Shelly 1 Gen4 vs Shelly 2PM Gen4

The Shelly 2PM Gen4, which switches two circuits, adds energy monitoring and includes overvoltage, overcurrent and overpower protection, with a slightly stronger rating. The Shelly 1 Gen4 costs less and is the only one with dry-contact and wet-contact modes.

The Shelly 2PM Gen4 has two relay channels and per-channel energy monitoring, while the Shelly 1 Gen4 has one channel and no metering but supports dry-contact and wet-contact wiring.

The Shelly 1 Gen4, because dry-contact mode gives a voltage-free switch, which is what most boilers, gate controllers and low-voltage inputs expect. The Shelly 2PM Gen4 does not list that mode.

The Shelly 2PM Gen4, reporting consumption on each of its two channels. The Shelly 1 Gen4 switches without metering.

The Shelly 2PM Gen4, adding overvoltage, overcurrent and overpower protection to the overheating protection both provide.

Anyone controlling a single circuit at the lowest cost, or who needs dry-contact or wet-contact wiring for pulse triggers, a boiler or low-voltage equipment.

Anyone with two loads in one backbox who wants both switched and metered independently, with the most complete set of electrical protections.