Is a tank type electric water heater a "continuous load"?
The real question is - Can a 4500W water heater be connected to an existing 20A, 240V (1ph) circuit? (18.75A?)
422.10 Branch-Circuit Rating. The branch-circuit rating for an appliance that is a continuous load, other than a motor-operated appliance, shall not be less than 125 percent of the marked rating, or not less than 100 percent of the marked rating if the branch-circuit device and its assembly are listed for continuous loading at 100 percent of its rating.
422.11 Overcurrent Protection. Appliances shall be protected against overcurrent in accordance with 422.11(A) through (G) and 422.10.
(E) Single Non–Motor-Operated Appliance. If the branch circuit supplies a single non–motor-operated appliance, the rating of overcurrent protection shall comply with the following:
(3) Not exceed 150 percent of the appliance rated current if the overcurrent protection rating is not marked and the appliance is rated over 13.3 amperes. Where 150 percent of the appliance rating does not correspond to a standard overcurrent device ampere rating, the next higher standard rating shall be permitted.
422.13 Storage-Type Water Heaters
A fixed storage-type water heater that has a capacity of 450 L
(120 gal) or less shall be considered a continuous load for the
purposes of sizing branch circuits.
Also consider that you are assuming 240V when in reality it may measure lower. If it is in reality 220V then your math no longer works.
422.13 Storage-Type Water Heaters
A fixed storage-type water heater that has a capacity of 450 L
(120 gal) or less shall be considered a continuous load for the
purposes of sizing branch circuits.
Also consider that you are assuming 240V when in reality it may measure lower. If it is in reality 220V then your math no longer works.
Is a tank type electric water heater a "continuous load"?
The real question is - Can a 4500W water heater be connected to an existing 20A, 240V (1ph) circuit? (18.75A?)
I would do 10 AWG conductor 25A OCPD
But the 20Amp OCPD may and will probably hold for short period of time. "short" will be interpreted differently.
The closer the current gets to 20A the faster OCPD will trip. I am sure you know that breakers are rated for 80% of their value. So the 20Amp will hold at 16Amps.
A 20A circuit breaker will hold at 20A indefinitely.
A 20A circuit breaker will hold at 20A indefinitely.
....where you get 220V?
You are referring to 100% rated circuit breaker?
Or you are saying if we have a 20Amp continuous load on 20Amp circuit breaker we don't worry about the 80%rule? because the breaker will hold for more than 3 hours?
A 20A breaker will carry 20A all day and all night. 80% is just a rule used in certain areas of the code.You are referring to 100% rated circuit breaker?
Or you are saying if we have a 20Amp continuous load on 20Amp circuit breaker we don't worry about the 80%rule? because the breaker will hold for more than 3 hours?
I see a lot of water heaters on 12 gauge-20 amp circuits. Mobile home water heaters often or usually have 3500 watt elements. When HO changes, he buys regular residential type with 4500 watt elements because they are cheaper.
The ones I see usually worked for a few years and then started tripping 20 amp breaker. Usually drawing 18 amps or less.
So why do I run across this average twice a year, 30 amp breaker hardly ever?
Any other heavy use circuits that are near by?
I don't know, never paid attention. How would this affect the situation? Heat? These are usually small panels, lately 200 amp, loaded with tandem breakers.