I would like to use a 120 V 2K watt water heater element for anout an hour
from time to time as a boiler in my garage which also has a refrigerator in
it.The breakers in the house are 20 AMP.Will this circuit support this or
should I put the frig on another circuit?
Without pulling my calculator out, the heater draws about 17a. The max you
are supposed to put on a 20a line when used continuously is 80% or 16a. So
just the heater is an overload. You can probably get away with it (my 23a
water heater was hooked up for 30 years with #12 wire until I happened to
notice and correct it) but I wouldn't recommend it.
My old refrigerator drew 23a to start and 3a to run. If yours is
comparable, it will trip the breaker everytime it and the heater run at the
same time. Even my new fridge draws 13a to start and 2a to run, so that
will probably trip it also.
I would be inclined to run a new 30a line for the heater and use the
existing line for the fridge.
Can the heater be run on 240? Then it would only draw 9a and would only
need a 15a (or 20a) circuit which would probably be more useful in the
futuere. 240v is a good idea for anything that heats electrically.
120V, 20A = 2400 watts, x 80% = 1920Watts.
That's do-able, but not right. But
adding the fridge puts you over the top, so
you have to run a new line anyway.
Since this is a garage/workshop, it's not
possible to have too much power available,
so I'd spring for an extra $200 bucks,
and put in an 8-AWG 2-strand 240V cable
and a sub-panel, and a 50A 2-pole breaker.
Once you've gotten to needing to pull
wire, why screw around?
If the heater is a simple resistive element with the voltage connected
at the ends, plugging it into 240 will draw 33A and put out 8 kW. To
keep it at 2 kW at 240 V it would need to be rewired to use only 1/4 of
the element's length.
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