Kasa HS220 Neutral Wire Required? Yes — With One Caveat Worth Knowing
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Short answer
Yes
Yes, the Kasa Smart Dimmer Switch HS220 requires a neutral wire to install.
TP-Link's own installation documentation for the HS220 lists a neutral wire as a required connection at the switch box. The dimmer needs constant low-level power to run its own electronics and Wi-Fi radio, which it draws through the neutral conductor rather than pulling parasitic power through the load like some old-style dimmers do.
If your switch box only has the classic two-wire setup (hot and traveler/load, no neutral bundle), the HS220 is not compatible as-is. This is common in older homes built before neutral conductors were routinely pulled to switch locations.
What to do instead
Use a non-contact voltage tester (power off first) to check for a bundled neutral wire, usually a white wire capped off in the back of the box. If there is no neutral present, you'll need an electrician to run one, or you should look at a no-neutral-required smart dimmer instead - the HS220 is not the right product for that box.
