[fletch]

If you experience this problem, your Christmas lights are series-wired. In series wiring, each bulb acts like a fuse: if one bulb burns out, the circuit is broken. Some sets have a shunt wire that allows the electricity to pass into the next socket if one bulb burns out, but no series-wired set will work if a bulb is removed from its socket. If your set does not have a functioning shunt wire, all you need to do is locate the missing bulb and replace it in order to close the circuit.

E.H. Scott of Hofert Co., a leading supplier of Christmas trees and decorations, says that many consumers are confused about how to replace bulbs in series-connected sets. To find the appropriate bulb, you merely divide the voltage standard (120 volts) by the number of bulbs in the set. If you have a set of 20 lights, you would need a six-volt bulb.

So If you are using 3 bulbs you will need 40 watt bulbs if you are using 4 bulbs you will need 30 watt bulbs and so on.... I hope that this helps.................... John