Standard breaker size

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hhsting

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Glen bunie, md, us
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Junior plan reviewer
I installed 4.5kw, 277V, single phase water heater with branch circuit breaker size of 30A.

Inspector flagged it and says should be 25A.

I cannot find 25A circuit breakers. All sizes found are 20 or 30A. Does anyone know of any? Are they hard to find? Does nec 2014 article 240.6 standard overcurrent sizes apply to fuses and certain type of breakers?
 

hhsting

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Location
Glen bunie, md, us
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Junior plan reviewer

shortcircuit1

Senior Member
Location
USA
I installed 4.5kw, 277V, single phase water heater with branch circuit breaker size of 30A.

Inspector flagged it and says should be 25A.

I cannot find 25A circuit breakers. All sizes found are 20 or 30A. Does anyone know of any? Are they hard to find? Does nec 2014 article 240.6 standard overcurrent sizes apply to fuses and certain type of breakers?

Look at 420.11(E) for over current protection. If you have a over current protection marked on the water heater use that as your OCPD if not you have to multiply your amps x 1.5 if your amps are more than 13.3A and no over current marking on the device.If it doesnt correspond to standard OCPD you can select the next size up. In your case 4500/277=16.25x1.5=24.36 and next standard size is 25A.
 

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
Look at 420.11(E) for over current protection. If you have a over current protection marked on the water heater use that as your OCPD if not you have to multiply your amps x 1.5 if your amps are more than 13.3A and no over current marking on the device.If it doesnt correspond to standard OCPD you can select the next size up. In your case 4500/277=16.25x1.5=24.36 and next standard size is 25A.
420.11(E) applies to appliance like toaster etc not to water heater.

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tw1156

Senior Member
Location
Texas
Look at 420.11(E) for over current protection. If you have a over current protection marked on the water heater use that as your OCPD if not you have to multiply your amps x 1.5 if your amps are more than 13.3A and no over current marking on the device.If it doesnt correspond to standard OCPD you can select the next size up. In your case 4500/277=16.25x1.5=24.36 and next standard size is 25A.

My experience has been a water heater this size would meet the 422.13 requirement and only be permitted to be sized at 125%. Nonetheless, it still calculates to the 25A OCPD, but you can see how it might change depending on what number you plug in.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
Fact: While 25 amps is a standard breaker size, it is not available in all breaker configurations, for example a Square D QOB 10KAIC is available, but a 22KAIC one is not. They are not available in an GFCI configuration in many panels. When you run in to that, it stinks. You basically have to install a fused disconnect in lieu of a breaker. I have usually had success in passing the cost for this on with the proper argument.
 

don_resqcapt19

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Location
Illinois
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retired electrician
420.11(E) applies to appliance like toaster etc not to water heater.

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There is nothing that says an appliance is a typical kitchen appliance. A water heater is an appliance and is covered by 422.11(E).
 

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
There is nothing that says an appliance is a typical kitchen appliance. A water heater is an appliance and is covered by 422.11(E).
Oh yea well how come water heater manufacturer list minimum circuit breaker size per NEC 2014 Article 422.13 but never maximum circuit breaker size manufacturer instruction?

If NEC 2014 Article 422.11(E) apply to water heater then manufacturer should also list maximum size per 422.11(E) but they never do and so thats a hint 422.11(E) does not apply to water heaters.
If it did it would be on manufacturer instruction.
 

david luchini

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Staff member
Location
Connecticut
Occupation
Engineer
If NEC 2014 Article 422.11(E) apply to water heater then manufacturer should also list maximum size per 422.11(E) but they never do and so thats a hint 422.11(E) does not apply to water heaters.
If it did it would be on manufacturer instruction.

422.11 doesn't say anything about manufacturers' markings, so lack of a marking of maximum breaker size would not be evidence that a water heater isn't an appliance with regards to Art. 422.

More pertinent would be that "water heater" is specifically mentioned in 422.11(F)(3) and 422.13. A water heater is an appliance, and is subject to the Art 422 requirements.
 

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
422.11 doesn't say anything about manufacturers' markings, so lack of a marking of maximum breaker size would not be evidence that a water heater isn't an appliance with regards to Art. 422.

More pertinent would be that "water heater" is specifically mentioned in 422.11(F)(3) and 422.13. A water heater is an appliance, and is subject to the Art 422 requirements.
Ok is it subject to nec 2014 article 422.11(E)(3)? Where is manufacturer marking stated on article 422.13 but thats still provided?

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hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
Just follow the Code. It tells you what the min and Max breakers can be.
Ok but the question still remains manufacturer wont list in water heater manucturer instruction bkr size Article 422.11(E)(3) and why? Does it not apply? If it applies then why not list it?

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