Dim lights when the TV turns on
Automatically dim the living room lights when the TV turns on, and restore them to their previous level once the TV turns off.
Best for: A living room with dimmable smart lights and either a smart plug with power monitoring or a TV/streaming device that reports its power or playback state reliably.
Not for: A room where lights need to stay bright regardless of what is on screen, or a TV whose power state cannot be read reliably by the platform.
Why this exists
Dimming the lights by hand every time a movie starts is a small chore that is easy to skip, and it means the room does not settle into a consistent viewing setup. Automating it removes the extra step, and restoring the previous brightness afterward avoids leaving the room dim once viewing is over.
What I used
| Job | Good enough | Never think about it | Notes |
|---|---|---|---|
| Detect the TV turning on | Zooz ZEN15 Power Switch | No personally verified recommendation yet | I use the ZEN15’s power readings to distinguish standby from the TV being on. Measure the TV’s actual draw before setting thresholds. |
| Dim the living room lights | TP-Link Tapo S505D Matter Smart Dimmer Switch | UltraPro Z-Wave Long Range Dimmer | Requires a dimmable fixture and a switch rated for the load. |
See recommended gear for the job-first checklist. Product links on this page are direct, non-affiliate Amazon links. Product recommendations and any future affiliate relationships are explained in the disclosure.
Logic
- Trigger: Power draw on the TV’s smart plug rises above a threshold, or the TV/streaming device reports it is playing.
- Conditions: The current time is after a chosen hour, such as sunset, if daytime dimming is not wanted.
- Action: Save the current light brightness, then dim the living room lights to a low level.
- Wait / timeout: Keep the lights dimmed until the stop condition is met.
- Stop condition: Power draw drops below a lower threshold, or the TV reports it has stopped, for a couple of minutes.
- Manual override: The physical light switch or app always works to change brightness directly.
Setup notes
- If using power monitoring, test the TV’s actual wattage in both standby and active playback so the “on” and “off” thresholds are set apart from real values, not guessed.
- Add a short delay, such as thirty seconds, before dimming so a menu screen briefly drawing similar power does not trigger it.
- If using a smart TV or streaming device signal instead, confirm the platform reads its state reliably before relying on it daily.
- Save the current brightness before dimming so the lights can return to where they were, rather than always resetting to one fixed level.
- Require the “off” condition to hold for a couple of minutes so a brief pause does not restore full brightness mid-movie.
Advanced features
Daytime versus evening dimming
Use a lighter dim, such as 40 percent, during the day for glare control, and a deeper dim, such as 10 percent, in the evening once natural light is gone.
Skip dimming during activity
Add a condition that skips dimming if recent motion has been detected in the room, so lights stay normal while people are still moving around rather than settling in to watch.
Failure modes
- Lights dim when only the menu is open: Raise the power threshold or add a longer delay before dimming; consider switching to a TV-state trigger if available.
- Lights do not restore when the TV turns off: Confirm the “off” threshold or state check is set below actual standby power, and that the previous brightness was saved before dimming.
- Lights dim during the day unexpectedly: Add or correct a time-of-day condition if daytime dimming is not wanted.
- TV state reported inaccurately: Check the TV or streaming device’s network connection and platform integration; power monitoring can serve as a fallback trigger.
Done when
- Actual TV wattage has been tested in standby and while playing.
- The lights dim reliably once real playback starts, not just when the menu is open.
- The lights restore to their previous brightness after the TV turns off.
- Daytime behavior matches what the household wants.
FAQ
Should I use power monitoring or a smart TV signal as the trigger?
A compatible power-monitoring plug works with many TVs, but can be fooled by a menu screen drawing similar power to active playback. A smart TV or streaming device signal is more accurate if the platform supports it reliably.
Why does the TV menu sometimes dim the lights by mistake?
A power-based trigger cannot always tell a menu screen from active playback, since both can draw similar wattage. Raising the power threshold or adding a short delay before dimming reduces this.
Will the lights go back to their previous brightness after the TV turns off?
Yes, if the previous brightness is saved before dimming and restored once the TV has been off for a couple of minutes, rather than always returning to one fixed level.