Hot Water Heater Breaker/Disconnect Size for Commercial Space

[Electricalhelp]

The incoming service is 120/208V/3P.
The Hot Water Heater says it's Input KW is 40.5kW-120/208V/3P

So please let me know if I am doing the path correctly

40500/1.73*208 = 112.42 Amp
112.42*125% = 140.52 Amp

So will I require a 150 AMP since 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.

 

[Dennis Alwon]

That is one large water heater -- assuming all elements come on at one time 150 amps seems correct

 

[raberding]

i think it's a Continuous Load if it's a Storage Tank WH. An Instantaneous WH (and to me, 40kw feels like it may be) is rated at 100%. Not 125%.
IIRC

 

[Electricalhelp]

i think it's a Continuous Load if it's a Storage Tank WH. An Instantaneous WH (and to me, 40kw feels like it may be) is rated at 100%. Not 125%.
IIRC

Could you let me know what code section you found this in?

 

[Little Bill]

Could you let me know what code section you found this in?

422.13

 

[Dennis Alwon]

i think it's a Continuous Load if it's a Storage Tank WH. An Instantaneous WH (and to me, 40kw feels like it may be) is rated at 100%. Not 125%.
IIRC

I have hooked up 3 phase water heater that was 100 amps so this could be a tank

 

[Electricalhelp]

It's a 120 Gallon all Electric Hot Water Heater

 

[raberding]

125% it is then

 

[Little Bill]

It's a 120 Gallon all Electric Hot Water Heater

Seems unnecessary, if the water is hot why do you need a heater?

 

[retirede]

Seems unnecessary, if the water is hot why do you need a heater?

Maybe he needs hotter water?

 

[raberding]

mebbe it's a

Heat Water Hotter Heater

 

[infinity]

If it was 121 gallons you could eliminate the 25% from your calculation. I'm guessing that they stop at 120 gallons.

 

[chris kennedy]

mebbe it's a

Heat Water Hotter Heater

LOL
I like it.

 

[LarryFine]

mebbe it's a

Heat Water Hotter Heater

No, silly rabbit, that's a booster.

 

[retirede]

No, silly rabbit, that's a booster.

Anything that raises the temperature could be called a booster