Sub panel cable selection help

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Old 08-01-15, 10:06 AM
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Sub panel cable selection help

Hello,
New to the forum. I recently started remodeling my detached garage. Now I'm ready to wire and need some help with cable selection. I know how to wire Breaker boxes and recept.

I would like to connect into my breaker box of my house that has a 200amp feed. I have to run the feeder wire to the garage about 120 feet or so. I guest the biggest load I would have on the garage is running a 240volt sick welder. I guess my question is should I use a main breaker in the sub panel of the garage or not and if not what size breaker should I use in the main panel to safely run the garage. Also suggestions on cable size to run as a feeder to the garage.
 
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Old 08-01-15, 10:50 AM
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Welcome to the forums.

You could set yourself up with a 60A 240v subpanel or 100A if you feel you need a lot of power.
The breaker in your main panel will be determined by your subpanel size.

Are you going to run conduit/PVC or direct burial ?
What is the amperage requirement of the welder ?
 
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Old 08-01-15, 11:15 AM
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Thanks pete for the welcome and responce

Sorry PJMAX got confused on my post, (for Pete in the Title) Well to be honest I don't have the stick welder yet. So that just a future thinking just trying to plain ahead a little. I currently have a flux wire that uses 120 volts at 20A form the wall. As for the feeder cable direct burial what I'm thinking and conduit only were it exits the ground and into the walls.
 

Last edited by eddiep1966; 08-01-15 at 11:26 AM. Reason: wrong name in title
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Old 08-01-15, 11:37 AM
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my question is should I use a main breaker in the sub panel of the garage or not
Any time you have more then six breakers in a panel in a detached building you must have a disconnect. A main breaker makes a convenient disconnect. The lowest priced panels are often main breaker kits that come with not just a main breaker but an assortment of branch circuit breakers. A 100 amp breaker kit therefore makes since price wise even if it is overkill. Since the main breaker is used only as a disconnect switch it can be larger then the main panel breaker feeding the subpanel.
and if not what size breaker should I use in the main panel
Size of breaker is determined by the size of the wire. As noted not the size of the subpanel main breaker (so long as the feed doesn't exceed the subpanel amp rating). Wire size is determined by the breaker in the main panel.
As for the feeder cable direct burial what I'm thinking
Conduit has the advantage of allowing you to easily increase power should you ever want to.
 
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Old 08-03-15, 07:43 AM
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I would use 2-2-2-4 or 2-2-4-6 MHF (Mobile Home Feeder) aluminum cable, whichever size is available in your area. It can be direct buried at 24" deep, buried in PVC conduit at 18", and run through the buildings in plastic or metal conduit. It cannot run through the building without conduit. The conduit size should be 1.5". This size cable is good for up to 90A, which should be plenty for a home workshop / garage. If you buy it at a big box store they may advertise it as a 100A cable, but that is only under specific circumstances that don't apply in your case. You will also need to get some non-oxidation grease (NoAlOx) for terminating the aluminum wires on the breaker and panel lugs.

At the house, I would install a 90A double pole breaker to feed the garage. In the garage, I would install a 100A main breaker panel with about 20 breaker spaces. You can buy these in a kit that come with the main breaker and a few other misc breakers for just about the same price as a panel without a main breaker. You'll need a ground bar kit for this panel, a ground rod, an acorn clamp, and 10-15' bare #6 copper to connect the ground rod to the garage panel ground bar.
 
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