DOL Contactor - 2 separate isolated 24V coil inputs?

Hi all, wondering if anyone has run into a similar situation, I have a bore pump being driven by a DOL contactor with a 24VAC coil. I wish to be able to activate the coil via 2 separate 24VAC inputs that can't combine or back feed each other, one is the output from a standard irrigation controller, the other will be via a DIM mount 240VAC->24VAC transformer driving a manual push button circuit on front of panel. Has anyone done something similar whereby the two inputs are essentially kept separate and unable to both active together? a four gang rotary switch would obviously be able to handle the logical switching but wondering what others had done.

Cheers,
Richard
 
If you want only one or the other 24VAC source to be able to control the coil at a time, a selector switch is probably the simplest. Since one of your controls is a (local?) pushbutton, you could add a Hand-Off-Auto switch (3-position selector switch). In "Hand"mode, the pushbutton controls the pump. In "Off" mode, the pump is always off. In "Auto", the irrigation control controls the pump.

If you want the pump to turn on if either the button or the irrigation control (or both at the same time) calls for it to run, use interposing relays. I threw this sketch together a while ago for someone who asked a similar question, only it was independent external 24VDC sources. Your application would be very similar.

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