Weird science

LED panel (when switched on)

I have LED lighting panels in my bedroom, two of them. Nothing complicated.

They each have a power supply behind them in the ceiling, and connect to the power with just live and neutral (no earth).

The live goes via a switch, obviously. It's a Shelly, so a clean relay contact.

So, when they are off, they should be off. Simple. They only have the neutral connected at that point.

The weird bit

However, during the night, I can see that they are not quite off. They have a faint glow some of the time. It can only be seen in the pitch black of night, and when your eyes have adapted to the dark. So if I wake up in the night I can see it.

At first I did wonder if I was imagining it, it was so faint, but no, I have seen them glow turn on and off, not fading in/out but sudden on/off. So very real. They are not glowing all the time, and not at the same time necessarily - sometimes one or the other. But most of the time as far a I can see, i.e. if I wake up in the night they are glowing. And frankly they are annoying me.

But with only neutral connected I don't see how this can happen at all!

The weirder bit

This only started happening the day my battery was installed. I have had these over 18 months and never seen then glow before, but they do now, every night I see them.

How can my battery install have triggered this?

The even weirder bit

The point the battery stopped powering the house

As I say, I now see this every night, well, except for last night. Last night I turned off the hot tub and allowed the house to run on battery all night for the first time. To be fair, I kept checking the battery charge in the night. Sad, I know. But yes, the battery lasted not only until sunrise, but until enough solar to run things and start charging it again. That means I have not used any power from the grid for over 24 hours, and in fact exported 9½kWh, even using the hot tub in the day yesterday. Amazing.

But, guess what, the lights did not glow last night, not once did I catch them doing so.

So they only glow, once the battery was installed, but only when it is in standby, not powering the house.

I repeat, there is no earth on these lights. And the extra earth rod for the battery install was done 6 months ago anyway. So all that changed when the battery was installed was, err, the battery and gateway box.

I may play with switching the neutral as well, but wow, why would I need to do that.

Explanations welcome!

Update

Usually the switch for a light like this would be L/N to the ceiling, the L going all the way down to a light switch, and all the way back, in the same wire/sleeve, to the ceiling, and then in to the light with N. This long wire acts as a capacitor allowing small amounts of AC current to flow.

But sorry. My lights are L/N to a shelly, L via the relay in shelly, and the L(switched)/N on to the light. No cable to act as a capacitor. Nice try twitter.

Further: We are planning to take up floor boards tomorrow (Friday) to confirm wiring is as I remember it, and try some things - I'll post more details here when I know. Thank you all for the ideas on this.

Final answer

Firstly, there is no switch lead, so capacitive pick up L to Switched-L was not the cause.

One person sort of got it right, a lively neutral. But not quite what you may think. In fact it was L/N tails to CU reverse, so all neutrals were very live and unprotected. The cable to the light therefor had a live (on neutral wire), and an earth (not used at light, but obviously connected to earth), and next to the earth was the neutral (on the switched live wire), which capacitively picked up from earth and power the lights.

Yes, there was a big flash and a bang in discovering this. No, I am not going to point fingers (was not me, obviously).