220 Volt Wiring size?

helpless handyman · 08-18-2008, 09:03 AM

I am in the stage of closing my walls in a basement renovation. I want to run some bx cable and leave it behind the wall for future use, if basement is not warm enough with the insulation. I need to know if 12/2 would do for a 25' run for a 220 volt circuit, or do I need 12/3, 12/4? I will not be doing the install, but rather have the wire inside the wall for future use. This will be for baseboard heater.

Thanks,

buletbob · 08-18-2008, 09:18 AM

I personally would run the 12/3 this way if the heat is not needed, you have the option at a later time to run two 15 or 20 Amp 110v circuits when needed. And you still have the option for the heat circuit if needed. GOOD LUCK BOB

rjniles · 08-18-2008, 09:23 AM

Quote:

Originally Posted by helpless handyman

I am in the stage of closing my walls in a basement renovation. I want to run some bx cable and leave it behind the wall for future use, if basement is not warm enough with the insulation. I need to know if 12/2 would do for a 25' run for a 220 volt circuit, or do I need 12/3, 12/4? I will not be doing the install, but rather have the wire inside the wall for future use. This will be for baseboard heater.

Thanks,

25 feet is not a problem. 2 wire cable is fine for base board electric units. 12-2 (20 amps)can supply up to a 4400 watt heater, if you plan on something bigger go with 10-2(30 amps). Run the cable from the cicuit breaker panel to the heater location. Also run a second cable of the same size (from the heater location) to the thermostat location (most baseboard electrics use line voltage thermostats). I would also run a low voltage thermostat wire (3 wire)to parallel that second wire just in case. Unless it is not allowed in your locality I would use NM (Romex) cable, it is cheaper and easier to handle.

helpless handyman · 08-18-2008, 09:25 AM

Thanks BuletBob

, sounds good!

helpless handyman · 08-18-2008, 09:28 AM

Thanks Rjniles

. Almost forgot that run to the thermostat!

Speedy Petey · 08-18-2008, 04:31 PM

Quote:

Originally Posted by rjniles

212-2 (20 amps)can supply up to a 4400 watt heater,

A 20A 240v circuit for electric heat can supply 3840 watts, NOT 4400 watts.

Electric heat shall be considered a continuous load; which is 80% of a circuit, or 125% of the load.

petey_c · 08-18-2008, 06:46 PM

hh, What rjniles and Speedy Peety are saying is good advice. Work backwards. Figure out how big of a heater you'll need, then run the correct size wire. You can also mount a thermostat directly on the heater (unit stat). I prefer a wall mounted t-stat.
I don't like to run a 3 wire for two separate circuits. There's always a possibility for too much current to try and get back to the panel on a small neutral. For arguement's sake, 13 amps on each of the "hots", that means 26 amps coming back to the panel on a single 14 ga. wire. Which is only rated for 15 amps. Most cases it would probably never happen, but you should always err on the side of safety. pete

chris75 · 08-18-2008, 06:53 PM

Quote:

Originally Posted by petey_c

.
I don't like to run a 3 wire for two separate circuits. There's always a possibility for too much current to try and get back to the panel on a small neutral. For arguement's sake, 13 amps on each of the "hots", that means 26 amps coming back to the panel on a single 14 ga. wire. Which is only rated for 15 amps. Most cases it would probably never happen, but you should always err on the side of safety. pete

What the heck are you talking about? If you had 13 amps on each leg, the neutral would read zero....

junkcollector · 08-18-2008, 07:17 PM

Probably a better argument for not using a multiwire circuit is the use of AFCIs.

Speedy Petey · 08-18-2008, 07:27 PM

Quote:

Originally Posted by petey_c

I don't like to run a 3 wire for two separate circuits. There's always a possibility for too much current to try and get back to the panel on a small neutral. For arguement's sake, 13 amps on each of the "hots", that means 26 amps coming back to the panel on a single 14 ga. wire. Which is only rated for 15 amps. Most cases it would probably never happen, but you should always err on the side of safety. pete

Wow!

Petey, please be careful giving advice such as this. You are 180 degrees off on this as Chris stated.

Be sure what you are saying is correct and code legal. This can be pretty important stuff here.

chris75 · 08-18-2008, 07:27 PM

Quote:

Originally Posted by junkcollector

Probably a better argument for not using a multiwire circuit is the use of AFCIs.

most electric baseboard heat is 240v anyhow....

junkcollector · 08-18-2008, 09:31 PM

Quote:

Originally Posted by chris75

most electric baseboard heat is 240v anyhow....

I know.

I was talking about:

Quote:

Originally Posted by buletbob

I personally would run the 12/3 this way if the heat is not needed, you have the option at a later time to run two 15 or 20 Amp 110v circuits when needed. And you still have the option for the heat circuit if needed.

Sorry I should have been more clear.

chris75 · 08-18-2008, 09:42 PM

Quote:

Originally Posted by junkcollector

I know.

I was talking about:

Sorry I should have been more clear.

Not your fault, I didn't see the part you highlighted.

theatretch85 · 08-19-2008, 01:25 AM

I guess petey_c has never heard of a Multi-Wire Branch Circuit before?

It would be a good idea that in the event you don't need the heat (since it seems you currently are not sure whether you will or not) preparing for it with a run of 12/3 or 10/3 now would not be a bad idea. Could give you those two dedicated circuits for a home theater or simply allow for a small plug-in heater for the really cold days.

You wouldn't need the neutral wire if you use it for baseboard heat, but its one wire that would be "extra" in the event you do actually put in the heaters (rather than wishing you had pulled it earlier).

helpless handyman · 08-19-2008, 09:53 AM

Thanks to all you guys for the quick reponse and the geat ideas. I had plenty of 12/2 left from the reno, so I decided to run two dedicated lines just in case. I know the 12/3 would have been good, but would have to go out and buy it. I used what I had. Thanks so much to all..