Was recently looking for a solution for automating an under cabinet light that only has hot and load in the switch box.
Don’t really have an option to do anything at the light.
Challenge I have is no ground or neutral in the box to power the relay.
I was looking at the Zooz xs relay. Can power 240 3A. Can be connected to a switch so I can get control at the switch or remotely.
And it looks like it can be powered with low voltage.
If I powered this with a 9v battery ….i wonder how long it would last?
Alternatively. The light switch is directly next to an outlet. I could plug in a 9v wall plug and win it behind the switch plate into the light switch.
But. Battery would be cleaner …if it would last !
Food for thought.
Mac
You need a "no neutral" relay. Something like this product from Sonoff would work:
That’s awesome. And why I trust the community over AI 
I was thinking something would require a ground at least so there would be a return path to power the relay circuit.
Will order and give it a try. Worst case. 15 bucks if it doesn’t work !
Thanks.
Ordered 2. Should be b delivered before the weekend
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I’m not familiar with 240v circuits in Asia but unless they do things very differently, ground is not “a return path to power the relay.”
That’s the definition of the neutral wire.
The ground wire is there as a safety mechanism if a fault condition exists, to allow current to flow back to the circuit breaker and shut down the circuit (rather than alternative paths for current flow, like a person that touches the switch).
Apologies in advance if I’ve misunderstood how things work where you live, though.
You didn’t mis read it. I mis wrote it
I’m more used to North America where there is a 120v and a neutral. I’m assuming here the hot is 240 and the other wire is neutral.
In this case. There is only the single hot going to the switch and the return hot going back to the light. Was wondering how a relay works when there is no neutral but a quick ai search tells me that the relay leaks some current back to the light. Not enough to power the light but enough current to create a small potential across a resistor that will power the relay circuit.
Either way. I ordered a couple.
Cheers. Mac.
Best not to assume anything when working with 240v yourself. Good luck (and be safe).
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Just be aware that due to the way these devices operate, there will be a few milliamps of current passing through the device, even when it is turned off.
This usually isn't an issue for devices that require a lot of current to operate (like incandescent bulbs), but devices that require very little current (like LED lights) may glow dimly, or flicker, when the relay is off.
So if your under cabinet lighting is LED, you may experience this issue. There are some methods to reduce the problem, should you notice it.
Noted. I’m prepared to change the fixture if is comes to that. It’s a rental but so far they’ve been good with me paying for upgrades I’ll leave when my lease is over.
Noted . I’m fairly comfortable with electrical. Been many years but I did complete a 3 year electrical engineering technology program back in the 90s. Always turn the breaker off and check with a meter ! Back then. Wasn’t much for home automation and my program was designed for high power applications. Wayy more comfortable with high voltage than I am
With writing files in HE
NEC has relaxed some rules on ground for electronic switches. They can use the ground wire for a reference as long as current draw is very low. I’m not sure the amount but I think it is 100s of micro Amps range. These switches take advantage of that ruling.
That said generally when it’s a dead end switch leg there is more options (hot, neutral, switch leg) in the fixture box where you could bury a module. ZEN51