An interesting question just came up that I can't answer.

A field service rep at my facility today was servicing our equipment and took a call from another customer. The other customer's equipment is on a 220 volt service with a double pole breaker labeled 20 Amp on each pole.

Evidently there has been an ongoing problem with this breaker. The equipment in question is rated for 40 amp service.

I'm no electrician i.e. building power distribution and wiring, but I do understand that in the US 220 volt circuits are fed out of phase with two parallel 110 volt legs. My understanding was that 20 amps drawn from either leg would trip the breaker in unison since they are connected.

But the question that came up, is this considered a 40 amp service or 20 amp service? Is the rating of the breaker the COMBINED rating or the max rating for either leg?

So, if I were looking at a breaker with two poles, each labeled "20", how many amps on either leg would trip the breaker, 10 or 20?

This is important to understand based on the rating of the equipment. It is foreign manufactured for European standard 220 volts, which is single phase as I understand it. I am not European, but I would assume that European breakers are single pole switches.

Thanks if you know the answer.

Edit: The reason why I mentioned the difference between European and US ratings is because if the equipment was labeled for Europeans using single phase power, then 20 amps would be literally 20 amps on a single pole switch. My thought process is that with a 2 phase system, each leg is protecting its own leg of the circuit. 20 amps drawn through either leg would trip it, so in effect the "trip current" is 20 amps....yet, lets say for discussion the load was drawing near maximum rating through each leg...would the total load of the service be around 40 amps?

It confuses me because we aren't talking about parallel legs from the same voltage source, thus all currents add together. We are talking about two voltages fed out of phase. My logic says that the total current would STILL be the sum of each phase leg, but I don't fool with 220 AC very much so I'm confused.

A field service rep at my facility today was servicing our equipment and took a call from another customer. The other customer's equipment is on a 220 volt service with a double pole breaker labeled 20 Amp on each pole.

Evidently there has been an ongoing problem with this breaker. The equipment in question is rated for 40 amp service.

I'm no electrician i.e. building power distribution and wiring, but I do understand that in the US 220 volt circuits are fed out of phase with two parallel 110 volt legs. My understanding was that 20 amps drawn from either leg would trip the breaker in unison since they are connected.

But the question that came up, is this considered a 40 amp service or 20 amp service? Is the rating of the breaker the COMBINED rating or the max rating for either leg?

So, if I were looking at a breaker with two poles, each labeled "20", how many amps on either leg would trip the breaker, 10 or 20?

This is important to understand based on the rating of the equipment. It is foreign manufactured for European standard 220 volts, which is single phase as I understand it. I am not European, but I would assume that European breakers are single pole switches.

Thanks if you know the answer.

Edit: The reason why I mentioned the difference between European and US ratings is because if the equipment was labeled for Europeans using single phase power, then 20 amps would be literally 20 amps on a single pole switch. My thought process is that with a 2 phase system, each leg is protecting its own leg of the circuit. 20 amps drawn through either leg would trip it, so in effect the "trip current" is 20 amps....yet, lets say for discussion the load was drawing near maximum rating through each leg...would the total load of the service be around 40 amps?

It confuses me because we aren't talking about parallel legs from the same voltage source, thus all currents add together. We are talking about two voltages fed out of phase. My logic says that the total current would STILL be the sum of each phase leg, but I don't fool with 220 AC very much so I'm confused.

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