Pros: two outlets, grounded, multiple control modes for the outlets
Cons: time setting not very precise, some setting pins sticky
Simple timers are fine for single installations, but have built-in limitations. One is that neither timer nor outlet is grounded; another is that most only have one outlet. For my seed-starting station, I have both a grow light and a heating mat. The mat needs to be on 24/7, but the plants only need light 14-16 hours per day. The solution was an inexpensive Dual-Outlet Timer I picked up a Lowe's: their house brand, a Utilitech #0143158 - made in China and distributed by The NCC (their model LW61204).
This mechanical timer is a white plastic box measuring about 3x4x1½ inches. There's a 24-hour clock dial on the face, and one side has a grounded (three-prong) outlet. On the other side are a toggle switch and an ungrounded outlet. There's a grounded male plug on the back. The clock face is surrounded by ninety-six short pins, each of which controls a fifteen-minute interval. If the pin is pushed in, the timer is ON; if the pin is out, the timer is OFF. This configuration allows multiple ON-OFF cycles over a twenty-four-hour period. A hinged cover protects the clock dial to prevent accidental changes to the settings.
Like most mechanical timers, current time is set by rotating the timer dial to line up with a crude clock, which isn't very precise. There is also a small switch to override the timer.
The operation of the two outlets is controlled by the three-way toggle. The options are both outlets controlled by the timer, one outlet controlled by the timer and the other ON, and one controlled by the timer and the other OFF. The grounded outlet is always controlled by the timer. I have mine set so the grow light is on the timer and the heating mat is always on.
The Utilitech #0143158 has separate ratings for its outlets. The grounded outlet is rated at 125V and 15A for appliances (1850W) or 10A for incandescent bulbs (1250W). The auxiliary plug is rated for 1.5A (180W). It is not suitable for use in wet areas. The spec sheet claims that the timer has a 1/3-HP motor, or about 250 watts; but that seems high since clocks only draw about 5W.
Programming is straightforward, though the on-off times aren't terribly precise. Most, though not all, of my pins moved easily and positively. Wording of the instructions for setting the toggle switch is somewhat clumsy (easier to puzzle out in Spanish than English). The timer functions well and has kept accurate time as long as I've had it plugged in.
If I were concerned about precision timing, I'd ‘ve bought digital. If I were concerned about potential burglars noticing that the lights go on at the same time every day, I'd've bought a fuzzy logic model. All I wanted was a simple two-outlet grounded timer, and the Utilitech #0143158 has proven sufficient to my needs - and that's fine by me.