How to wire a sub panel off a sub panel
stevegold
| Posted in General Discussion on
i have a 200 amp sub panel in my house that is wired off a 200 amp main service panel outside my house. i would like to wire in a 100 amp sub panel to service a/c, a jaccuzi, etc on other side of my house (all wiring indoors). the run would be about 60′. do i just put a 100 amp breaker in the current sub, and run 3 wires (#4 copper if i am reading my book correct, black, white and green)to the new sub on the other side of the house? thanks in advance steve
Replies
Having never seen a serious A/C or spa which did not require 240v.........
You will need to run 4 wires to the new 100 amp sub-panel.
Black, red, white and insulated green in conduit (I like PVC).
Black and red = #4 copper.
White can be #6 (one size down).
Green can be #8 (two sizes down).
OR all can be #4......downsizing the neutral and ground is NEC compliant and saves a few $$.
Neutrals float in the new sub-panel (no bonding neutral / ground and box enclosure). If a bond strap or screw is supplied with the new sub-panel - do not install it; if already installed at the factory, remove it.
All of the grounds attach to a ground bar (screwed to the box enclosure) which you will most likely have to add.
Sub-panel is totally segregated - grounds on the ground bar, neutrals on the neutral bar(s). Neutrals electrically isolated from the panel enclosure. Grounds bonded to the enclosure.
FYI, I can usually buy a panel eqipped with a main breaker for less $$ than a main lug panel. Either works fine and a main breaker panel provides a disconnect at the new sub-panel
Jim
Thanks Jim:
That clears it all up!
steve