ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Happy Thanksgiving
by Bill Addiss - 11/26/20 10:34 AM
Ground fault remover :-)
by NORCAL - 11/26/20 08:13 AM
Work Gloves?
by sabrown - 11/25/20 01:54 PM
Insulated Tools: A Waste of Money?
by sabrown - 11/25/20 01:52 PM
What does your work place look like?
by Lostazhell - 11/25/20 02:56 AM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
1 registered members (Admin), 19 guests, and 20 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Subpanel Calculation #32851 01/04/04 04:56 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 05:16 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
Theelectrikid
Theelectrikid
Levittown, PA
Posts: 810
Joined: April 2004
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 9
Popular Topics(Views)
271,964 Are you busy
205,852 Re: Forum
193,926 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3