Can I put a under counter refrigerator and tankless water heater(1800 watts) on a 20amp breaker?

What is the wire gauge? Will that be the only two appliances, no outlets or lights?

What is amperage of refrigerator? Eighteen hundred (1800) watts is 15 amps.

By code, no single cord and plug connected appliance can be more than 80% of a multiple outlet branch circuit. On a 20 amp circuit that shakes out to 16 amps.

Water heaters are considered to be continuous use so, (1800 / 120) * 1.25 = Amperage
1800/120 = 15 Amps. 15 * 1.25 = 18.75 Amps. So basically, the water heater is going to suck up 19 amps.

So, the answer is no. Place the water heater on it's own dedicated circuit. Use #12 AWG Copper for the conductors and protect the circuit with a 20 amp breaker.

Actually, an insta-hot water heater is fixed in place, so it cannot be more than 50% of the circuit.

Also, an insta-hot water heater is not considered a continuous load. That only applies to storage type water heaters.

Either way, no, this water heater cannot be on with another appliance or counter circuit.

Stan,

So the term "fixed-in-place" applies to the equipment, not the connection type as in hardwired? A fixed in place appliance can be either cord & plug connected or hardwired?

Actually, an insta-hot water heater is fixed in place, so it cannot be more than 50% of the circuit.


Stan, where is this in the book?

2011 - nec 210.23(a)(2)

Don,
Thanks! I was lost in different chapter...