[Rodneyco88]

I need to power up 4, 2kW, 120v lamps. The application is to heat something up. There will be 2 lamps on top (in a reflector) and 2 on the bottom. Driven by Eurotherm controllers through SSRs. In one reflector with 2 lamps, can I run 1 leg of 208 to each lamp and connect the other end of the lamp to neutral? I don't want to run 4 each 20 amp 120v circuits, just 1, 40 amp(?? ) 208v circuit. 8kW/208=38amps, should I size the breaker at 50amps?

[tkrussell]

I do not see how a 208 Volt 40 amp feeder will solve your problem trying to feed 4- 120 volt 2kW lamps, each will draw 16.6 amps each.

Your dealing with 120 volt loads, which needs one leg of a 208 volt system, plus the neutral, to deliver 120 volts.

You need 4- 120 volt circuits, and technically, if they will run more than 3 hours, because the load amps will exceed 80% of a 20 amp circuit by 0.666 amps, you would need to run 30 amp rated circuits.

[RustyFairmount]

The math works, but my concern would be the gauge of wire you use. Consider that 240v is just two phases of 120v in a single package. Right? If you bond all lamps to the same neutral wire, will the neutral be a sufficient gauge to carry that much current?? We're talking 70amps of current on a single neutral line. 8000w/120v. I don't have a code book handy, but that's a beefy wire.

[Rodneyco88]

I believe that because the 2 hot legs are out of phase by 120 degrees that the neutral does not need to be bigger than the hot. Can someone who really knows please confirm. Thanks

[RustyFairmount]

Good point on the phase.