Shelly 1L Installation

Neptune · Dec 5, 2021

Some background on my setup. I have a 4 gang switch in my hallway. Each switch has the switch cable coming down from the individual lights they control. The loop (and permanent live is at the light fitting). The switch I want to automate runs 4 external lights. 3 of these lights are 5 watt gu10 mans voltage and one is a low voltage strip light using a transformer.

1 of these lights has the wiring loop and the other three are daisy chained off this.

Can I use the Shelly 1L in the light switch? Do I need a bypass and where does this need to go?

Please let me know if you require additional information.

Thanks in advance.

littlespark · Dec 5, 2021

I don’t know a Shelly switch, but the big question is, does it require a neutral to operate?
It sounds as though there’s no neutral at the switch position.

Neptune · Dec 5, 2021

littlespark said:
I don’t know a Shelly switch, but the big question is, does it require a neutral to operate?
It sounds as though there’s no neutral at the switch position.

The Shelly 1L is designed to work without a neutral but I am unclear on the role of the bypass and how many are required in my situation

Avo Mk8 · Dec 6, 2021

Neptune said:
The Shelly 1L is designed to work without a neutral but I am unclear on the role of the bypass and how many are required in my situation

The spec says (to work without a bypass) the load the Shelly sees must be equivalent to at least a 20W resistive load. That doesn't mean there will be 20W dissipated - it will just provide a small 'leak' to power the module.

Assuming your three GU10's are LED's, I don't believe they will amount to that equivalent load. If the strip light has a real old fashioned inductive 'transformer', that might provide enough load. If it's an electronic "transformer", or an LED driver, then almost certainly not.
The bypass needs to go across the daisy chain, ie across the bulbs. One bypass for one Shelley.

You could experiment later to see if the setup continues to work without the bypass, but leaving it out might mean that a bulb failure, or changing bulbs for a different type, or a problem with the strip light, may stop it working. I'd leave the bypass in place.

Neptune · Dec 6, 2021

Avo Mk8 said:
The spec says (to work without a bypass) the load the Shelly sees must be equivalent to at least a 20W resistive load. That doesn't mean there will be 20W dissipated - it will just provide a small 'leak' to power the module.

Assuming your three GU10's are LED's, I don't believe they will amount to that equivalent load. If the strip light has a real old fashioned inductive 'transformer', that might provide enough load. If it's an electronic "transformer", or an LED driver, then almost certainly not.
The bypass needs to go across the daisy chain, ie across the bulbs. One bypass for one Shelley.

You could experiment later to see if the setup continues to work without the bypass, but leaving it out might mean that a bulb failure, or changing bulbs for a different type, or a problem with the strip light, may stop it working. I'd leave the bypass in place.

Thanks. So 1 bypass and not 4?

Avo Mk8 · Dec 6, 2021

Neptune said:
Thanks. So 1 bypass and not 4?

Yes, only 1 bypass needed however many bulbs.
Pins 0 and L used:

Neptune · Dec 6, 2021

Avo Mk8 said:
Yes, only 1 bypass needed however many bulbs.
Pins 0 and L used:

Sorry for the incessant questions and thanks for all your help. My light fitting will have 4 wires. Like this but also the “out” as this is not the end of the lighting circuit:

[ElectriciansForums.net] Shelly 1L Installation

Think I will need some wago for this bypass.

Avo Mk8 · Dec 6, 2021

Neptune said:
Sorry for the incessant questions and thanks for all your help. My light fitting will have 4 wires. Like this but also the “out” as this is not the end of the lighting circuit:
Think I will need some wago for this bypass.

For some reason I thought the Shelley was going in the switch back box, but this is fine.

On second thoughts, maybe you are only talking about the bypass going in the ceiling rose?

Sorry, edit
Are all lights to be controlled simultaneously?
ie Just one wall switch wired to the Shelley.

If so, might it be possible to use a bigger ceiling rose and put the Shelley there? And then you have a neutral available!

Having Wago's to hand would be a good idea!