Old home - hot water heater simple wiring


Old 10-08-04, 03:40 PM
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Old home - hot water heater simple wiring

Please forgive the stupidity here..

Our boiler used to feed the fixtures for hot water heat (arrggh!) - big ole farm house. I am installing an electric water heater. The guy gave me 10/3 wiring. I want to make sure I don't get this screwed up.

The heater has two wires of course: red and black.
The 10/3 has of course black/white/red

Which wires are to be connected to the heater? and at the breaker?

Your help is appreciated because I can't get a clear answer from even the retailer that I bought it from, nor will an electrician give me the time of day.
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Old 10-08-04, 04:00 PM
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Join Date: May 2000
Location: Eugene, Oregon
Posts: 5,841
For 220v heater it does not matter, both lines carry the same current, 2 110v lines, can connect to either wire at the heater.

Panel not sure, I'll copy this to the electrical forum, so check there also.
Old 10-08-04, 04:29 PM
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
An electric water heater needs only pure 240 volts. It does not need a neutral.

Use the red and black wires in the 10-3 cable for hot. At the panel end they should be connected to both terminals on a 240 volt 30 amp breaker. The white wire can be disconnected and capped off at the panel. If it is already wired to the neutral bar then leave it. At the water heater end connect the red and black wires from the cable to the red and black water heater wires. Leave the white wire disconnected, but capped off.

At both ends connect the bare ground wire correctly.
Old 10-08-04, 04:37 PM
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I truly appreciate the quick response Rac, and the copy-over Plumber. I honestly figured that to be the case but wanted to make sure. Again, thank you....

Old 10-08-04, 04:50 PM
Join Date: Sep 2002
Location: welland ontario
Posts: 5,599
You could havve actually wired it with 10/2 and used the white inplace of the red.

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