Is This How I Wire A 240v Timer? - Electrical - DIY Chatroom Home Improvement Forum

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Old 04-23-2009, 04:46 PM   #1
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Is this how I wire a 240v timer?

Yozit, I know you mentioned I'd save a few cents getting a timer but 8.8kW each time a particular situation arose at 23 cents/kw that's a couple bucks each time the situation happens, occuring around 50 times a year I think the $28 timer worth it (but I also don't expect to save $100/year with it either).

The timer I'm looking at (Intermatic WH21) install instructions are at

Is my drawing of how to wire it correct (I used Red but the true wire is white)? I'm used to these timers having their motor run on 120v and require a white neutral to the bus bar, and usually only one leg goes to the timer and the other to the load. The instructions give me the impression the motor runs on 240v and it wants both lines even though only one is switched. Anyway, does my wiring diagram match the install instructions?

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Last edited by Piedmont; 04-23-2009 at 05:01 PM.
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Old 04-23-2009, 05:54 PM   #2
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I wouldn't use that timer. It appears that it doesn't disconnect both legs. It may be legal but if you get a double pole timer it can serve as your disconnect also by turning off both legs.

Intermatic T 104 is about $35 I think. When you pull the guts out you can turn it over and see exactly how it works.


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Old 04-23-2009, 07:45 PM   #3
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That's the kind of timeclock I'd recommend as well. Not very expensive, and pretty much bullet-proof.

They usually have 40 amp contacts, just make sure to get one with a 208-240 volt clock motor.

I've had better luck with the mechanical ones than the electronic ones.

The mechanism of a brand new one will usually fit in a box thats 40 years old. They had a winner, and stuck with it.

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Old 04-23-2009, 09:16 PM   #4
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The T104 and the WH40 look like they have the same design and specs with DPST the WH25 however only has a SPST. So I would go with the T104 or the WH40
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