Hot water heater wiring the correct way?


Old 01-17-16, 03:23 PM
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Hot water heater wiring the correct way?

Hi All

I discovered a little while back the prev owner wired the hot water heater on a 15 amp with 14/2 wire. Its a 40 gallon tank which is what I'm going to replace it with when I do the rewire. They also didn't run the 14/2 to a box then on BX to the tank. They just cut a piece of BX jacket and slid the 14/2 wire into it. The wall end is sharp with no box just hanging. Correct me if I'm wrong but jacketed wire should not be insulated right?

Anyhow it's all kinds of wrong. I've got the 20 amp breaker and 12/2 wire and breaker panel end no probs.

What I'm thinking will make this right an up to code is. Run the 12/2 to a box beside the tank on the wall. Knock out a slug and run BX or liquid tight (can I use liquid tight for this? I've got it already) and buy 3 single 12 awg conductors black red and green to run from the wall box to the tank. Does it matter if these loose conductors are solid or stranded copper?

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Old 01-17-16, 03:27 PM
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Not sure of the requirements of the water heater (and Canadian code) but normally they are wired with a double 30 amp breaker with 10 gauge wiring, whether in conduit, flex or other where exposed.
Old 01-17-16, 03:36 PM
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Water Heater

Gas or electric water heater???
Old 01-17-16, 03:38 PM
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Hi Larry

Its a 40 gallon electric. 3000 watts 240 volt = 12.5 amp draw dedicated so 20 amp 12/2 will do. I think if went to a 60 gallon then yes the 30 amp would be required.
Old 01-17-16, 04:15 PM
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Your idea is a good one. You can use Greenfield (like BX) or liguid-tite. Both would be ok.
The wiring can be solid or stranded.

That must be a very slow recovery tank with only a 3K element. Most are 4.5K.
Old 01-17-16, 04:47 PM
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Even if your water heater is only 3000W, I'd still run 10-2 so you can upgrade your water heater later.
Most water heaters are now 4500W (Even in 40Gallon) and you will have to run new wire again when you replace your water heater with it.

Personally, I'd just leave at current 14-2 until you need to replace water heater.
12.5A is 83%. Maximum continuous load on the breaker should be 80%. For 15A breaker it is 12A. I wouldn't worry to much about 500mA..
Old 01-17-16, 05:32 PM
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The water heater wiring needs to be sized for 125% of the load.
Old 01-17-16, 05:46 PM
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I agree with everything that lambition wrote.

Something else to consider is IF the water heater is not in a direct line-of-sight AND fifty feet or less from the circuit breaker then either a circuit breaker lockout device needs to be used OR a local disconnect switch at the water heater itself.
Old 01-19-16, 04:18 PM
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Thanks for the advice everyone. I think I'm going to stick with a new 3000watt heater and the 12/2 on 20 amp run.

Right now my kids are young and hot water usage is not crazy. I plan to eventually switch to either an on demand gas system or solar but they are expensive and as long as this one provides enough hot water I'm good with that.
Old 01-20-16, 11:36 AM
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I personally like getting an Air Conditioner whip. It's liquitight conduit with the correct fittings and wires pre-run in the tube. Connect it to a 4x4" box and you're good to go.

As Furd mentioned, add a DPST switch as a shutoff and you're totally code-compliant. (You can use an air conditioner disconnect too if desired).
Old 01-20-16, 11:53 AM
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And if you use the air conditioner disconnect you don't need the 4x4 box. Use the pull out kind of disconnect it might even be a bit cheaper the a switch and a 4x4 box.

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