ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Any Woodworkers here?
by Bill Addiss - 05/10/21 11:26 PM
Do You Travel?
by Bill Addiss - 05/10/21 11:13 PM
Just be aware of this...
by gfretwell - 05/10/21 07:30 PM
Your favourite food?
by gfretwell - 05/10/21 06:13 PM
Lock-down Thread
by gfretwell - 05/10/21 06:12 PM
New in the Gallery:
2020 - 2021 Winter Project
Garden 2021
Who's Online Now
0 registered members (), 13 guests, and 12 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Subpanel Calculation #32851 01/04/04 05:56 PM
Joined: Jan 2004
Posts: 1
N
Nebraska Offline OP
Junior Member
I recently added a sub panel to my house It contains 3 15 amp breakers, 2 15 amp tandem breakers, 1 20 amp breaker and 1 2 pole 30 amp breaker for a water heater, all the 15's and the 20 are for general purpose receps. How do you calculate the size of breaker to put this sub panel on. Taking 80% of all the breakers added together just doesn't seem right, maybe it is though. Please help me. Thank you.

Work Gear for Electricians and the Trades
Re: Subpanel Calculation #32852 01/04/04 06:16 PM
Joined: Dec 2003
Posts: 751
E
earlydean Offline
Member
You got the cart before the horse. First, you compute the combined loads, using diversity factors allowed by the NEC. Second, you choose a panel of a size adequate for the loads just computed. Third, you choose a feeder of ample size. Fourth, you choose a circuit breaker sized to protect the feeder and panel.

Or, take the shortcut: size the breaker for the size of the new panel (usually 100 or 60 Amps)and feed with 100 or 60 Amp wires.


Earl

Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
HCE727
HCE727
Delaware County, PA, USA
Posts: 186
Joined: November 2005
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 19
Admin 8
Popular Topics(Views)
278,832 Are you busy
211,988 Re: Forum
199,034 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3