Two pole breaker/ 240v question


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Old 10-12-17, 05:44 PM
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Two pole breaker/ 240v question

If you have a 40 Amp Two-Pole Circuit Breaker...

What is the individual amp rating for each individual breaker?

Essentially, what is the maximum amperage supplied to the end device? 40 amps or 80 amps?

Also, what is the difference between 220v, 225v and 240v?
 
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Old 10-12-17, 06:40 PM
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The rating is not doubled each pole of the breaker protects the wire connected to it. If for example it is #8 wire then each wire needs to be protected by a 40a breaker and total amount of current is 40 amp maximum.
 
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Old 10-12-17, 06:41 PM
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A two pole 40A breaker supplies 40A to a 240v circuit.

Many years ago.... our power was 110v/220v.
It is now 120v/240v.

No idea where 225v came from.
 
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Old 10-12-17, 06:42 PM
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A breakers rating is the current at which it will trip if any leg is over that number. In the case of the 40 amp breaker, if either leg draws over 40 amps, it will trip. The max amps allowed is 40 amps. (One thing to note is standard breakers are inverse time devices. Meaning that the higher the current is over a breakers rating, the faster it will trip.)

Also, what is the difference between 220v, 225v and 240v?
Nothing. Voltage is nominal and according to the NEC that standard voltage is 240 volts. Other standard voltages are 120,208,277,347,480, and 600.
 
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Old 10-13-17, 07:05 AM
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A 40A two pole breaker is 40A at 240V or effectively 80A at 120V (40A per leg @ 120V)
 
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Old 10-13-17, 01:08 PM
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I'm confused by what is effectively 80a.@120v.
 
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Old 10-13-17, 01:14 PM
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A 40A 240V circuit provides two legs of 120V each capable of 40A. Assuming the load was perfectly balanced between the two 120V legs, you could power 80A (40A + 40A) worth of 120V loads from that circuit.
 
 

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