Getting 50A to detached garage

[JoeOef]

I asked a quesetion a few weeks ago about upgrading my in home panel in order to run a 100A sub to the garage. After monitoring our usage in the house and looking at what I am powering in the garage, I am considering leaving the 100A panel and putting a 50A breaker in the panel and running cable out to the garage. I have a spare 100A panel laying around.

I am planning on changing out the main breaker in the 100A panel for a 50A breaker and using that to distribute power around the garage. Two questions...Is this a terrible idea, and if not, is 2-2-4-6 mobile home feeder my best bet for wire? I know that's good for 100A but I would rather be oversized than undersized, and that seems to be the only workable wire/size I can find at my local big box hardware store that's not crazy expensive.

 

[pattenp]

You can leave the 100A main breaker in the panel, it's just a disconnect. The 50A breaker in the main service panel is the over current protection for the feeder. The #2 MHF is good to 90A, not 100A, but is an economical choice. The 50A breaker should take a max of #2, if not, up it to a 60A so the #2 will fit.

FYI - MHF needs to be in conduit where it's inside the structure.

 

[Charles (in GA)]

Attached or Detached garage?

The MHF will need to be in conduit from panel to in the ground on both ends. You can direct bury the MHF or put it in conduit from panel to panel. It cannot be exposed above ground.

there is no need to change out the main breaker in the 100 amp panel you intend to use as a sub-panel. its only purpose is to act as a disconnect for the panel. The protection for the entire circuit will be provided by the 50 amp breaker you put in the house panel to feed the garage.

Charles

 

[pattenp]

Charles, read the title.

 

[wyliesdiesels]

Since its detached dont forget 2 ground rods. And isolate the neutral bar!

 

[JoeOef]

I've got my 2 grounding rods, and I am, as a novice, assuming you are saying I need to remove any neutral-ground bond in the sub panel?

 

[pattenp]

Yes. And most likely you'll need to buy a ground bar kit for the panel unless your panel has two bars where one of them can stay bonded to the panel for the grounds.

I've got my 2 grounding rods, and I am, as a novice, assuming you are saying I need to remove any neutral-ground bond in the sub panel?