A family member's house currently has a gas WH that is quite old and I'd like to replace it before it fails. I'm trying to decide if I can go electric. The water heater is the only thing that currently runs on natural gas in the house, so it would be a simplification to get rid of it. Also the electric seems like less to worry about, no CO, flame etc, cheaper and easier to install, and from an environmental perspective the utility co is increasing renewable in the mix.
The dryer was on a three wire circuit which I upgraded to four wire for safety, that leaves an unused #10/3 from the panel that would be perfect for the water heater. The concern is whether the service supports it. The main is a 100A breaker, the panel is rated for 125A. I'm not sure what the wire size is on the service, presumably sufficient for 100A.
One of those on line load panel calculators came up with 129A. I did my own calculation and it looks like you'd have to have everything in the house on including all four stove elements and the oven before it would be a problem, but I suppose it's possible someone will be doing wash and cooking thanksgiving dinner and running two hair dryers. It seems like it would all be fine in practice but maybe this is just a full stop until I get an electrician in to evaluate the incoming service, or just go with another gas water heater. I did look at a hybrid water heater but it looks like they have backup resistance elements so no real help there. Cost is an issue as well. There are conventional electric water heaters with a little lower wattage (3800 instead of 4400 or 5500) so I figured on that.
small appliances 3000
total w/o range 19200
total w/range 26880
White 2012 SV delivered 10 Dec 2011 returned 25 Nov 2014 replaced with stopgap ICE Sentra
[35 months] [35K miles] [9 Bars]
2013 Volt replaced after 36 months/30k miles with ICE Rogue
2016 SV-adjacent May 2016 lost 4th bar March 2018