I have installed 9 "QuiteWarm Radiant Heat Film for under subfloor" to heat the floor above a crawl space off the the basement. The crawl space has a concrete slab and is tempered. This subfloor system is a 120v. system, with a total load of 900 watts, 7.5 amps for the 9 panels. Each radiant heat film panel comes with a separate black and white 12 ga. wire. The instructions say to run all the wires (black and white)to a junction box, wire them in parallel and run a 12/2 Romex to the Thermostat. The Thermostat gets power from a separate 15 amp breaker circuit. The thermostat has a built in GFI. My question concerns the single 12 ga. wires from the film panels to the junction box. Can the single 12 gauge wires be run exposed in the crawl space(fastened per code along joist or 2×6) or do they need to be put in conduit or something else?.
Thanks
Wiring – Can 12/2 cable be exposed in a crawl space
wiring
Related Solutions
Not sure what model equipment you're using, but it seems like the new thermostat requires a neutral connection. If this is the case, you'll want to make the connections as follows:
At the Thermostat
- Connect the black wire to the
Bterminal in your diagram. - Connect the white wire to the
Nor neutral terminal. - Connect the red wire to the Heat (and Cool if that's how it was on the old thermostat) terminal(s).
At the Junction Box
- Connect the white wire from the cable going to the thermostat, together with the other white wires in the box.
You don't have to do anything to identify the conductors. However, you'll have to worry about box fill, as these conductors will have to be counted in the fill calculation.
National Electrical Code 2014
Chapter 3 Wiring Methods
Article 314 Outlet, Device, Pull, and Junction Boxes; Conduit Bodies; Fittings, and Handhole Enclosures
314.16 Number of Conductors in Outlet, Device, and Junction Boxes, and Conduit Bodies.
(B) Box Fill Calculations.
(1) Conductor Fill. Each conductor that originates outside the box and terminates or is spliced within the box shall be counted once, and each conductor that passes through the box without splice or termination shall be counted once. Each loop or coil of unbroken conductor not less than twice the minimum length required for free conductors in 300.14 shall be counted twice. The conductor fill shall be calculated using Table 314.16(B). A conductor, no part of which leaves the box, shall not be counted.
Related Topic
- Wiring – share “C” wire on two thermostats
- Electrical – Fastening THHN cable in junction box
- Wiring – How to wire a switch between two 24V heating only thermostats to switch between thermostats
- Electrical – AFCI trips when adjacent breaker is switched on
- Wiring – Replacing old Electric Radiator Thermostat (220v) with a 4-wire Honeywell CT410B (Non-Programable)
- Wiring a Double Pole Thermostat to Replace a Single Pole 240 Thermostat
Best Answer
Yes a crawl space can have your 12/2 attached directly to the floor joists if going along the joist if going perpendicular a rat run is needed for smaller than 2 ea #6 or 3 ea #8 wires see exhibit 334.1 in the code , nmb in this location has been code for decades. Rat run or 1/2” plywood minimum. Note bored holes need no protection.