Dryer-Water heater OCPD

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A/A Fuel GTX

A/A Fuel GTX

Senior Member
Location
WI & AZ
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Electrician
Since a 25A circuit breaker is a standard size, why aren't they required on a typical 4500w water heater and 5000w dryer? 30's are all I ever see........
 
The breaker is installed to protect the conductors. Since we install #10 conductors which require a 30-amp breaker, that is what is installed. If you installed a conductor with an ampacity of 25-amps THEN you would need a 25-amp breaker/fuse.
 
A/A Fuel GTX said:
Since a 25A circuit breaker is a standard size, why aren't they required on a typical 4500w water heater and 5000w dryer? 30's are all I ever see........
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Don't confuse the min circuit ampacity with the max. OCP.

A standard 4500 watt heater is rated about 19 amps at 240v. Using art. 422.13 we must consider a standard water heater as being a continuous load. 19*1.25 = 24 amps. Art. 422.11(E)(3) allows us to not exceed 150% of the rated current--- 150% of 19= 28.5 amps. The same art. allows us to use the next higher standard breaker size.

There is no problem using a 25 amp breaker and it use to be that they made us do it around here.
 
iwire said:
IMO the breaker also protects the appliance.

If that is not so I see no reason at all for rules in 422.11
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I agree, Bob. I guess the fact that water heaters and dryers don't come with a protective device rating, we can get by with 30A breakers.
 
Dennis Alwon said:
Don't confuse the min circuit ampacity with the max. OCP.

A standard 4500 watt heater is rated about 19 amps at 240v. Using art. 422.13 we must consider a standard water heater as being a continuous load. 19*1.25 = 24 amps. Art. 422.11(E)(3) allows us to not exceed 150% of the rated current--- 150% of 19= 28.5 amps. The same art. allows us to use the next higher standard breaker size.

There is no problem using a 25 amp breaker and it use to be that they made us do it around here.
Click to expand...

I can see that applying to water heaters but not dryers.
 
haskindm said:
The breaker is installed to protect the conductors. Since we install #10 conductors which require a 30-amp breaker, that is what is installed. If you installed a conductor with an ampacity of 25-amps THEN you would need a 25-amp breaker/fuse.
Click to expand...

Are you saying I can not use a 25A CB w/#10's in the OPs scenarion?
 
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