wires in plastic conduit

[pudgybear]

my garage walls are drywall covered, so I am running plastic conduit from the power source to a switch mounted on the wall and then to a ceiling light, so what i understand is that you run single wires and NOT romex through plastic conduit, WHY? wouldn't it be cheaper to run ROMEX?

 

[Steevo]

It is a code and temperature rating thing.
Romex (NM) is meant to be exposed and THHN/THWN is meant to be enclosed.

 

[Highbeam]

No, you can run romex in conduit so long as it is not in a wet location. I've run plenty of romex in conduit and passed inspection. As you, I found it can be cheaper to buy romex than indidual THHN strands. However, romex is solid core so it will be harder to pull through bends.

 

[Spudland_Dave]

Perfectly fine to run Romex in conduit, its really more of a Conduit Fill/Capacity issue then a safety/code issue.

Long story short...if you just need to run a single wire, probably best/cheapest to run the romex in the conduit. If you need to get multiple wires into a box, because of the size calculation of Romex for conduit fill purposes, you might end up with a 1.5" Conduit in order to meet conduit fill/code specs. Where as if you used THHN, you could probably get it all into a single 1/2" conduit. (Yes, I'm exaggerating a bit for the purposes of explanation)

 

[Steevo]

Well damn! There I go learning something again.

 

[rlitman]

No, you can run romex in conduit so long as it is not in a wet location.

There is another catch that probably does not apply to a garage. Some Romex sizes have a down-sized ground wire, and that may not be acceptable for certain circuits (such as a jacuzzi).

 

[wyliesdiesels]

As HIGHBEAM has said, Romex can be run in conduit, in DRY LOCATIONS ONLY. Has nothing to do with heat, as steevo said. The main issue is conduit fill capacity and because of thickness, can be a pain in the **** to pull, especially if there is bends...

There is another catch that probably does not apply to a garage. Some Romex sizes have a down-sized ground wire, and that may not be acceptable for certain circuits (such as a jacuzzi).

Do u have a code cite?(hint: u wont find one) According to what?

EGCs/ground wires are sized based on breaker size. Reduced ground wires in NM-B wire is code approved. As an example, #8 Romex w/ #10 bare ground. #8 Romex has an ampacity of 40a and a #10 EGC is good upto 60a!

 

[Highbeam]

There is another catch that probably does not apply to a garage. Some Romex sizes have a down-sized ground wire, and that may not be acceptable for certain circuits (such as a jacuzzi).

I've never heard of such a thing. I've installed a couple of spas using 6/3 romex with smaller ground. I believe that the 6/3 uses a #10 ground.

 

[rlitman]

Pools and hot tubs among other things require a full sized and insulated ground. Romex and UF are not suitable.

Equipment grounding (bonding) conductors must be insulated for permanently installed pool, outdoor spa, and outdoor hot tub equipment [680.21(A)(1), 680.23(F)(2), and 680.25(B)].

 

[Highbeam]

Pools and hot tubs among other things require a full sized and insulated ground. Romex and UF are not suitable.

Equipment grounding (bonding) conductors must be insulated for permanently installed pool, outdoor spa, and outdoor hot tub equipment [680.21(A)(1), 680.23(F)(2), and 680.25(B)].

Interesting. The line you quote requires insulation on the ground. Maybe the insulated romex jacket counts? What about this full size thing?

 

[wyliesdiesels]

Pools and hot tubs among other things require a full sized and insulated ground. Romex and UF are not suitable.

Equipment grounding (bonding) conductors must be insulated for permanently installed pool, outdoor spa, and outdoor hot tub equipment [680.21(A)(1), 680.23(F)(2), and 680.25(B)].

I read those sections and I see NOTHING about an EGC required to be the same size as the ungrounded conductors(you didnt say that but I'm assuming thats what you meant):

• 
  *.21(A)(1) deals specifically with wiring to pool motors(not feeders)
  *.23(F)(2) deals with lumineers(again no mention of feeders)
  *.25(b) says the conductor shall be insulated and sized according to 250.122 which points to/ references T250.122, which is the table for sizing EGCs of which Romex with smaller than conductor size EGCS comply with!!

 

[brewchief]

IIRC there has been discussion on this before and I think it had to do with increasing the wire size to compensate for voltage drop and need to increase the ground proportionally.

 

[wyliesdiesels]

IIRC there has been discussion on this before and I think it had to do with increasing the wire size to compensate for voltage drop and need to increase the ground proportionally.

Yes, thats true but a different subject than what rlitman is saying- that EGCs are required to be the same size as the ungrounded conductors when feeding pools, spas, etc.