Water Heaters - Two Hot Wires?

Hi,

I just replaced an electrical water heater. Our old heater had 4 wires: blue, yellow, black, and red. The black and red were twisted together, and the blue and yellow were each attached to a wire from our circuit box. Both wires from our circuit box were red.

I assumed one of our red wires was live and one was neutral, but when I tested, they both registered as 120 volts.

When I went to finish the install on our new heater, I found that it has 3 wires: black, red, and green (ground).

Can't quite figure out how to complete the install (the new heater was missing an owner's manual and I couldn't find one online).

So I guess I have 2 questions.

1. Does it sound right that we had 2 hot wires attached to our old heater?

2. How do we hook up our new heater (i.e. how do the 2 wires (not including the ground) relate to the old 4?)

Thanks.

OK, (I assume this is a 240 volt water heater, most are). On a 240 volt circuit you have two hot wires commonly refered to as L1 and L2. Each will measure 120 volts to ground. BUT will measure 240 volts to each other. The two hot wires are out of phase with each other. This is how it's supposed to be. Since a 240 volt water heater doesn't need or use a neutral, usually none is provided for that branch circuit.

So, if you are able to measure 240 volts from those two red wires from the breaker box, you are good to go. Just connect one red wire (from the breaker box) to the red wire of the water heater, and connect the other red wire (from the breaker box) to the black wire of the water heater. Connect your ground to the green.

Thanks!!! We have hot water again!

Good work. Thanks for letting us know how it went.

Here's another related question. The one thing still outstanding with this water heater is the metal cable surrounding the wires. I think it's called armor cable.

Our old water heater was much taller than the one I installed. The wires reach fine, but the metal cable surrounding them is too short so that now I have about 4 inches between where the metal cable ends and the wires continue into the water heater.

Thought I could just go to Home Depot and buy this metal cable but they only sell it in big coils; I only need a few inches.

Any suggestions or workarounds?

Thanks.