[Pabs]

Hi
I have a construction heater rated at 4800W. it will be installed on a 30 amp double pole breaker. I had this installed in my previous house. and over there, it seems it had been installed using 12/2 wire (red, black and ground).
it worked for years but now I doubting if it wasn't done wrong

from what I understand the 30 amp breaker can take up to 7200W (30* 240) so plenty of room for the heater
Now, if using 12/2 wire then that means it can't take more than 20amps correct? and given the same math that would give me exactly 4800W (20 *240)

they had the red and black on either side and the ground on the bottom screw of the plug. but looking online today I saw that they used a 10/3 and brought red and black to either side and the neutral to third screw (bottom) where I had the ground before. I presume the ground wire would just be screwed to the box in this scenario?

see image in link
http://www.do-it-yourself-help.com/images/30amp_receptacle.gif

I had ripped out the heater, plug and wires when I left as my ex didn't need or want it.
can it go back with 12/2 or is it necessary to upgrade to 10/3?
if I don't have to install 10/3 that would save me some money as I have the old wiring...

thanks

 

[Jump-start]

Is the heater 120/240 or straight 240? A none grounding NEMA 10-30 would not be complaint today.


10/3 if the heater is 120/240, 10-2 if straight 240, however 10/3 can also be used for straight 240 as long as you cap off the neutral.

 

[Pabs]

one of these
http://www.kent.ca/kbs/en/product.j...=jump&navId=2623&prdId=6846047&catalogId=2623

so, that would mean 10/2 and the ground would be used on third terminal correct? like it was before... only difference being the wire would be bigger

 

[Jump-start]

one of these
http://www.kent.ca/kbs/en/product.j...=jump&navId=2623&prdId=6846047&catalogId=2623

so, that would mean 10/2 and the ground would be used on third terminal correct? like it was before... only difference being the wire would be bigger

Yes, 10/2. If using a plug you will need a NEMA 6-30r as shown here on page 6 of the manual:

http://www.dimplex.com/cms/publications/Construction_Heater_DCH-EMC_-_7208970100r04_EN.pdf

 

[Bob Sanders]

Yes, 10/2. If using a plug you will need a NEMA 6-30r as shown here on page 6 of the manual:

Maybe in your neck of the woods you can take the plug off and hard wire it but here you can't. It is a "portable" heater and therefore illegal to remove the plug and permanently hard wire.

 

[Jump-start]

Maybe in your neck of the woods you can take the plug off and hard wire it but here you can't. It is a "portable" heater and therefore illegal to remove the plug and permanently hard wire.

Never said it was OK to cut the plug off, simply if the unit came with one a NEMA 6-30 would be used. It sounded like the OP was considering adapting the plug to a NEMA 10-30 receptacle which is a no-no.