3ph 480v wrt htr
- Thread starter timmer
- Start date
- Location
- New Jersey
- Occupation
- Journeyman Electrician
3500/480/1.73=4.2 amps. 15 amp circuit. I'm surprised that such a small heater is 3 phase.
A 3,500 watt heating element feed from 480 volts three phase would draw approximately 4.207 amps. So a 15 amp circuit breaker would easily handle it. I never came across a 6,7 or 10 amp three pole circuit breaker that would fit into conventional 480 volt three phase panels. I used to use a cheater multiplier for ruff field three phase 480 volt calculations by multiplying the KW by 1.2 . example 3.5 KW × 1.2 =4.2 Amps.
50 gallon heater
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Just out of curiosity do you have a part number?
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
Use the smallest breaker you can get, then put a fused disconnect at the water heater.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Why would you need a fused disconnect?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
422.11(E) says this unit could be on up to a 20 amp overcurrent device. If using 14 AWG conductors then the conductor is what would limit you to 15 amp overcurrent devcie.
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
I case it required protection less than the smaller breaker you could use. If it can use a MOCP device of 15A then it wouldn't be required.
Why would a water heater require any protection beyond that of the branch circuit?