything "in-pipe" might be a construction hassle but if you ever need to change anything you'll be glad it's like that. Everything "in-pipe" means that every wall outlet, every overhead light, and every wall switch is connected to each other (although perhaps not directly) and changing stuff , short of installing a NEW outlet or switch or ceiling fan is a breeze. Just pull a few new wires.

The second bonus, one that is not immediately obvious is the animal-proofing that wiring-in-pipe provides. The first time a squirrel (may he rest in peace) gnawed thru my Mom's Romex in LA gave her immediate appreciation of that. And it was also not the last time.

And third, everything in-pipe means that there is a ground continuity that is not present (automatically) in Romex.

Yeah, piping a new house or garage is more expensive and time consuming but the first time you need to change something you'll appreciate it. Add to that the safety you get when you (don't) inadvertently ground-isolate an outlet.

 

[ralf-who]

EMT. Read my post.

 

[Spudland_Dave]

From a consumer standpoint, having everything "in-pipe" might be a construction hassle but if you ever need to change anything you'll be glad it's like that. Everything "in-pipe" means that every wall outlet, every overhead light, and every wall switch is connected to each other (although perhaps not directly) and changing stuff , short of installing a NEW outlet or switch or ceiling fan is a breeze. Just pull a few new wires........

Yeah, piping a new house or garage is more expensive and time consuming but the first time you need to change something you'll appreciate it. Add to that the safety you get when you (don't) inadvertently ground-isolate an outlet.

Been a while since I made my OP, but I can say you've got a valid point there and I agree. I'm finding myself pulling a whole lot more ENT then I thought I would, but its just as easy as running romex, allows for future changes and what I like is some circuits where I dont know what I want to do just yet (such as cieling fan...Light or no light) but I need to sheetrock, so I can put the box in...run the conduit up into the attic and then I'll extend it to wherever I need when I get a chance. Allowing me to proceed without worrying about the little details.

 

[rburke65]

Just put up a new shop and i did a combination of the romex and thhn. From my electrical panel, I first ran 4 runs of 3/4" PVC conduit under ground ( before I poured the concrete floor) to the four corners of the shop.....32'x56. I pulled 4 110 volts circuits to each area, into a 4 11/16" box. Then took a 12-3 Romex to the left and another to the right, running 2 circuits each way. This just saved me running and stapling romex up high in the trusses with my 13' ceilings, and I thought it would be quicker and possibly cheaper. Good luck.