Originally Posted by audger
FWIW- i have a 2kw 120v element in my HERMS tank, too. it pulls just over 15 amps in actuality. its good to have some head room built in, but if you are using the ballpark of 20+amps, you may be way over-provisioning.
This would be because you don't actually have 120V available. You only get 2000W if you run on 120V, and that will pull 16.6A.
If you actually measure 110V in your outlets, then your 2kW element is functioning only as a 1680W element and pulling 15.3A.
Everyone gets a little variation in their voltage measured at the outlet. I measure almost 125V on my outlets, and I know people who measure 110V. That's a significant difference when it comes to power.
edit: at my house, a "2000W/120V" element would actually be a "2150W/125V" element and would pull over 17A. that's almost a 500W difference between 125V and 110V.