there you go the answer you need to have.
I am not an electrician just passing along what I was told by an inspector maybe he was referring to a 20 amp breaker, I don't know but he did say 15AMP. My house has been inspected many years ago.
I always refer to the professionals as they know what they are doing. Kind of let Telecommunication stuff I know electricians don't know what i know about it they get the color code mixed up all the time. I have had to fix things that electricians have messed up many times. It's not their fault they have not learned this stuff they should be humbled and pass the telco stuff on to people that know what they are doing. I am straight up if i don't know I say i don't know, I do not pretend to know some thing that I have no knowledge about. That just gets people hurt I was working for a company that was riddled with people getting injured for no reason just stupidity and plain laziness. People doing jobs they know nothing about and people standing in the wrong place, things like that.

Notice I referred to the professionals.(I hope this helps, I would have a electrician take a look at it if you are not sure. They can do the calculations for you and give you a estimate on doing the work and then your house is covered.)

the other thing I am getting at do you know for sure that your tank is the only stuff on the circuit? Do you know where or not that line is not tied into some thing else.
Bill