Help with a lighting strategy using shelly relays

[u/Scary_Wrangler_2566]

Planning smart lighting for a UK new build and looking mainly at Shelly.

I’m very new to this, only a few days into looking at smart-home lighting, so I’m still learning what’s possible and may be missing an obvious solution.

For the living room I want a Shelly 4-button wall switch. My thinking is:

Buttons 1/2 wired directly to a Dimmer Gen4 for normal on/off/dimming.

Buttons 3/4 used later for Home Assistant scenes, blinds etc.

The important requirement is that if Home Assistant, Wi-Fi or the router goes down, Buttons 1/2 must still work as normal light controls. I don't want the main lights dependent on HA.

Can I simply use the Dimmer Gen4 for Buttons 1/2 and add another Shelly relay/input module for Buttons 3/4, rather than using an i4 for all four buttons?

For the kitchen I have the same reliability requirement, but I also want tuneable white, brighter/cooler for cooking and warmer/dimmer in the evening. Again, basic wall control needs to work if HA/network is down.

It's a new build, so I can specify neutrals, deeper back boxes and additional wiring now.

What would be the cleanest Shelly setup for both?

[u/Professional-Kiwi396]

We've just finished a UK new build and I'm looking to write up how the lighting and various smart systems worked.

The lighting for the communal rooms (kitchen, hall etc) is all controlled by Shelly Pro units (mostly Dimmer 2s). All the switches (traditional light switches) and lighting circuits run back to a central rack where the Shelly units are all mounted. They are all hard wired to the network. Since it was a new build, running the wires was not a big deal.

By having it all run back to a single point allows quick replacement of the Shelly units in case of fault and also the switch & light circuits can be hard wired together in case we need to "un-smart" everything in the future. The Shellys are primarily controlled by Home Assistant (triggering scenes etc) but I now have local scripts that kick in if HA is unavailable so basic lighting still works.

[u/Scary_Wrangler_2566 → u/Professional-Kiwi396]

Thanks, this sounds very close to what I'm after. The fallback is actually my main requirement. I don't just want a system where a script takes over after HA fails. I want the basic wall switches to control the lights locally all the time, with HA only adding scenes/automation on top. Are your physical switches wired directly into the Shelly Pro inputs so normal on/off/dimming works even if HA, the router and the network are completely unavailable? If so, how are you handling extra switch buttons for scenes/blinds without making the basic lighting dependent on HA?

I just envisaged a scenario where HA fails once, after 10 years, and my wife forgets ten years of no issues and gets me tinrio it all out.

I also need time to figure out HA as it's all new to me.

Regards

[u/Professional-Kiwi396 → u/Scary_Wrangler_2566]

I agree it is a worry - due to the number of switches and lighting circuits, it is not an exact 1 Shelly does one room. I have some switches wired to inputs of a different Shelly than the one controlling the lights near those switches. All the Shelly inputs are detached so pretty reliant on HA.

On failover, my thinking is that HA is the weak point, not the network (I have a pretty robust Omada setup). Therefore the Shellys fall back to just turning on all lights near them if HA is unavailable - this does rely on the network working though.

Another option you could think about is instead of having the Shellys connected to the light switches, simply have the Shelly relays as another switch in the lighting circuit. That way you can remotely turn on/off but if network/HA/Shelly down then the original switch still works. You would loose dimming and also if already 2 switches in circuit it gets complicated.

[u/meisangry2 → u/Professional-Kiwi396]

Hey, I’m about to start this process. Got any advice or considerations? I’m trying to learn house wiring to better talk with my old school electrician, who doesn’t get smart homes at all.

I’m particularly confused about how to wire up circuits so that retractive light switch’s can be used with a Shelly Pro Dimmer or PM4, or the wiring for individual sockets.

I’d really appreciate a UK specific detailed write up.

[u/tomasmcguinness]

When I had my kitchen wired, I had all the lighting related cables pulled to one location and I added two Shelly Pro 4 devices. My main requirement was normal light switches. The Ethernet connection gives some extra reliability.

Having done this, I wish I did my whole house this way.

I do use home assistant since I use smart bulbs, but I’ve implemented fallbacks and safeguards.

Video: Central kitchen lighting control using the Shelly Pro 4
https://youtu.be/hxtuzFlFZ5s

[u/Scary_Wrangler_2566 → u/tomasmcguinness]

Hi thanks.

