Re: New Water Heater Wiring?? Couple quickies..
You will need to provide the wire going to the water heater; for a 30A circuit (common for water heaters) you will need 10/2 w/ground Romex. (10/3 is not necessary.) If the sub-panel was installed properly, there will be a neutral bus and a separate grounding bus. Do not connect the ground wire to the neutral bus. If you're not sure which is which, the neutral bus should have a large white wire leading to it, and the grounding bus should have a bare or green wire.
It doesn't really matter if the wire from the ceiling to the switch is in PVC or metal conduit, but if it's metal conduit it will need to connect to a metal box, and the ground wire in the 10/2+Ground cable will need to be connected to the box itself. Make sure the conduit is fastened to the wall. If using metal conduit, install a box fitting at the top with a plastic bushing screwed on the threads, to prevent the sharp edge of the conduit from piercing the insulation. Be sure to use a cutout switch rated for 30A.
(In the switch box, use a large wire nut to connect the incoming ground, a lead to the box, a lead to the switch if it has a ground screw, and the wire to the water heater. All ground wires should be 10 gauge.)
As for the wire to the water heater, use a piece of flexible conduit -- again, either metal or plastic is OK, just be sure to use the proper connectors -- from the switch box to the water heater. You'll probably want to have about 3 feet of flex conduit, and the wires should extend another foot (if too long, they can be shortened when installed).
One more thing: since this is a 240V only circuit, if you use 10/2 romex, be sure to color the white wire at both ends either by wrapping it with black tape or coloring it with a permanent marker. This indicates that it's not a neutral wire, and it's required by code to mark it.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.