SSR Wiring w/ On-Off-On Switches

I’m looking for some help creating a schematic for a Photon controlling a relay with an on-off-on switch.

I would like to have a 3 way switch that either connects a relay directly to a 12 volt power supply or to a Photon pin that I can control remotely.

Here’s the parts that I expect to use (see attached image)

  • Photon sitting in a Particle Relay Shield
  • 12 Volt PSU
  • Fotek 40 amp SSR 3-32 VDC input
  • Electric Panel Switch, 2 inputs, 2 outputs

I’ve attached a diagram of my assumptions. Can someone confirm this approach or point out any obvious errors, or suggestions on improving the circuit?


Let me ping someone that might be able to help, @rickkas7 or @ParticleD are you able to assist?

What you are describing would be accomplished with a Hand-Off-Auto (HOA) Switch.
Hand = Manual Mode, Local Control
Off = Off
Auto = Photon Mode, Remote Control

You can use a Relay on the Board to switch 12V On/Off to the SSR while in Auto Mode.

Google HOA Wiring and you will find lots of diagrams.
Here’s an example..

The Goal is for anyone to be able to follow the wiring in the Field. Driving the SSR via a Digital Pin directly is not as obvious as using the Relay in the Automatic Circuit.

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Thanks @Rftop, that’s it.

Is it “better” to use a relay to drive an SSR in this situation or is the digital pin sufficient? Assuming that is, that I choose not to use a relay board.

If you decide not to use the relay board, you can still add a cheap 1 channel relay “in-line” in the “Automatic” Circuit for the Digital Pin to control.
That way, you are using 12V to operate the SSR on both Manual and Automatic modes.

I’m not an electrician or a EE. But in my mind, the Switching for the Auto Mode should happen “downstream” of the HOA selector. I.E. the HOA will send 12V to either the Manual circuit, or the Auto circuit. Your photon controls a relay just before the SSR to switch that 12V on/off, when the HOA is in Auto Mode.