100 amps from a 200-amp panel

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Old 01-13-13, 03:28 PM
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100 amps from a 200-amp panel

I want to upgrade my old 100-amp fused panel to a new 200-amp breaker panel without upgrading the wires from the meter to the panel. There is a way (I've seen this done before) where you can put a 100-amp breaker right underneath the 200-amp breaker in the new panel, thus maintaining your original protection of 100 amps maximum. But, in the future, if you want to upgrade the whole system to 200 amps, you can do so simply by upgrading the outside wiring and removing that extra 100-amp breaker (without the need to change panels again). Can anyone give me instructions (or refer me to instructions) for how to add this 100-amp breaker? THANKS! Don Rockwell
 
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Old 01-13-13, 03:38 PM
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you can put a 100-amp breaker right underneath the 200-amp breaker in the new panel, thus maintaining your original protection of 100 amps maximum.
Do you mean back feeding the panel with a 100 amp breaker?
 
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Old 01-13-13, 04:11 PM
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Welcome to the forums!

That doesn't sound like a code-compliant setup.

What brand of panel are you looking at? Most manufacturers, IIRC, offer 200 amp and 100 amp panels that are essentially identical except for the size of the main breaker. I would look for a 100A that would accept a 200A main breaker in the future, or a 200A panel plus a 100A main breaker that I could install for now.

But since you need to kill the power on the feeders to make the change anyway, why not just upsize them, if needed, install a new 200A panel, and be done with it?

One more question. Why do you think 100A won't be enough for years to come? Are you planning on adding central A/C or some other major load?
 
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Old 01-13-13, 04:43 PM
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Ray, I don't know the terminology (backfeeding) but in a block diagram the 100a breaker would be between the 15a circuit breaker and the 200a main panel breaker. Nashkat, good points. I don't see a time when I would actually 'need' 200a. There's gas service in the house, so no electric stove. Could also make do with a gas clothes dryer. I was just concerned about putting in a panel today that would be obsolete in ten years. Also, it never occured to me to find a panel that would accept either a 100a or 200a breaker...that would accomplish exactly what I'm trying to do. Now that I think about it, maybe that 100a breaker I saw in the 200a panel was not a protection for the entire panel. Could be for the central ac. I do have access so I can take another look. Is 100a likely for a central ac system in a small library? THANKS for both your replies.
 
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Old 01-13-13, 05:20 PM
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A 100 amp A/C unit would be very large. A standard 2-3 ton A/C for a house might need a 30 amp circuit.
 
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Old 01-13-13, 06:00 PM
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It could have been for a subpanel. The technical point is that putting ia circuit breaker below the main breaker does not limit the panel current. Only if the main breaker is not connected and the panel is instead back fed, that is the incoming line connected directly to the 100a circuit breaker, could a 100 amp breaker on the bus bars limit power to the panel. I think you just didn't correctly understand what you saw or heard.
 
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Old 01-13-13, 08:03 PM
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Another thing for the OP to consider is that if you presently have a fuse panel you have a service that is at least 35 years old (but maybe older). Most likely the entire service including the meter socket and service entrance wiring needs to be replaced as well.
 
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