I have a 3 phase 240v system that reads 208 120 120 in the panel. I need to wire 4 hearing coils that read 230v 2510w and not sure how to proceed. Does anyone have some advice? It would be greatly appreciated!
Based on your voltage readings you do not have a 240 system, you have a 3 phase, 4 wire 208/120 system where phase to phase voltage (A-B, B-C, C-A) are each 208V, and a phase to Gnd voltage (A-G, B-G, C-G) are 120v each.
You can still use the 240V heaters but at 208 you will not get the same heat output (2270 vs 2510 if I did the math right). There are few ways you can hook them up depending on the breakers you have available:
- Feed each heater with a 2 pole breaker (4 breakers needed)
- Feed 2 heaters in parallel with a 2 pole breaker (2 breakers needed)
- Feed all 4 heaters in parallel with a 2 pole breaker (1 breaker needed)
- Feed 3 heaters in a delta configuration with a 3 pole breaker and 1 heater with a 2 pole breaker (keeps phase current balanced on breaker)
You can still use the 240V heaters but at 208 you will not get the same
heat output (2270 vs 2510 if I did the math right).
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2510 * (208^2/240^2) = 1885W, if what you are surmising is true.
Sounds like you have 240, 3Ph, with the neutral in the middle of one of the sides of the triangle (thus if you measure from one of the vertices on the side that's grounded, you get 120; if you measure from the opposite vertex you get 208). It's called "bitch leg" or "stinger leg" 240 and is an old configuration, not too common anymore.
It's still 240V, 3Ph, so if your heaters are single phase, any two phases will still provide 240V, 1Ph, and all three would provide 240V, 3Ph. The location of the neutral point is irrelevant for your application.
If the other poster is correct and you actually have a 208/120 Y panel, then you still use two or three hots for a single or three phase heater, but you'll get 75% of the wattage. Will still work (assuming 75% can get the job done), but will run a little cooler and may last a little longer because of the lower watt density.
