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#180169 08/15/08 04:52 PM
Joined: Dec 2002
Posts: 32
W
wiking Offline OP
Junior Member
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.

2017 / 2014 NEC & Related Books and Study Guides
Joined: Jan 2001
Posts: 1,044
Tom Offline
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Your supplier & tech rep are correct about circuit sizing. See 422.10

The circuit breaker can sevre as the disconnecting means but will probably need a provision for attaching a padlock and the provision must remain in place with or without the padlock. 422.31(B)


Few things are harder to put up with than the annoyance of a good example.
Tom #180196 08/16/08 12:35 PM
Joined: Jul 2004
Posts: 9,663
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G
Member
Around here they will usually want the local disconnect. Our AHJs do not think much of residential LOTO capabilities. Up to 20a this is usually cord and plug, 25a and up is going to be a pullout or switching device.


Greg Fretwell

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