WH40 Timer - 240v and 120v circuit wiring

[Bill Berry]

Here's what I currently have: Whirlpool 20 gallon (1500 watt element) 120 volt water heater. My old tank was a 23 year old 3500 watt 240 volt water heater. Yes, I'm aware I can change out the WG1573 clock motor in favor of a WG1570. The wiring in the wall is 10-2.

This is what I want to do: With the existing 10-2 in the wall, I want to keep that wiring to the WH40 timer intact thus I can supply 240v power to the WG1573 clock motor. I want to run a solo (white) neutral wire from my service panel's neutral bus to the WH40's neutral tab "A". Run 10-2 from the timer - black on L2, white (neutral) on tab "A", ground to ground. Then run this to the water heater which is 120 volts. I will not be adding anything else to this setup.

And this is what I need to know: Is this acceptable? Or do I need to run 10-3 and do the exact same thing? Running a solo (neutral wire) from the neutral bus in essence allows the 10-2 wiring to become 10-3. I've tested everything and everything is as it should be. I just need to know whether there's code to back this installation up or as I just said, do I need to run 10-3 to have both a 240v and 120v connections coming out the WH40 timer from the service panel and to the water heater; thank you!

 

[Jadnashua]

Code doesn't allow you to run that separate neutral. IT all needs to be within one cable, or separate wires in a conduit, and no, the existing wires in the cable are probably not rated to be run inside of conduit.

 

[Sponsor]

 

[Bill Berry]

Code doesn't allow you to run that separate neutral. IT all needs to be within one cable, or separate wires in a conduit, and no, the existing wires in the cable are probably not rated to be run inside of conduit.[/

Thank you, that's what I needed to know; my service panel and water heater are less than four feet apart; so it doesn't really matter whether I run it through conduit in the wall or just go on ahead and replace the 10-2 with 10-3; correct?

 

[hj]

Change the element and thermostat in the heater to 240v

 

[Jadnashua]

You're building a non-standard circuit and the UL safety rating on the device may become void. You will need to retain your two-pole breaker, but as HJ said, it would be probably easier to just swap the element for a 240vac one, or buy a new timer. Keep in mind, a 1500W (for example) element at 120v requires 1500/120=12.5A, but a 1500W element at 240v only needs 6.25A. What are the switching contacts on your timer rated for?

With a quality electric WH, unless your use of hot water is very erratic, the standby losses aren't very much. I suppose if you have off-peak rates, a timer might be worthwhile, but if you don't and the utility company doesn't provide a timer or switch, trying to save money by turning it off won't really buy you a whole lot. Some of the better tanks only have a 1/4-degree/hour standby loss, so over a 24-hour period, it would only drop 6-degrees...hardly noticeable.

 

[WorthFlorida]

Are you replacing the old 40 gallon 240v unit with 20 gallon 120v unit with one heating element? If you are you may find that you'll be runnin out of hot water. Unless you're a one or two person home and short pipe runs and know the limits, you'll be OK.

However, the water heater cannot be changed to a 240v @ 4500 watts unit because the upper thermostat is not made for 240v connection. If you do replace the heating element it will put out no more than 2250 watts at 120v which you can do. The upper thermostat may look similar but the 120v unit will have less screw connections.