
Originally Posted by
Alaric Darconville
If they are all controlled from the same switch, that could cause problems in itself. The surge current when all six lamps are energized at once can exceed the capacity of the switch to handle (some switches are rated for 600W max incandescent load, however*) and the surge may also cause an older breaker to trip.
This is because the filaments pass more current when cold/warming up than when they are at their operating temperature.
Also, if one of the bulb blows, it can cause arcing to occur inside the bulb. Add that arc and resultant current draw to the remaining 500W, and that could trip the breaker before the bulb's own fuse blows (yes, many incandescent bulbs have an internal fuse). Also, considering that many bulbs blow when you first apply power, you can see how you can have the massive cold-filament surge current combined with the arc.
So now your problem is that you're exceeding the fixtures' individual specifications and you may be exceeding that branch circuits specifications.
And if it does catch on fire, your insurance company may choose to deny your claim based on exceeding the fixtures' specifications alone.
*The max incandescent load takes into account the cold filament surge current