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View Full Version : Sub-Panel Installation


sur2baja
Jun 14, 2008, 10:33 PM
Hello All!
I currently have a 200 Amp main panel which is full. Five years ago we added a pool and the pool company added a sub-panel on the interior garage wall (back to back from the main panel). The two feeder breakers are 40 amp each. This sub-panel supplies the pool equipment and the pre-existing house circuits that the two feeder breakers replaced. Well now we added a pool kitchen and I want to add four more circuits. My thought is to replace the smaller sub-panel with a larger sub-panel and upgrade the feeder breakers appropriately. When I talked to the Home Depot guy in the electrical aisle, he suggested I forget about the feeder breakers and use a main load lug center.(?)
My understanding with this configuration, the sub-panel is connect by lugs to the main panel with a main disconnect at the new sub-panel. Then each circuit would have it's own circuit breaker. Obviously I'm a little confused but doesn't the sub-panel need feeder breakers? Can you explain the best practice on attempting my project? What is the difference between the main load and lug centers?
Thanks!

Washington1
Jun 15, 2008, 09:51 AM
You said upgrade the feeders, and breakers appropriately. Does this mean you did a demand load calculation? I say do a DLC before moving forward.

PS: I'm so sick of people saying they asked Home Depot! If you are planning to do it right, then stop asking associates working for Home depot, "TRUST ME!"

KISS
Jun 15, 2008, 12:28 PM
Something is fishy here, but to clarify some points and add enough knowledge to be dangerous:

1) Feeder breakers come from the main panel. They are two breakes ganged and known as double pole breakers and they take up usually 2 spaces.

2) Main lug panels do not have MAIN breakers.

3) Main load panels have MAIN breakers

4) Sub-panels CAN have over-rated MAIN breakers. The main breaker is used as a disconnect. They usually don't.

5) Sub-panels keep the neutral and ground busses isolated.

6) The sub-panel wire size would also have to be addressed.

7) The USUAL maximum breaker size is 100 A for branch circuits.

8) There is a way to add more 120 V circuits than spaces provided the "# of poles" specification is met with special breakers that put 2 circuits in one space.

"Me thinks" you should have the entire electrical service evaluated. e,g Demand load calculation

Washington1
Jun 15, 2008, 12:37 PM
"Me thinks" you should have the entire electrical service evaluated. e,g Demand load calculation Sounds familiar!