Electric instantaneous water heater
Electric instantaneous water heater means a water heater that uses electricity as the energy source, has a nameplate input rating of 12 kW or less, and contains no more than one gallon of water per 4,000 Btu per hour of input.
Source
10 CFR § 430.2
Scoping language
For purposes of this part, words shall be defined as provided for in section 321 of the Act and as follows -