Porch Lighting

Watts measure how much power a lamp consumes. Lumens measure how much light comes out. With incandescent lamps the two tracked closely enough that everybody learned to shop by watts, and then LEDs broke the relationship completely. A lamp drawing nine watts can outperform one that used to draw sixty.

So the useful spec on the box is the lumen figure, and the useful second number is lumens per watt, which tells you how efficiently the fixture does its job. A rough starting point for a living space is around twenty lumens per square foot, with kitchens and shops wanting considerably more and bedrooms wanting less.

We plan a room on delivered lumens at the surface where you actually need to see, which is the counter or the desk, not the ceiling. That is a different calculation than total output, and it is the one that decides whether a room works.

There are two ways a light gets wired, and which one you have decides what is possible later. Power can arrive at the switch box first and continue to the fixture, or it can arrive at the fixture and drop a switch leg down to the switch. Both are correct and they behave very differently.

The second one is the problem for modern devices. In an old switch loop the box holds only two conductors and no neutral, and almost every smart switch, timer, and occupancy sensor needs a neutral to run itself. Code now requires a neutral at most switch locations for exactly this reason, but that requirement is newer than most houses here.

We open the box and look before promising anything about a smart switch. Sometimes there is a neutral behind a cap that somebody never connected, sometimes the fix is a short pull, and sometimes the honest answer is a different device.