For years I have always up sized the breaker by at least 125% of the load on an Insta-Hot (sometimes known as a Tankless Water Heater). Now I find out that since it is considered a non-continuous load, I can size the breaker according to the load, at least according to one supplier and a company tech rep I talked to.
This would have made things much easier if I had known this, but am glad I know now.
Doesn't it seem to be pushing it too close to have the breaker right at the amp load? What about nuisance tripping in case of a weaker or eventually worn breaker?
Factor in things like voltage drop or perhaps the device slightly raising it's ampacity over time due to wear or tear, it seems like a potential for at least some minor problems.
Another question I have is whether a disconnect is required under the sink with the Insta-Hot. A well respected (and feared by some) inspector told me that if there was not a requirement on the blueprint for a disconnect, it doesn't need one according to code. I definitely always label the breaker in the panel and write on the insta hot what circuit and panel it is.