What a great site! Please be kind to me as I have done a search but sure would appreciate someone knowledgeable to confirm what I think I've already figured out.
I'm installing a subpanel in an attached garage. I've looked at the planned loads and am quite certain I will not pull more than 40A at any time.
Main service is 200A, and will require about 100' of wire to feed the subpanel.
I already have some components that I would like to use--a used, 10 year old Square D panel with a 100A main, and a 110' coil of #6 AL SER.
The feed wire will travel through the attic on a wood raceway attached to the framing, then back down the interior wall.
My concern is the wire run length. I calculate a 4.35% voltage drop for this wire run length. At less than 5%, will I be OK?
First question is whether I should protect the sub feed with a 50A or a 60A breaker in the main panel.
Second question is whether I must replace the 100A main in the subpanel with a lesser-amperage breaker. My understanding is that a subpanel doesn't even require a main disconnect, so in my mind it should not matter whether the main disconnect is 100A.
And yes, I know that the neutral must be isolated in the subpanel, and about the antioxidant stuff for the lugs.
Thanks in advance!