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#202677 - 08/21/11 11:59 AM Tankless Hotwater heater
dougwells Offline


Registered: 05/03/03
Posts: 1226
Loc: kamloops BC Canada
I have an inquiry about installing a circuit for this Item.
Will this need a sub panel and am a bit rusty about the feeder size for the a sub panel.
Has anyone installed on of these thanks.
This will be a renovation

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#202678 - 08/21/11 07:54 PM Re: Tankless Hotwater heater [Re: dougwells]
Tesla Offline

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
"3 x 50 AMP breakers (depends on local codes)"

Each breaker at 240 VAC

"Minimum 3 x #8 AWG Copper (depends on local codes)"

So you'll need at least #8 -- but more likely #6 conductors.

(I'm assuming that you'll be dealing with a 60 degree panel board and or are using Romex. Otherwise, you'd be able to use #8.)


I've never installed such a beast.

Instead I've installed insta-hots 30A @ 208 or 277...

You'll have to deal with line-of-sight disconnecting means -- which normally is addressed by a sub-panel rated 150 Amps @240VAC.

You can pipe and wire the feeder -- or use MC -- they make it big, BTW.

MC is available all the way up to 705 kCMIL. (!)

#202679 - 08/21/11 08:54 PM Re: Tankless Hotwater heater [Re: dougwells]
jay8 Offline

Registered: 07/28/05
Posts: 183
Loc: Vancouver, BC
I am a little suprised at the electrical layout. The manufacturer is suggesting three breakers to a single control panel. How do you effectively isolate the unit for service, normally there is a single point of isolation on the control panel such as a service switch on the front of it.

Also, from the drawing (page 13) it looks like the exposed L1/L2 terminals are right next to the inlet and outlets ports for the water piping. The drawings show wires running right past the mechanical piping within the control panel. Unusual to say the least that there seems to be no barrier between the sections.


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