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Review: The Lutron MS-OPS2 occupancy sensor switch

I installed a Lutron occupancy sensor switch this weekend. It detects you entering the room, turns the lights on, then turns them off five minutes after it detects nobody is in the room. The timeout period is adjustable. It comes in four models: MS-OPS2-WH (white), -AL (almond), -LA (light almond), and -IV (ivory) and retails for $29.

Installation was surprisingly easy–it took about 15 minutes, which is about how long it takes me to change a regular switch, and unlike most models in its price range it works with modern CFL and LED lighting, but I recommend some prep work ahead of time.

The quality of life upgrade

It solves a real problem. Most days when I come home, every light in the house is on. I know why. I have two young boys who can’t reach the lights, so they can’t turn them off and on themselves. But besides that, they’re demanding. My wife goes down to the basement to get something, turns on the light or lights she needs, comes back upstairs, and can’t turn the lights off because her hands are full. The bathroom lights stay on most of the time because the boys can’t reach. And so on.

I go back around and turn the lights off, but let’s face it. Even though I make a conscious effort to turn off lights, several unoccupied rooms in the house stay lit even when I’m home.

A caveat

Lutron claims its switches can save you up to  $25 a year. We’ll talk about that math in a bit.

But there’s a caveat. Before you buy one, double-check your light switches. Most automatic switches require a ground connection, and it’s only been in relatively recent years that electrical codes have required ground wires on light switches. In older homes, you may find there is no ground wire. If the light switch is in a metal box, the metal box may be grounded, but you can’t necessarily assume that. If there’s no ground wire, use a different switch.

My home dates to the early 1960s but has been renovated at least twice. Some of my switches have the ground connection and some don’t. I have metal boxes at many of my switches, which are supposed to be grounded. In some cases, I can see they are, but you can’t assume all metal boxes are grounded. At my rental house, built in the 1950s, some are and some aren’t.

So check first, before you buy a bunch of switches, find they won’t work for you, and have to return them.

The upside to the MS-OPS2, as opposed to many others like it, is that you only need the two wires that go into the switch, plus ground. Many similar switches need the white neutral wires too, in addition to ground of course.


Installing is actually a little bit easier than swapping a conventional switch. Turn off the breaker box (very important), then remove the old switch, straighten the wires, attach one wire from the old switch to one of the black wires on the Lutron with a wire nut, then attach the other wire from the old switch to the other black wire with a wire nut, then attach all of the bare ground wires in the box to the bare ground wire on the Lutron and the green wire. In some cases you may need a bigger wire nut than the ones the Lutron includes.

You can manually turn the switch off and on using the big pushbutton. I put one in my basement, and it detects me from 15 feet away. It makes an audible click when it turns on the lights, but the click sounds much like any other light switch. The last regular switch I bought is quieter than the Lutron, but it doesn’t bother me. I put another one in my L-shaped kitchen. If I can see the switch, it sees me and turns on the light. Opening a door won’t trip the switch, as it uses an infrared sensor that a door won’t trip.

You can adjust the default settings using instructions included in the package. For example, you can adjust the timeout to 20 minutes if you’re concerned about the longevity of your CFL bulbs. You can also enable a daylight sensor, so it doesn’t automatically turn the lights on if there’s already a lot of sunlight in the room.


To figure out what the Lutron could save you, estimate how many hours a particular light stays on. Calculate the wattage of the bulbs. Multiply those two numbers, then multiply by 365. Divide that number by $1,000 and then multiply that number by what you pay per kilowatt/hour of electricity. Ten or 11 cents is a good estimate, if you don’t know.

In the case of my bathroom, the equation would be 8 (hours) * 45 (wattage) * 365 / 1000 * .11. I get $14.45.

With the Lutron, the bathroom lights would probably be on less than 2 hours per day. We’ll round it up to 2. So now the equation is 2 (hours) * 45 (wattage) * 365 / 1000 * .11. I get $3.61, for a savings of $10.84 per year, which means it would pay for itself in less than three years. You’ll realize additional savings from the increased life expectancy of the bulbs and a slight decrease in your cooling costs during the summer months. If the life expectancy of the bulbs doubles or triples, $2 per year is a reasonable rough estimate. The switches really helped me drop my power usage in 2011.

If you use bigger bulbs than me, the payoff would be faster. And if you still have incandescent bulbs, the payoff would be much faster.

If your home wiring allows you to install these switches without much difficulty, they’re a good energy-saving and quality-of-life upgrade. The only thing you’ll need that doesn’t come in the package, besides a screwdriver and needle-nose pliers of course, is a GFI/decora-type plate the same size as the one it’s replacing.

You can look at it as a good investment, too. I can’t think of many things–let alone things that cost less than $30–that give me a 30% return on investment every year. The cost of bulbs will come down over time, of course, but the cost of electricity is going nowhere but up.

More energy saving ideas

I’ve done a number of other things to help me save energy over the years. Most are pretty inexpensive. I installed thermal blinds and thermal curtains. Then I insulated my electrical outlets and added child safety plates. Of course I use LED bulbs. I also insulated my hot water pipes.

My electric usage dropped 19 percent in 2011, so these things work.

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