Details for wiring eletric heater

[Tomlaq]

Plan on installing a 7500 watt, ceiling hung unit heater.
I have the wire and breaker size req'ts. 2W 8ga with gnd and 40 Amp double pole breaker.
Trying to finalized a couple of details to make sure I'm not violating any NEC req'ts.
Wiring will be concealed in wall and run a few feet in finished ceiling.
It is my understanding that the exposed wiring must be within a conduit. Either metal or plastic.
I've seen examples showing the use of a junction box and transition to a flexible conduit a few feet to the unit.

My questions are:

Is a junction box mandatory? (Total horizontal distance from main panel will only be a few feet.)

Could I run the wire right through the box without splicing?

Ideally, I would like to just come out of the ceiling with a flexible conduit and connect it to the heater if a junction box was not mandatory.

 

[sberry]

Might not even need conduit, the main reason to pipe it is to protect the wire. If its up out of the way then run it to it. Less splicing the better.

 

[Tomlaq]

That sounds like a good common sense approach. I was just a bit concern about code requirements, just in case.

 

[wyliesdiesels]

The requirement to put wire in conduit is dependent on 2 things- type of wire and if its subject to damage.

Individual conductors such as THWN are required to be in conduit no matter what.

NM, SE style, etc can be surface mounted as long as its not subject to damage.

So what type of wire are you using?

 

[Tomlaq]

I got Romex® SIMpull® 8/2 NM-B with AWG 10 ground Wire. This is stranded wire that I was able to buy by the foot at one of the Home Depot stores.

So a junction box is not a req't?

 

[matt_i]

I think I'd forgo the junction box in the ceiling (could use a 4" cover plate from a square box to begin the flex conduit run). But, you'd want to buy a big-enough staple to put some strain relief on the NM, in the attic, close to where it penetrates the drywall.

I would shop carefully on the flex conduit. As usual you want some extra room in there to avoid getting the wire stuck. I am not sure if HD sells flex conduit "by the foot" above 3/4" dia...I ordered some 1-1/4" flex "by the foot" thru McMaster carr plus fittings for hardwiring a welder with #2 awg. There are probably many other sources, this is just one.

 

[Tomlaq]

Great idea on the "4" cover plate from a square box to begin the flex conduit run)" You read my mind on what top do with that penetration. Actually I could attach a box from within the attic to the sside of a joist. That would make it pretty secure.

Not sure what "big-enough staple" means. The rest I believe I get.

HD does have some short pieces of flex PVC with fittings on the ends, I believe. And I think they are about 3/4".

 

[sberry]

If I was going to put flex might skip the box and shove it thru the ceiling. But if i could make it legal with simply running the cable to it why fugg with more pieces you dont need. Simple is good. When I started wiring I thought I had to use every fitting they ever invented, today I am a lot simpler. It should look decent and if it's not noticeable then why complicate it.

 

[Tomlaq]

If I was going to put flex might skip the box and shove it thru the ceiling. But if i could make it legal with simply running the cable to it why fugg with more pieces you dont need. Simple is good. When I started wiring I thought I had to use every fitting they ever invented, today I am a lot simpler. It should look decent and if it's not noticeable then why complicate it.

I totally agree. It was the legal parts I wasn't sure about.
If my local inspector ever happens to see the short run of exposed cable across the ceiling, I can just tell him @sberry told me.

 

[Tomlaq]

Thanks everyone for all your help.
Great Forum!

 

[sberry]

I am sure it will be low on his list. They see some ****.