Assuming the bulb is incandescent and the switches are 1 -2 - 3 turn on switches 1 and 3 - wait 10 minutes - turn off switch three go to the attic - if the light is on, switch one activates the lamp if the light is off, feel the bulb if it is warm, switch 3 activates the lamp if it is cold, switch 2 activates the lamp. SushiSlayer