Heating Load Conductor Sizing


  #1  
Old 05-12-15, 02:40 PM
T
Member
Thread Starter
Join Date: Oct 2002
Location: MINNESOTA
Posts: 161
Received 0 Votes on 0 Posts
Heating Load Conductor Sizing

Hello,

I have two heating loads within 40' of my 277/480 panelboard. One is 16.6a and the other is 23.5a. They can both be circuited to a 3-pole 480 volt circuit. They are continuous load.

I have sized the conductors by (16.6+23.5)*1.25 to get 50.1 or #6 AWG.

Is this correct? Do I need #6 throughout the circuit?

Tripper
 
  #2  
Old 05-12-15, 02:49 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 62,167
Received 1,525 Votes on 1,408 Posts
Will you be running an additional breaker, for protection, at each heating unit ?

You can't connect two units to a single breaker as the breaker size is too large to correctly protect each heater.
 

Last edited by PJmax; 05-12-15 at 04:02 PM.
  #3  
Old 05-12-15, 07:13 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,823
Received 111 Votes on 98 Posts
You need to refer to the manufacturer's instructions for maximum overcurrent protection for each heater.
 
  #4  
Old 05-16-15, 12:36 PM
Mr.Awesome's Avatar
Member
Join Date: Oct 2013
Location: Canada
Posts: 592
Received 0 Votes on 0 Posts
Ultimately, Joe is right.

Is this a commercial or residential (480V acreage shop?) setting though?
CEC states you can put multiple heaters on a circuit so long as they do not exceed 60A commercially (unless the loads are balanced, then you may exceed in a 3 phase system) and 30A in a residential setting. Maybe the NEC has the opposite opinion on this subject but I can't see it being much different.
CEC has crazy sizing rules for heating circuits so someone versed in the NEC should help you with that.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: