Do illuminated switches pass current to the load side when off?

[elsutjr]

I installed an illuminated switch (switch is lit when circuit is off) for my porch light. I noticed that even when off, my LED porch lite is dimmly lit. I measured the voltage at the socket and it was 25VAC. Is this expected or did I install a faulty switch?

 

[Avo Mk8]

Yes to the title of your post!
Probably not a faulty switch, but a 'feature'!

 

[mainline]

I would expect the porch light to be off when the switch is off.

 

[Avo Mk8]

A more comprehensive reply to the OP would be that if the illuminated switch were double pole, switching both live and neutral, then the illuminating neon/led would be across the supply, and not powered through the load.
Where the switch is single pole, traditional for a light switch, and merely interrupts the live supply, the illumination is usually wired across the switch terminals, and draws current through the load when the switch is off.

The product below warns "requires a filament bulb to operate correctly"
It might be that a neon version would not draw as much current, and not illuminate an led light fitting as per the OP's situation.

 

[mainline]

A more comprehensive reply to the OP would be that if the illuminated switch were double pole, switching both live and neutral, then the illuminating neon/led would be across the supply, and not powered through the load.
Where the switch is single pole, traditional for a light switch, and merely interrupts the live supply, the illumination is usually wired across the switch terminals, and draws current through the load when the switch is off.

Like you did in post #2

If it were d/p and across the supply, it would be on all the time btw.

 

[elsutjr]

Like you did in post #2

If it were d/p and across the supply, it would be on all the time btw.

Like you did in post #2

If it were d/p and across the supply, it would be on all the time btw.

This is just a simple signle pole switch. When using a filament bulb the light is off, but the LED-type bulb is dim. Since posting this question I took a second switch (I bought two) and just carefully wired it up to AC and sure enough, when it is "OFF" I still see about 25VAC. That really surprises me... assuming that means its supposed to be like that (figuring I didn't buy 2 faulty switches), then what if I had a motor or something other than a simple light bulb on that circuit...

 

[Avo Mk8]

I'm assuming your single pole switch has the internal illumination wired across the switch terminals. When the switch is 'off' the internal illumination bulb is in series with your led porch light. Their respective impedances dictate what voltage exists across the switch compared to that across the led porch light.

When you put a filament bulb in the porch, which is low impedance when it's 'cold', effectively all the voltage is across the open illuminated switch, so the switch illumination bulb will be at its brightest. This is how it is assumed that some illuminated switches will be used.

When you put an LED bulb in the porch light, obviously that will draw a lot less current than the filament bulb. The behaviour of the LED bulb in series with the source of illumination in the switch will depend a lot on the wattage and characteristics of the bulb, and also the type of illumination source in the switch.
I think it's fortunate that your LED porch light doesn't flash rather than glow.

I notice that the blurb on Amazon UK for the switch you gave a link to says "This switch is compatible with incandescent loads only and is not recommended for use with LED or CFL lamps."

One possible solution might be to fit a snubber (series capacitor and resistor combo) across your porch light connections.

RC Snubber | Shelly Store UK | Smart Home Automation

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shellystore.co.uk

(sorry - link to a UK site)

Re your last query, if you put a motor or similar (which I guess you're not actually going to do!) in place of the porch bulb, then the small current that powers the switch illumination would flow through the motor, but likely wouldn't actually move it!
Similar to you putting the filament bulb in!