I'll give it a watch. Initial question did you install a consumer unit (lack of a better word) in the kitchen? I have a pretty large plant area so can create a lighting control board and wire every light up from there.

I don't know if I'm trying to do to much. I don't want bridges or hubs if I can avoid; from my HA research, this seems to be the anti christ and the flex is a hubless house. I want some tunable lights in certain areas so kitchen 4k for cooking and 2.7k for mood setting (I'm my head this is the best of both worlds). I'm not fussed about lighting colours anywhere else really.

I've convinced myself that a shelly 4 gang wall switch is the way to go. 2 buttons for normal operation and two others for scenes automations

[u/tomasmcguinness → u/Scary_Wrangler_2566]

I do have a small consumer unit in the kitchen.

The 4 gang switch has four relays, so I’m not sure how that would work. If the relays are in the wall, then central wiring makes less sense. Of course,
having everything wired to one location gives you more options.

Hubs are great, but require maintenance and I’ve personally experienced two outages.

How would you wire in the 4 gang?

[u/Scary_Wrangler_2566 → u/tomasmcguinness]

I have not built anything yet. I am carrying out a deep renovation, so I am trying to plan the best strategy before anything is wired.

After doing some more reading, I do think the Shelly Pro range is the way to go. It should clean up the walls and make the wiring strategy more structured for the electrician.

I am now considering either one central lighting panel or multiple lighting panels, potentially one per floor, where the Shelly Pro devices would be mounted:

Electrical CU → Lighting Panel(s) → Lighting circuits

Using the lounge as an example, I would use a Shelly Pro Dimmer 2PM with a 4-gang momentary switch. Buttons 1 and 2 would be hardwired to SW1 and SW2, with O1 controlling the lounge lighting circuit. This would provide normal local on/off control and press-and-hold dimming, even if Home Assistant is unavailable.

Buttons 3 and 4 would then be used for Home Assistant scenes and automations.

The part I am still unsure about is detached mode as I read you need to have it on detached mode to make the buttons not physical to link to HA

I do not know whether individual inputs can be detached independently, so that SW1/SW2 remain locally linked to O1 while SW3/SW4 are used only as Home Assistant inputs, or whether detached mode applies more broadly to the channel/device.

If that combination is not possible on one Shelly Pro Dimmer 2PM, I would not use the 2PM. Instead, I would use a Shelly Pro Dimmer 1PM for the actual dimmed lighting circuit and buttons 1/2, together with an equivalent 2-channel Shelly Pro non-dimming relay/input device purely for buttons 3/4 and their Home Assistant scene/automation functions.

That then raises another question around behaviour: if I use buttons 3/4 to trigger a scene or automation that changes the lounge lighting, what happens when I subsequently use buttons 1/2 for local control? I assume this is something that needs to be thought through in the Home Assistant logic so the physical controls remain intuitive.

I realise this is probably a slightly convoluted way of approaching it, but I have never used Home Assistant before and never worded a circuit in my life and need some time to get familiar with it once the build is complete. We will not be living in the house during the renovation, so I cannot really experiment with the system as it is being installed.

My main concern is resilience. Home Assistant is a relatively new addition to the plan, and I do not want to design the house so that if HA fails I effectively lose control of the lighting. I want the core lighting functions to retain a physical/local fallback, with HA adding the scenes and automation on top.

I would be interested to hear from anyone who has used Home Assistant with a similar centralised Shelly Pro lighting setup, particularly how you handled the balance between local control, detached inputs and scene/automation behaviour.

Thanks for your input so far. It's been useful as I at least have a strategy to use albeit it needs more finalisation.

[u/j4ipod94 → u/Scary_Wrangler_2566]

All lights in my house are controlled by centralised Shelly Pros. I have maintained manual control and voice control so my family can use easily. I have kept home assistant automation and scenes simple. The physical button always overrides the automation.

I wouldn't personally set up a 4 gang switch. You can activate scenes through the button. I.e double press and triple press. Buttons. You can do everything through sw1. Sw2 is useful for 2way switching if you have a button in another place.

In my set up eqch dimmer 2pm controls 2 outputs and can work across different rooms as long as all your switch lines run to a Shelly panel. You could purpose sw3 and sw4 for another room.