I have a shop that has a 100 amp service underground from my home's service entrance. The service entrance in the shop has a single pole 30 amp going to a disconnect in a closet pre-wired for a water heater(220v wiring). The 220v wire in the disconnect has the 2 hots connected and the neutral free. Will this work on a 2 gal/min electric tankless heater?

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    The specifications on the water heater will state what size breaker is required. I assume this is a 240 V heater. I doubt that a tankless heater rated a 2 gal/min could be fully powered by one 30 A 2-pole breaker, but what do the specifications say? – Jim Stewart Sep 8 '19 at 22:52
  • What make and model of heater are you looking at, and why are you looking to go tankless here? – ThreePhaseEel Sep 8 '19 at 23:01
  • @coledog Did you ever hook your water heater up? – Ed Beal Dec 13 '19 at 15:05

The small tankless I have in my barn is very similar, 30 amp 2 Hot’s but the little array that actually heats the water is metals and has a place for the equipment ground. It would be a good idea for safety to connect the ground. Will the heater work without the ground? Most will. The heating element is 220v and all but 1 of these small units I have worked on were controlled by switches for flow no flow the switch could not close and heat the water. Don’t expect much out of this small unit it will get the water hot but how hot depends on the incoming water temp and the flow. For us it is just enough to heat the water to bathe horses before showing them.

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