30,000 watt water heater ?

[Buck Parrish]

This water heater has on the name plate 30,000 watt, 240 V, 3 phase
What size conductor and breaker size would you use?
Their is 3 phase in the building.
Thanks for any input.

 

[charlie b]

30,000 watts divided by 240, and divided again by 1.732 (the square root of three) gives you 72.2 amps. Add 25% (water heaters are considered "continuous loads"), and you get 90.2 amps. I would use #3 conductors, and a 100 amp breaker.

 

[broadgage]

The loading of 30 KW suggests to me that this is an on demand water heater, not a storage type.
If it is an on demand type than I believe that it could be considered non continous, after all no one would run the hot tap for more than three hours surely?
If it is an exceptionaly large storeage type water heater, then I would agree that it is a continous load, and that the circuit ampacity should be increased by 25%

 

[Buck Parrish]

Thanks,
It is a storage type.
The thing has got huge lugs on it for terminating. 100 amps sounds good to me.