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Old 08-19-2014, 12:38 PM   #1
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Main Disconnect in Subpanel


Can I use a 100 AMP main disconnect for a sub panel as a main disconnect?

My garage will have 8 breakers for a sub panel and a ufer ground.
The main panel has a 50 AMP breaker to feed the sub panel. From what I understand there has a main disconnect local to the garage but I can't find anything cheap to buy and easy to install except a 100 AMP main disconnect switch.
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Old 08-19-2014, 12:51 PM   #2
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The main can serve as the disconnect. Make sure the feeder conductor is in the correct range of wires acceptable for the lugs.
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Old 08-19-2014, 03:44 PM   #3
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Quote:
Originally Posted by Lightboxes View Post
Can I use a 100 AMP main disconnect for a sub panel as a main disconnect?

My garage will have 8 breakers for a sub panel and a ufer ground.
The main panel has a 50 AMP breaker to feed the sub panel. From what I understand there has a main disconnect local to the garage but I can't find anything cheap to buy and easy to install except a 100 AMP main disconnect switch.
What panel are you using for the sub-panel .. make and model .. ? It is possible you may be fine if you configure it correctly.
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Old 08-19-2014, 04:03 PM   #4
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It's from Home Depot. There's a space for the disconnect right at the top or bottom. I thought I could use this space for a convenient disconnect.

Home Depot website:
Model # HOM1224L125VP
Internet # 202529821
Store SKU # 860934

w w w .
homedepot.com/p/Square-D-by-Schneider-Electric-Homeline-125-Amp-12-Space-24-Circuit-Indoor-Main-Lugs-Load-Center-with-Cover-Value-Pack-HOM1224L125VP/202529821
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Old 08-19-2014, 05:16 PM   #5
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That panel is service rated and would allow you to use the 6 disconnect rule. The knockout at the top center is for a main breaker if needed.

You say 8 breakers so the applied rule is no more than six throws of the hand to disconnect all power to the building/structure. So if 2 of your circuits require 240 volts these would require two double pole breakers then if you add 4 single pole 120 volt circuits that would be 6 throws. This would be allowed as the disconnect.
Another configuration would be 6 full size single pole breakers
Another would be 3 tandem single pole breakers

Once you exceed 6 single throws of the hand to disconnect all power you would need a main breaker in the panel.

If your running 8 120 volt circuits then you would need a main disconnect either in the panel or remote to the panel.

I am also assuming from your description this garage is detached from the home.
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Old 08-19-2014, 05:19 PM   #6
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Install a 2 pole 60 amp breaker and back feed your panel and install a hold down kit.
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Old 08-19-2014, 05:44 PM   #7
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Install a 2 pole 60 amp breaker and back feed your panel and install a hold down kit.
Wirenut

I thought the same ... but I can't find the hold down kit for that panel in my books. Hom4RK2LA might be it. The panel has the knockout for a main breaker though.
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Old 08-19-2014, 05:54 PM   #8
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Quote:
Originally Posted by Stubbie View Post
If your running 8 120 volt circuits then you would need a main disconnect either in the panel or remote to the panel.
Yeah, garage is detached. I wanted to put in a main disconnect right in that panel spot but I was surprised I didn't see anything simple (like a switch) on the Internet. Rather, it's a 100 AMP minimum size type disconnect. I guess I can just use the 100 AMP disconnect as a switch?

I understand the options, disconnect outside the box, less breakers, or even the 60 Amp breaker tying back in but I'll use those options if I have to. Since I'm new to all this (building my own garage by the way) I wanted to avoid complications, keep it simple so it will pass a review by the inspector and licensed electrician.
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Old 08-19-2014, 06:24 PM   #9
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http://static.schneider-electric.us/...1100HO9902.pdf
I think the hold down kits are for panels with "convertible mains.
Not sure if his panel is.
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Old 08-19-2014, 06:26 PM   #10
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Quote:
Originally Posted by Lightboxes View Post
Yeah, garage is detached. I wanted to put in a main disconnect right in that panel spot but I was surprised I didn't see anything simple (like a switch) on the Internet. Rather, it's a 100 AMP minimum size type disconnect. I guess I can just use the 100 AMP disconnect as a switch?

I understand the options, disconnect outside the box, less breakers, or even the 60 Amp breaker tying back in but I'll use those options if I have to. Since I'm new to all this (building my own garage by the way) I wanted to avoid complications, keep it simple so it will pass a review by the inspector and licensed electrician.
You can bolt in a 100 amp main for that panel but just seems redundant and extra cost.

You can use the 100 amp disconnect as a switch if I understand you correctly. As a technicality it needs to be service rated and will say on the inside spec sheet. Not sure all inspectors would enforce that requirement.
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Old 08-19-2014, 06:52 PM   #11
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Quote:
Originally Posted by wirenut1110 View Post
http://static.schneider-electric.us/...1100HO9902.pdf
I think the hold down kits are for panels with "convertible mains.
Not sure if his panel is.
My books show it is a convertible main/MLO so the HOM4RK2LA should be the correct holddown.
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Old 08-19-2014, 09:00 PM   #12
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Okay...Cool! A hold down kit. I'll look into that. I didn't know you could use something like this. Again, it's new to me and I'll look into it. THANKS SO MUCH FOR THE HELP!
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