New Subpanel In Garage

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  #1  
Old 09-22-13, 08:56 AM
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New Subpanel In Garage

For a number of reasons, I am considering adding a subpanel to our garage. Currently, electrical in the garage (overhead door, some receptacles, and lights) are all fed off a 20amp run from one of the subpanels in our house. Main reason for adding a subpanel is that we will soon do a major back yard remodel, and will almost certainly need a new 240v circuit for the pool pump put in. It's going to be much more straightforward to do that if we already have a 60 amp subpanel in the garage. Would also be a nice opportunity to eliminate the existing 20 amp feed, which comes through a covered walkaway. Oh and of course this way I could buy a Tesla and be able to charge it. (Kidding on that.)

I will not be doing the work myself; just researching my options.

We have 200 amp service, which feeds into 2 each 100 amp subpanels. So no can do to subpanel off the main. However, possibly the garage subpanel could be fed from one of the 100 amp breaker boxes. Does that seem reasonable? I attahed a photo of the breaker box under consideration. In the lower right hand corner is an old 30 amp breaker for a decommissioned electric dryer....I'm wondering if that gives me enough space for a breaker for a new subpanel. Are any of you able to make a decent guess by looking at the attached?
 
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Old 09-22-13, 09:53 AM
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Would also be a nice opportunity to eliminate the existing 20 amp feed, which comes through a covered walkaway.
Here if the walkway is attached at both ends even if not enclosed that makes it an attached garage. Local code could vary. Wiring for an attached garage is slightly different from wiring for a detached garage.

In the lower right hand corner is an old 30 amp breaker for a decommissioned electric dryer.
The space required for a 60 amp breaker is the same as for a 30 amp (or even a 100a). Suggestion If both boxes are full you may want to future proof by replacing one of them with a box with more spaces. You seem to have a lot of half breakers in the box. Can you give us the model number of the box in the picture. There should be a number in the model number such as Q0612 .
 
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Old 09-22-13, 10:05 AM
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QOC12 is the model, I think...
 
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Old 09-22-13, 12:00 PM
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QOC12 is the model, I think...
I'd guess you got that number inside the panel door and that it is the catalog number of the cover and door which was sold separately. The panel catalog number, if you can find it, should be inside the panel box. That looks to be a Square D QO series panel from the mid to late '70s. The old style tandem breakers is a dead giveaway on that. Regardless, you could still replace it with a larger panel.

In the lower right hand corner is an old 30 amp breaker for a decommissioned electric dryer....I'm wondering if that gives me enough space for a breaker for a new subpanel.
Ray told you correctly, a 60A 2P breaker (QO260) takes the same two spaces as a 30A 2P breaker (QO230).
 
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Old 09-22-13, 12:54 PM
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We have 200 amp service, which feeds into 2 each 100 amp subpanels. So no can do to subpanel off the main.
Why not? The question isn't what size the breakers in the panel are, it's what load is being drawn. It's difficult to tell from your picture, but it looks like the branch circuit protection devices in this panel add up to 300A, and it's doing fine.

If you're already drawing 200A, total, for your house, then you're out of capacity and it's time to upgrade your service. If you're not, you can feed a new subpanel from any box that has the capacity available. Doing a residential load calculation on each panel will give you that answer.
 
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