10 Gauge wire with 30amp circuit and Baseboard Heat?
 

An older addition has 2 baseboard heaters wired to 1 thermostat, and I need to extend the wire to move the thermostat to a new location.

The baseboard heaters are probably about 10+ feet long each. Unsure their wattage.

From what I can see on the current wiring, it looks like 10 gauge, it says 10TW 600V on it.I wanted to confirm that I should use 10 gauge wire since I wasn't fully sure if 10TW was 10 gauge, or even thicker (8 or 6).

In the panel this is wired up to a 2 space, 30 amp breaker with a common trip, like this one:http://electrical.hardwarestore.com/...er-605041.aspx

Should I use 10 gauge wire?

10 TW is 10 guage wire. It precedes the current THHN or THWN wire. It was common 20-30 years ago and was replaced by the current wire designations. You will notice that the insulation is considerably thicker and less "slick". THHN is much easier to pull through conduit, and the newer wire is designated for wet locations (THWN). 10 guage wire is what you should use.

Thanks, I was hoping to hear that. You are right this wire looks so darn thick but I was suspecting 10 gauge with an old school coat.

Is 10 Gauge NM-B acceptable?

Sounds like i'll be off to the store to buy 10 gauge wire tomorrow.

Can anyone confirm if NM-B is ok in this scenario? Or must I use THHN? This is an inside application.

10 NM-B will be fine too.