Originally Posted By: jremas This post was automatically imported from our archived forum.
Appliances that are permanently connected and rated over 300V-A must have a means of disconnect “within sight” of the appliance. So,… if the water heater is in the basement and the main panel that feeds the water heater circuit is in the garage on the 1st floor, would a disconnect within sight of the appliance be required for a 40gallon, 240v, 1500 watt water heater?
BTW, the hypothetical water heater I used as an example would only heat the water to 120 deg. F at a rate of 7.8 gallons per hour(in the north). So yeah I know it is undersized.
After you answer that, what size should the circuit breaker be?
Hmmmmmm. 2nd question is not that easy is it?
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Jeff Remas
REMAS Inspections, Inc.
Northeastern PA & the Poconos
www.NEPAinspector.com
Originally Posted By: rmoore This post was automatically imported from our archived forum.
Jeff…you are the tricky one!
It's in sight OR capable of being locked in the open position. As most breakers can be fitted with a lock-out I say no problem.
Second part...Should not exceed 20 amp, although in this case, with your horribly underpowered 6.25 amp water heater 15amp would be more appropriate. Even better..get a new heater!
Originally Posted By: Bob Badger This post was automatically imported from our archived forum.
Jeff does this water heater exist?
If no overcurrent device is indicated on the water heater we need to look at 422.11(E) this unit being under 13.3 amps it will be section 422.(E)(2)
Quote:
If the overcurrent protection rating is not marked and the appliance is rated 13.3 amperes or less, not exceed 20 amperes;
As Richard stated a 20 amp circuit is acceptable.
This circuit would have to have a minimum ampacity of 7.8 amps (125% of 6.25)
Any overcurrent device above 7.8 and up to 20 amps would be compliant.
The smallest allowable conductor would be a 14 AWG.
If this water heater was 13.3 amps or above the maximum overcurrent would be covered by 410.11(E)(3)
Quote:
If the overcurrent protection rating is not marked and the appliance is rated over 13.3 amperes, not exceed 150 percent of the appliance rated current. Where 150 percent of the appliance rating does not correspond to a standard overcurrent device ampere rating, the next higher standard rating shall be permitted.
The disconnect is a tricker it will depend on the AHJs interpretation of "capable of being locked in the open position".
Some AHJs accept that you can put a LOTO device on any breakers when needed others want one permanently installed at the time of inspection.
At 6.25 amps a $2.00 two pole toggle switch at the unit would be cheaper than the LOTO device. 
Originally Posted By: jremas This post was automatically imported from our archived forum.
Boy, you guys are good. Not too fair to bring the big guns out too early huh? I knew you sparky whackers would jump all over this one before any regular joe inspectors had a chance.
Good job, especially not knowing if the breaker was designed to be locked in the off position.
No, this heater does not exist, I just made up the numbers to throw off someones calculations.
Thanks..
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Jeff Remas
REMAS Inspections, Inc.
Northeastern PA & the Poconos
www.NEPAinspector.com
Originally Posted By: Bob Badger This post was automatically imported from our archived forum.
jmyers wrote:
If you have a 240 volt 3800 watt water heater, typically you would protect it with a 20 amp cb (double pole) and #12 wire.
3800 / 240 = 15.8 amps.
The minimum circuit ampacity is 125% of this. [422.13]
15.8 x 1.25 = 19.75
The maximum circuit ampacity is 150% of 15.8 amps. [410.11(E)(3)]
15.8 x 1.5 = 23.7 amps
410.11(E)(3) allows moving up to the next standard breaker.
The next standard breaker from 23.7 amps is a 25 amp breaker. [240.6(A)]
For this water heater a 20 amp breaker with a 12 AWG or larger conductor is compliant
Or a 25 amp breaker with 10 AWG or larger conductor is compliant.
jmyers wrote:
What happens if you protect it with a 30 amp cb (double pole) and #10 wire?
The 10 AWG is fine but the 30 amp breaker is a violation of 410.11(E)(3).
You can always use larger conductors than necessary, I have had to feed 20 amp receptacles on a roof (commercial) with 4 AWG.
If we want to keep voltage drop less than 3% for this water heater, 12 AWG could go 114 feet, use 10 AWG and this increases to 190 feet.  (One way circuit length)
