Should every DIY sensor have a physical cutoff?

I keep coming back to a design question in my Raspberry Pi and microcontroller builds: if a gadget can hear, see, or measure the room, should its sensor have a clearly visible physical power cutoff?

Software mute is convenient, but it is still software. Raspberry Pi’s audio documentation describes some HATs where software controls both the mute state and indicator LED. Camera shutdown can also be controlled through GPIO on certain Compute Module setups, but that is not the same as a user-accessible switch.

On one desk prototype, I assumed a muted microphone was harmless, then watched the input meter move because the board was still powered. Probably a wiring mistake, but it changed what “muted” means to me. Real cutoffs cost enclosure space, labels, wiring, and convenience, especially for unattended environmental logging, and need careful design to avoid power through signal lines. Do other makers consider physical disconnects essential, or unnecessary overengineering? Examples and counterarguments welcome.

I’d call it a useful boundary, not a universal security guarantee. If the switch genuinely removes sensor power, compromised software has fewer options. But the circuit still needs review: signal lines can create unintended powering paths, and a decorative LED proves very little. I’d reserve cutoffs for microphones and cameras unless the threat model says otherwise.

For a camera or mic, yes. For a temperature sensor in a basement, probably not. I’d use a load switch or MOSFET rather than route sensor current through a panel switch, then document the power path. The enclosure and connector count grow quickly once every tiny sensor gets its own isolated control.

The visible switch may matter socially even when users never touch it. “Muted” is an abstract status; an open circuit is easier to explain to a visitor. But labels and placement are part of the design. A cutoff hidden behind the box is technically physical and practically useless.

My counterargument is maintenance. Every extra switch becomes another failure point, another hole in the enclosure, and another thing someone forgets to turn back on. I’d make camera and microphone cutoffs standard, then stop pretending a humidity sensor deserves the same ceremony.