[dboreham]

Powerline Gigabit Ethernet is a thing, but it's bordering on wireless (uses the power wiring as a "guideline" as to where its RF energy should go). This makes the network attachment unit costly and adoption low. For most applications WiFi is cheaper and more convenient. Anyone who wants really solid connectivity will lay Cat5.

[paulfurtado]

The use case here is turning an outlet or light on/off, so latency matters, but it requires nearly zero bandwidth (assuming that you're not talking tcp). Granted, x10 security cameras exist.

x10 speaks a protocol designed for this purpose and requires a base station.