Hi again guys! I'm running about 8 feet of metal EMT conduit from a baseboard heater, into a junction box in the joist cavities of my basement (ceiling, or first floor joist cavity). The baseboard is 2000 watt, 240 volt, and my code here stipulates that 14/2 will suffice with 15 amp breaker. I'm going to run 12/2 and a 20 amp breaker for safety sake.

My questions are this, can you take the sleeve off the Romex 12/2 to run in the conduit, or do I have to get separate wires from the store? And, do I need to run a ground? If I do have to run a ground, does it have to be sleeved green , or can it be the bare wire from the Romex? I figure I can take the sleeve off the romex, and if I do have to run a sleeved green ground, I can just pick that wire up from the store. Anyway, thanks again for all your help!

You can run the #12, but use a 15A breaker. The fuse is more closely sized to the load.

You can run romex in conduit, but it's generally not recommended. The only thing to worry about is fill.
Use what's called pull boxes or LB's at the ends and a Romex connector for a strain relief.

If you want to use wires, you can use THHN bulding wire. The wires don't necessarily have to be the right colors. The ends can be taped the correct colors.

You can pass/sleeve the Romex into the EMT with or without stripping the outer sheathing.

It will be easier to strip it.

You need to use a cable to EMT coupling, see photo.

DO NOT just shove the cable into the EMT with some sort of connector as I shown.

My plan was to run #12 with a 20 amp breaker because my code says that I can have up to 3840 watts with this, and I may want to run another heater somewhere else in the basement. But I'm open to suggestions.

The picture I've attached is the cable connector that I use to connect romex to junction boxes and whatnot. How would I use TK's clamp with this system? To me, that means I'd come out of the heater using the clamp I've pictured (side puch out on the heater) and then right away into TK's clamp and into the conduit? At the heater, since this is on the surface of the wall, seems to be a bit odd? Maybe I'm missing something?

#12 yep. 240 * 20A * 0.8 (derateig factor)

This is the usual Romex connector we normally talk about: Amazon.com: Romex® Connector - 1/2 in.: Home Improvement

No, we both misunderstood. I believ we were thinging of a short length of conduit to say pass through say basement to attic. The other ends would be Romex without any conduit.

Look at these fittings: Conduit Fittings - Wholesale Electrical Supply Company

Particularly the Emt Set Screw Die Cast Connect fittings.

If your going conduit all the way then use building wire. THHN.

Yes, sorry for not giving enough info. It's a finished basement room, but ripping into the wall and running new wire isn't really practical in this instance. The heater is only about 12 inches from the corner of the wall. So I was going to have conduit run from it to the corner, use a 90 degree and run up the wall in the corner with conduit into the joist cavity into a junction box. From there I will run regular romex to the panel.

The EMT set screw die cast connectors are exactly what I was planning on using. But how would I use TK's clamp to clamp the romex, or can it run freely in the conduit, since its clamped to both the heater and the junction box?

Otherwise, you recommend using THHN rather than taking the sheathing off the romex? And if that's the case, do I run a ground, or is the conduit the ground?

Your missing it again. TK's solution allows you to use a piece of conduit with romex and NO junction box.

Example: You would need protection when crossing a stair.

Remember that junction boxes cannot be covered. You don't even need to splice.

You have the right idea. You have 12" to go with no splices, so remove the sheathing.

How dis 8 feet become 12"? That's what had me confused.

Alternatively, you could dispense with the junction box in the basement joist and just bring a properly secured piece of conduit down and use one of tk's connectors. It provides the strain relief for the Romex.

I'd envision the clamp holding the conduit as being the ones that attach firmly to the EMT and connect via a piece of allthread to a flange. A couple of nuts prevent the system from rotating. The standoff height depends on the length of the allthread.

Oh, I see. Using TK's clamp without a junction box. That makes total sense, and I should have thought of that.

Yes overall, its maybe 8 or 9 feet of total run. 1 foot along the baseboard and then maybe 7 or so feet up into the joists. Conduit straight from the punch out on the side of the heater all the way to the joists. Perfect, thanks guys again for all your insight!