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  #1  
Old 10/2/12, 5:34 AM
Joshua L. Frederick Joshua L. Frederick is offline
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Default 20 amp breaker for water heater

20 amp breaker, with 10 gauge wire, installed on 50 gal. Whirlpool heater (upper left breaker).

Comments?

Thanks in advance.
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  #2  
Old 10/2/12, 8:05 AM
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Default Re: 20 amp breaker for water heater

Probably too small but what is the heater wattage?
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Old 10/2/12, 8:08 AM
Joshua L. Frederick Joshua L. Frederick is offline
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Default Re: 20 amp breaker for water heater

Quote:
Originally Posted by Robert Meier View Post
Probably too small but what is the heater wattage?
I'm assuming 4500, no? Isn't that typical for newer, 50 g electric? Not 100% sure, though.
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Old 10/2/12, 8:38 AM
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Default Re: 20 amp breaker for water heater

If it's 4500 then the 20 amp will work but it won't be code compliant. A water heater of this type is required to be considered a continuous load meaning that the branch circuit needs to be calculated at 125% of the heater's rated ampacity.

4500/240 = 18.75 amps, will work on a 20 amp OCPD but,
18.75*125% = 23.4 amps, requires a 25 or 30 amp circuit.
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  #5  
Old 10/2/12, 2:53 PM
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Mary Ann Chiquete Mary Ann Chiquete is offline
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Default Re: 20 amp breaker for water heater

Quote:
Originally Posted by Robert Meier View Post
If it's 4500 then the 20 amp will work but it won't be code compliant. A water heater of this type is required to be considered a continuous load meaning that the branch circuit needs to be calculated at 125% of the heater's rated ampacity.

4500/240 = 18.75 amps, will work on a 20 amp OCPD but,
18.75*125% = 23.4 amps, requires a 25 or 30 amp circuit.
Great information Robert, thanks.





Mary Ann Chiquete
Serving the entire Phoenix Metro Area
623-399-7962
www.benchmarkazinspect.com

benchmarkaz@gmail.com

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  #6  
Old 10/2/12, 3:10 PM
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Christopher Currins Christopher Currins is offline
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Default Re: 20 amp breaker for water heater

Here's a good link, I like it anyway.

How to figure Volts-Amps-Watts for residential water heater






CBC HOME INSPECTIONS

Christopher Currins
Professional Home Inspector In Edwardsville, Glen Carbon, Godfrey, Maryville,
Fairview Heights, O'Fallon and surrounding areas of S
outhern Illinois

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  #7  
Old 10/2/12, 3:30 PM
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Default Re: 20 amp breaker for water heater

Quote:
Originally Posted by mchiquete View Post
Great information Robert, thanks.

You're welcome, here's a few NEC sections to accompany my last post:

Quote:
422.11 Overcurrent Protection. Appliances shall be pro-
tected against overcurrent in accordance with 422.11(A)
through (G) and 422.10.
(E) Single Non–motor-Operated Appliance. If the branch
circuit supplies a single non–motor-operated appliance,
the rating of overcurrent protection shall comply with the
following:
(1) Not exceed that marked on the appliance.
(2) Not exceed 20 amperes if the overcurrent protection
rating is not marked and the appliance is rated
13.3 amperes or less; or
(3) Not exceed 150 percent of the appliance rated current if
the overcurrent protection rating is not marked and the
appliance is rated over 13.3 amperes. Where 150 per-
cent of the appliance rating does not correspond to a
standard overcurrent device ampere rating, the next
higher standard rating shall be permitted.
Quote:
422.13 Storage-Type Water Heaters. A fixed storage-type
water heater that has a capacity of 450 L(120 gal) or less shall
be considered a continuous load for the purposes of sizing
branch circuits.
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  #8  
Old 10/3/12, 6:38 AM
Joseph M. Whitt Joseph M. Whitt is offline
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Default Re: 20 amp breaker for water heater

My 40 gallon has been on a two pole 20 for more than 5 years with no problem.



Mike Whitt
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  #9  
Old 10/3/12, 9:23 AM
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James T. McGrail James T. McGrail is offline
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Default Re: 20 amp breaker for water heater

Great link !
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