Garage subpanel question

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Old 08-15-17, 10:50 AM
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Garage subpanel question

I need to add a subpanel in my garage, it will be right next to the main panel so installation will be straight forward.

My question is, Is there any reason why I can't use a 125Amp subpanel but only service it with a 50amp breaker? I know the power will not be an issue, I just wonder if it could be a problem with someone in the future thinking it had more current?

The panel I want to use is basically for convenience, should I search and find a panel that is closer to what I intend to supply it with?

Another question I have upon closer inspection. The circuit breakers are labeled type QT. and one of them has the name I.T.E Circuit breaker. I can't find any reference to type QT breakers. I have read that I-T-E was purchased buy gould and then siemens. Does this mean I use siemens breakers in the box? I only need to replace 2 single pole breakers with the 50 amp breaker for the subpanel.
 

Last edited by nefarious; 08-15-17 at 11:39 AM. Reason: More information
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Old 08-15-17, 12:27 PM
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My question is, Is there any reason why I can't use a 125Amp subpanel but only service it with a 50amp breaker?
No problem. It is done all the time to provide the necessary spaces. Cost wise though using a 100 amp panel, save a bit, and you could still have enough spaces.
should I search and find a panel that is closer to what I intend to supply it with
No. You won't likely find a 60 amp panel with more than 6 spaces.
The circuit breakers are labeled type QT. and one of them has the name I.T.E Circuit breaker.
There should be a label inside the panel. Does it say the panel is ITE?
 
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Old 08-15-17, 01:49 PM
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There is no label on the box at all, inside or outside. I even have the sheet rock cut away from the bottom and still no label. All of the breakers that have a label are of type QT.

How does current add for circuits of different voltages? I need a circuit of 20 amp @240v and a circuit of 20 amp at 120v. My plan is for overkill and using a 50 amp breaker to fed the subpanel. I would just like to know how to calculate.
 
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Old 08-15-17, 03:09 PM
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QT is Siemens breaker and as you wrote Siemens breakers are listed for ITE.

If you add up the breakers in your home panel you will probably see the total exceeds your main breaker and that is okay because none of the circuits are probably used to capacity and at any given time and some not even in use. Same reasoning applies to a subpanel. Your subpanel should be fine when you figure actual loads. (Remember once upon a time whole houses ran on a 60 amp panel... mine still does.)
 
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Old 08-15-17, 04:40 PM
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(Remember once upon a time whole houses ran on a 60 amp panel...
And 100 years ago many houses just had a 30 amp, 120 volt panel.
 
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Old 08-15-17, 05:01 PM
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I do understand that, in my situation the two circuits, 20 amp at 240 v and 20 amp at 120 v could be on at the same time. The 20 amp 240 v is my electric brewery which will be drawing current for over an hour and the other circuit could come on at the same time. I am just curious how the current is computed when they are for different voltage.

I have two circuits that I have to move to the subpanel to make room for the subpanel breaker and the wires are not quite long enough. Do I just add the correct length and twist tie them together? Do I need to put it in a box of some sort?
 
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Old 08-15-17, 05:15 PM
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The splice can be in the panel.
 
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Old 08-15-17, 05:30 PM
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20 amp is the breaker size but what is the actual load. That is the amps you use. Lets say actual load of the 120 items is 15 amps and the load on the 240 is 16. The leg carrying the 120 volts plus one leg of the 240 load is 31 amps. The other leg carrying the 240 is only 16 so highest load would be 31 amps on one leg of the of the 50 amp breaker but your load will probably be lower.

Pros if I screwed the math just post I won't mind.
 
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