In article , "Bill C" wrote:

Can someone please tell me what AWG copper line is required to service a
68.5 amp 240vac tankless water heater? The manufacturer recommends an 80
amp breaker.

Anywhere between #6 and #2. Depends on the temperature ratings of the
conductors, and how they're installed (cable, conduit, etc).

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Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?