240v. / 1phase equip. compatible with 240v / 3 phase / 3 wire system? 2

[flaeng]

I have a spare 2 pole / 30amp circuit breaker in a 120/240 / 3 phase / 3 wire electric panel. Can I connect a 30amp / 240v. single phase water heater to the 3 phase panel?

 

[DanDel]

Usually, a 3-phase system will be 120/208V 4-wire(3 phases and a neutral), and a single phase system(center tapped) will be 120/240V 3-wire. The 3-phase 120/208V system will be 120V from each line to neutral, and 208V between each of the three lines.
There is such a thing as a 3-phase 240V system with one coil center tapped for 120V, but it is very rare and is certainly more than 3-wire.
Any 3-phase system with more than one voltage will have at least 4 wires, not three.
Why do you think that the system is '120/240 / 3 phase / 3 wire'?

 

[advidana]

yes

 

[alehman]

I am also confused about the number of wires. 120/240 3ph/4W (called a "hi-leg" system) was common 50 years ago, and is still found in some rural areas of the U.S. The center tap of one leg is grounded and used as a neutral.

If your load doesn't need a neutral and the system is 240 volts line-to-line, the answer is yes - either a 4W hi-leg system or 3W delta system will work.

If you do need a neutral, you would need the hi-leg system or install another transformer to derive the neutral.