…continuedHome Lighting Guide
When correctly oriented, both are very effective at restricting a direct line of sight to a floodlight's front surface, especially when the observer is at a large angle to the beam's centerline. This is often the case for lights in neighboring yards. Cliff Haas's simple sheet-metal shield provided a substantial reduction in the light spreading outward from one side of a floodlight, and this asymmetric pattern gives some control to the homeowner illuminating an area close to the fixture. The clip-on shield created by Susan Harder offered a more uniform reduction of the floodlight's angular coverage. At the 0.5-foot-candle level, it reduced the light cone from the General Electric 100-watt halogen floodlight from 116° to roughly 70°.
It's not unusual to find porches, especially on older homes, illuminated by conventional incandescent bulbs fitted to simple, nonrecessed ceiling sockets. Unlike floodlights, the illumination from these bulbs is not aimed in a particular direction, and as such, any direct line of sight to these bulbs is vexing to observers. In such cases a do-it-yourselfer can often fabricate an effective shield but important safety issues involving heat must be considered.
For example, we made a seemingly simple shield by removing the top and bottom from a 1-pound coffee can and fitting it around a standard 100-watt incandescent bulb mounted in the temporary ceiling fixture used for our tests. Within minutes there was enough heat buildup to melt a plastic fitting that had remained unscathed during hours of previous tests. Furthermore, insidious heat buildup behind a lighting fixture can be even more dangerous, damaging electrical wiring and creating a potential fire hazard. Any shield near an incandescent bulb needs to have provisions for ventilation and heat dissipation.