Calculation question

[Matt Mckenzie]

My customer has four 240 volt, 2000 watt baseboard heaters that they want to install. The service is 120/208 three phase. What will be the actual connected load of the heaters. I am calculating P/E=I, P=I^2 x R solving for R, E/R=I, then I^2 x R= VA..... I am doing this correctly? I don't think I am I am just not seeing it. Can somebody help please?

 

[augie47]

Your 2000 watt 240 volt heaters would be about 1501 watts on 208 or 7.2 amps.
Total load would depend on which phases you use to connect.
2000* (208/240)?

 

[Smart $]

Total load would depend on which phases you use to connect.

To elaborate on that, four identical 1? loads cannot be balanced on a 3? system. He either has to have other loads unbalanced to offset, or has to compensate for the unbalance in the conductor sizing and OCPD determination... that is, if calculating a completely new supply. If an existing supply, he must determine if said supply has the capacity on a per line basis, or revise so that it does.

 

[MasterTheNEC]

7.2 A each unit if connected to 208 V , which results in about 75% output of the original 2000 W rating.