Is the circuit breaker amperage the rms amperage

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SUMMARY

The discussion centers on the relationship between circuit breaker amperage ratings and RMS (Root Mean Square) voltage. Circuit breakers rated at 15A are designed to trip based on RMS current, which reflects the heating effect of the current. The referenced datasheet indicates that circuit breakers operate on RMS symmetrical current, meaning the 15A rating corresponds to the effective current that would produce the same heating as a DC current of the same value. Therefore, if a 10-ohm resistor were connected, the breaker would trip if the current exceeds the rated RMS value.

PREREQUISITES
  • Understanding of RMS voltage and current concepts
  • Familiarity with circuit breaker operation and ratings
  • Basic knowledge of electrical resistance and Ohm's Law
  • Ability to interpret electrical datasheets and graphs
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  • Research "RMS current" and its implications in electrical systems
  • Study the operation principles of thermal circuit breakers
  • Examine the Schneider Electric circuit breaker datasheet for detailed specifications
  • Learn about the relationship between voltage, current, and resistance using Ohm's Law
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Electrical engineers, electricians, and anyone involved in residential electrical systems or circuit protection design will benefit from this discussion.

Puglife
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The circuit breakers of my house say that they are 15a (the majority of them). The rms voltage is 120v for the outlets, and so the peak voltage is about 170v. I was wondering, if I hypthetically connected the terminals together with a 10 ohm resistor, would the breaker trip? I don't know if the amperage drawn is total amps, or amps at the rms voltage, and so that is what I am asking. I know its not safe to do, and I am not going to do it, but I would like to know if it is 15a in general or at the rms, allowing for more amperage at its peak voltages. Thank You.
 
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Grinkle said:
http://static.schneider-electric.us/docs/Circuit Protection/Molded Case Circuit Breakers/0100-400 A Frame FA-LA/FA-FC-FH/0600DB0105.pdf

Look at page 2, it has a curve of time at rated current vs trip time. A circuit breaker will take approx 1000 seconds to trip if the current is right at the rated value, according to this graph at least.
Im not exactly sure what it is saying, because no current will be consistantly be drawn out of the outlet, because many times a second, the voltage reaches zero, and thus so is the current.
 
Puglife said:
Im not exactly sure what it is saying, because no current will be consistantly be drawn out of the outlet, because many times a second, the voltage reaches zero, and thus so is the current.

Puglife said:
I don't know if the amperage drawn is total amps, or amps at the rms voltage, and so that is what I am asking.
The datasheet Grinkle linked describes RMS symetrical current.

Look up "RMS current"
then think about it - fuses amd thermal breakers work by heating an element.
Not surprising they'd be rated in terms of "heating value" of current, would you think ?
 
Thanks, Jim - yes, RMS.
 
Grinkle said:
Thanks, Jim - yes, RMS.
Thank You Both!
 

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