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Discussion Starter · #1 ·
Is there a device that will automatically switch between two AC inputs to send power to one AC output? (quick delay during switching is ok)

Here is an example of that I am looking for...

A device with INPUT A from one source and INPUT B from another (maybe different sides of the circuit braker panel possibly opposite phases.

If inputs A and B both have power, output C would only get power from input A.

If input A loses power, output C would switch over to power from input B.

I would never want any power to connect between A and B because that could cause a short of feedback and that would be dangerous.



As an added note, if power does switch over to B, it doesn't have to return to A if both have power but should switch back to A if B loses power. Basically, get me power from A or B and I don't care how that switch happens as long as it is automatic. It is ok of there is a fraction of a second delay during the switch over as I am only trying to control lighting or devices that won't be damaged by a trivial power loss.
 

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A "Handy Husband"
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A DPDT relay with an AC coil connected to input A. Connect the common terminals to the output and connect the transfer contacts to the inputs.

Sent from my RCT6A03W13E using Tapatalk
 

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Discussion Starter · #5 ·
A DPDT relay with an AC coil connected to input A. Connect the common terminals to the output and connect the transfer contacts to the inputs.

That would be a cheaper simpler way to go it seems. Do you have a recommendation for the DPDT?

I am trying to control some lights if power is coming in from either of two sources. So 15A is just fine. The two sources may or may not be on the same phase thus the need to isolate them from each other.
 

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Why would your source have to be switched from A to B? The only way I can figure is if you're running lights with a genny, and when the genny runs out of gas you'd switch to line power, but I can't see why anyone would want to do that.
 

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Discussion Starter · #7 ·
Why would your source have to be switched from A to B? The only way I can figure is if you're running lights with a genny, and when the genny runs out of gas you'd switch to line power, but I can't see why anyone would want to do that.
Does why really matter?

I simply have a situation where I need lights to draw power from either of two power sources. Either source could be on or off for various reasons. It is possible both are on, one is on or both are off (and the lights go out at that point of course).

I just need to be sure that what ever I come up with that no power feeds back down the other channel so a relay situation sounds exactly like what I need. I am just not quite sure which relay would be my best choice. I don't work with AC and relays normally. I normally work with simply switches but I need automation in this case. It is a unique need for sure.
 

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Discussion Starter · #9 · (Edited)
It is a situation where we have some outdoor lights temporarily put up on a large plot of land so we can't run two full sets of lights. People may apply power from either of two discrete locations to the lights. The two locations will not be on the same source so the easiest thing is to run the power to the lights, put in a relay to switch between the sources then move on. If this were a permanent or long term solution I would use a three way switch so either side could control the lights but it is only going to be in place for a few weeks then it will be removed. But the idea may be useful in the future too so something that I can simply plug in the two sources and then the output would be very handy.

The sources are unknown at any given moment and shouldn't matter. I am betting they will likely be portable generators at either entry point thus the need for them to bring the generator, plug it in to this switching device and go.

Lets assume one group show up at one entry point and add their power. The lights come on and all is good. Another group arrive at the second entry point, radio the first and find out they are leaving soon. So they also connect their generator. When the first group leaves, they take their generator and the lights switch to the other to keep going.
 
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