Wiring for my 4800 W heater

Reply

  #1  
Old 12-22-15, 11:19 AM
Member
Thread Starter
Join Date: Jun 2013
Posts: 28
Wiring for my 4800 W heater

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/i...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
 
Sponsored Links
  #2  
Old 12-22-15, 11:38 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,052
Are you in Canada? In Canada they sell Red Romex, red, black, bare, for 240v. If in the US that isn't available. You use regular 2-conductor + ground NM-b (xx-2) and remark the white another color such as red or black.

A heater is a continuous load so the breaker must be 120% of the full load. A 25 amp breaker would be okay by code but the 30 amp breaker would be the usual. Cable must match or exceed the ampacity of the breaker so you need #10 even if you figure it at the lower 25 amps.
 
  #3  
Old 12-22-15, 11:44 AM
Member
Thread Starter
Join Date: Jun 2013
Posts: 28
hi Ray.

yes, in Canada

so, 10/2 is what I would require. using the ground for the third terminal on the plug?

and that ground should first be screwed to the box then run to the plug correct? that's how I would do a regular plug, I presume this to be no different?

thanks
 
  #4  
Old 12-22-15, 12:00 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,385
so, 10/2 is what I would require. using the ground for the third terminal on the plug?

and that ground should first be screwed to the box then run to the plug correct? that's how I would do a regular plug, I presume this to be no different?
No, use the ground for the third wire on the receptacle, not plug. A plug is a male cord cap with blades.
 
  #5  
Old 12-22-15, 12:01 PM
Member
Thread Starter
Join Date: Jun 2013
Posts: 28
hehe... yes, I often make that mistake... when I spoke of the plug I meant the receptacle

thanks
 
  #6  
Old 12-22-15, 12:13 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,052
And not really the "third terminal", the ground terminal (green screw).
 
  #7  
Old 12-22-15, 03:40 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
A heater is a continuous load so the breaker must be 120% of the full load.
Slight correction, Ray, at least in the US, a heater circuit must be 125% of the load. Still would be a 25 or 30 ampere circuit breaker in this example as well as #10 wiring.
 
  #8  
Old 12-22-15, 09:26 PM
Member
Join Date: Mar 2010
Location: USA
Posts: 3,097
deleted ...........................
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes