On Saturday, December 15, 2018 at 11:24:25 AM UTC-5, wrote:
On Sat, 15 Dec 2018 04:44:16 GMT, albert
m wrote:

replying to Burhans, albert wrote:
I'm also adding an AC 120V 20 amp outlet next to the water heater. After
looking around could not find a 20/25 amp dual breaker. The local ACE hardware
carried no 25 amp breakers. Home Depot had a 25 amp breaker but wasn't the
right type to fit my load center.

A 30 amp breaker might not trip or trip in time when connected to a 2000 watt
heating element. So I for now I'm going to use a 20 amp breaker (20/20, 20 amp
for the water heater and 20 amp of a 20 amp AC outlet)

If wanting a dual breaker I haven't been able to find a 20/25 amp dual breaker
anywhere. Perhaps a store such as Platt electric might have such a breaker?

I'm using 10 gauge wire. Purchased 20 feet 4 x 10 gauge. Hot, hot, neutral
and ground. $1.96 per foot to be installed into 1/2" PVC conduit as the main
part of the run is outdoors. Metal Clad can be used outdoor only if protected.
PVC can be used indoors, outdoors and underground.

Another option would be to swap out the 2000 watt heating element for on
that's under 2000 watt such as a ~1700 or ~1800, etc. watt element. Then one
can use a 20 amp breaker with 12 gauge wire and be up to code.

The only code issue is that the wire and the equipment is adequately
protected. As long as you are using 10 gauge wire you would be OK with
a 20, 25 or 30a breaker.
The continuous load language and the word "ampacity" itself refers to
the wire, not the breaker. If your voltage is nominal or lower (120 or
less) A 20 should work fine on a 2000 w element. That is 16.66 amps
and close enough for government work for an 80% breaker

Especially considering that you'd have to either have some pathological
usage of that water heater or leave the hot water faucet running for
3 hours to get to a continuous load to begin with.