house electrical service question - Electronic Circuits Projects Diagrams Free

jrz126 · 12th April 2005, 11:05 PM

My dad and I are looking into upgrading our electrical service, we currently have a 100 amp service, and we're going up to 200 amps.
Does this mean 200 amps per leg (400A total)?

We're kinda confused though, the main breaker on the new panel has 4 breakers with a common trip. each breaker has a 200 amps printed on it, so does this mean it's capable of 400 amps per leg?

Dean Huster · 13th April 2005, 12:26 AM

200 amp service implies 100 amps per 120-volt leg or 200 amps total. A 240 volt load would draw an equal amount from both legs, e.g., 30 amps, leaving 70 amps in each leg for other loads.

Just because a panel may be rated for 1000 amps doesn't mean that you have 1000 amp service provided by the utility. You're ultimately limited by the size of the transformer they supply and you have to derate accordingly if that transformer is being shared by other households.

That is a bizarre main breaker. Main service interrupts are usually a single 240-volt breaker or a ganged dual 120-volt pair. By "common trip", do you mean that all four are mechanically linked so that if one trips, they all trip?

Dean

jrz126 · 13th April 2005, 01:31 AM

The main breaker has a bar going across all 4 switches and it says "common int. trip." There is also a rating of 22kAIc (Amperage Interuption Current).
The box for the panel said 200A main breaker, 40 circuits max.

Could the 200A mean 200A for the entire combination of breakers? If thats the case though, why would the 200A be printed on each breaker?

My dad talked to the power company, they said we already have a 200A service coming up to the meter and a 200A meter itself. so we sould be good to go.

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12th April 2005, 11:05 PM	(permalink)
jrz126	house electrical service question My dad and I are looking into upgrading our electrical service, we currently have a 100 amp service, and we're going up to 200 amps. Does this mean 200 amps per leg (400A total)? We're kinda confused though, the main breaker on the new panel has 4 breakers with a common trip. each breaker has a 200 amps printed on it, so does this mean it's capable of 400 amps per leg? __________________ Jeff To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be.

13th April 2005, 12:26 AM	(permalink)
Dean Huster	200 amp service implies 100 amps per 120-volt leg or 200 amps total. A 240 volt load would draw an equal amount from both legs, e.g., 30 amps, leaving 70 amps in each leg for other loads. Just because a panel may be rated for 1000 amps doesn't mean that you have 1000 amp service provided by the utility. You're ultimately limited by the size of the transformer they supply and you have to derate accordingly if that transformer is being shared by other households. That is a bizarre main breaker. Main service interrupts are usually a single 240-volt breaker or a ganged dual 120-volt pair. By "common trip", do you mean that all four are mechanically linked so that if one trips, they all trip? Dean __________________ Dean Huster, Electronics Curmudgeon Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines). R.I.P.

13th April 2005, 01:31 AM	(permalink)
jrz126	The main breaker has a bar going across all 4 switches and it says "common int. trip." There is also a rating of 22kAIc (Amperage Interuption Current). The box for the panel said 200A main breaker, 40 circuits max. Could the 200A mean 200A for the entire combination of breakers? If thats the case though, why would the 200A be printed on each breaker? My dad talked to the power company, they said we already have a 200A service coming up to the meter and a 200A meter itself. so we sould be good to go. __________________ Jeff To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be.