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I have a problem that I believe there is a solution to but I'm lacking in the knowledge on how to do so.

There two switches in a building. Both are single pole single throw switches and cannot be changed or replaced.

I need to make these operate like a standard 2 way switch you'd find at opposite ends of a hallway to control a single light.

There are cables for live, neutral and ground, with two travelling wires between both switches.

I've seen somewhat similar questions answered by suggesting the addition of a flip flop switch or a relay, but I'm not confident on how they work so don't want to risk a short circuit.

Would anyone here be able to advise on this? I would gratefully appreciate any input.

denismoc
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1 Answers1

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It's not impossible, but might not be a good idea.

schematic

Figure 1. Original, current and future(?) wiring.

Option (c) converts the lines to DC. SW4 will pass positive half-cycles and SW5, negative half-cycles. RLY1 will energise on positive and RLY2 on negative. The relay contacts perform standard 2-way lighting function.

Your technical problem now becomes finding a device that will switch on with half-wave DC current and not chatter violently. Opto-isolators are another option, would be silent and integrate easily with a "smart relay" to do the switching logic.

Your compliance problem is whether or not this is legal and meets local electrical standards.

Transistor
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