Do I have large enough service to sub panel?

Reply

  #1  
Old 09-26-16, 07:55 PM
L
Member
Thread Starter
Join Date: Sep 2011
Location: Canada
Posts: 28
Received 0 Votes on 0 Posts
Do I have large enough service to sub panel?

I have a 3x10 cable running from house service panel to sub panel in pumphouse. Cable is fed off a fuse panel currently with 2x20A fuses, but could be upsized to 2x30.

Sub Panel has two 20A 120V breakers each feeding 15A gfci duplex outlet through 12ga wiring. Pump on one draws 9A max and space heater&controls on other 5A.

Sub panel also has one 15A 2 pole 240V breaker feeding a line heater that runs inside water intake out into lake. This has no gfci, but may, it seems, be required under Ontario (Canada)Electrical code.

There may be other options, but to get gfci with high mA setting (they are set at 10-30mA) I may have to install a new type 120V line heater. These are available with gfci built in. Draw would be 7A max.

120V load would now be 9+5+7 = 21A. Given maximum available service of 30A, could I do this with two existing 20A circuits or add a third 120V dedicated breaker for line heater?
 

Last edited by lakeresident; 09-26-16 at 08:51 PM.
  #2  
Old 09-26-16, 08:01 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,854
Received 1,336 Votes on 1,234 Posts
Since you have a 240v service out to the pumphouse...... try and balance your loads on the two legs.

Put 7A+5A=12A on one leg.
Put 9A on the second leg.
 
  #3  
Old 09-26-16, 08:50 PM
L
Member
Thread Starter
Join Date: Sep 2011
Location: Canada
Posts: 28
Received 0 Votes on 0 Posts
OK, THanks.

So I can use actual loads rather than max potential loads on the two legs?

Isn't 12A on one leg almost max for 15A duplex? Wiring/breaker are good for 20A, so would I change receptacles to 20A. Then I have potential of 2x20A or 40A on 30A supply? That is what was concerning me. But I suppose everything is still protected.
 
  #4  
Old 09-26-16, 09:03 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,854
Received 1,336 Votes on 1,234 Posts
You need at least two 15A receptacles on a 20A circuit and with a duplex receptacle you are good.
You could certainly install a 20A receptacle but it's not required.
 
  #5  
Old 09-26-16, 09:53 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,583
Received 13 Votes on 11 Posts
You could certainly install a 20A receptacle but it's not required.
Pete, he's in Canada. It has been posted here before CEC requires 20 amp receptacles on 20 amp circuits.

CEC: Rule 14-600 - Protection of Receptacles
Receptacles shall not be connected to a branch circuit having overcurrent protection rated or set at more than the ampere rating of the receptacle except as permitted by other Sections of this Code.

Not sure about the exceptions.
 
  #6  
Old 09-27-16, 12:12 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,854
Received 1,336 Votes on 1,234 Posts
Ahhhhhh...... yes. Canada.
 
  #7  
Old 09-27-16, 05:32 PM
L
Member
Thread Starter
Join Date: Sep 2011
Location: Canada
Posts: 28
Received 0 Votes on 0 Posts
Yes, canada :)

I now believe that is correct - I should install 20A T-slot duplex receptacles on each 20A circuit.

This brings me back to my question. Can I have two 20A circuits fed off a 3x10 30A max feed from main panel?

Or would I have to change the sub panel breakers to 2x15A?
 
  #8  
Old 09-27-16, 06:36 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,583
Received 13 Votes on 11 Posts
Actual load not size of the the breaker is what counts. So long as actual load does not exceed supplying breaker in the main you are okay.
 
  #9  
Old 09-27-16, 06:57 PM
L
Member
Thread Starter
Join Date: Sep 2011
Location: Canada
Posts: 28
Received 0 Votes on 0 Posts
Thanks Ray - Just checking! So just don't exceed the main panel protection. 20/25or30A fuses in this case depending on max load we can foresee.
 
  #10  
Old 09-27-16, 09:50 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,583
Received 13 Votes on 11 Posts
Yes. .
 
 

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