Switch question

Old 06-02-04, 07:26 PM
Don W's Avatar
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Switch question

Can I use a 3-way switch to switch 2 supplies of power to one source safely?
I posted this question earlier and did not get a response-- might have been too wordy. I want to power a pool pump with an output of a timer, and straight line voltage. Both supplies are 110v and are essentially the same supply, one from the timer and the other before the timer. If a 3-way is not practical or safe, could someone come up with a solution? Thanks.
Old 06-02-04, 08:09 PM
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If installed properly, you can use a 'three way' switch as you describe. If you think about it, this is exactly how the second three way switch in a three way switch circuit functions.

I would be careful of the following:

1) make sure that the two 'feeds' into the three way switch can share the same neutral--most simply by making sure that they both come from the same breaker.

2) while not always required by code, it is a good idea to make sure that current flowing in a conductor in a cable is balanced by current flowing in the opposite direction in another conductor. I strongly recommend that you place your 'bypass' switch in the same junction box as your timer, or connect the bypass switch by a three conductor cable back to the timer junction box.

3) Another way to do this is to connect a standard single pole switch 'across' the timer, bypassing the timer when the switch is 'on'. The problem with this arrangement is that (I have heard, but do not know with certainty) some timers can be damaged by placing 120V on the output (load) side of the timer when the timer is supposed to be off.


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