Step 1 : Description


Want a cheap, simple, foolproof blown bulb locator (USA/Canada only) for $3.78? Simply buy a "contact" type voltage probe like the one at http://centralonlinesales.com/show_Product.asp?ID=832

Cut the head off a pin. File the chrome off one side of the screwdriver shaft and off half the pin and solder the pin to the screwdriver. You need a 100W+ soldering iron. Solder quickly and dip the tip in water immediately after soldering so the plastic case doesn't melt.

Cover the soldered area with heat shrink so only about 3/8" of the pin is exposed. Alternatively just fasten the pin to the end of the tester with electrical tape or heat-shrink.

Shove the pin up the back of a bulb in the middle of the string while touching the tab on the side of the tester. Push it up one side between the wire and the case and it will touch the metal lug inside. If you are on the "live" side of the blown bulb the LED will come on. If on the dead side it won't. Go half way along and half again until you find the blown bulb.

With the blown bulb the LED will come on when you probe one side of the bulb but not the other side. Should take about 10 seconds to locate the fault.

Much more reliable than proximity sensors and much simpler than high-voltage buzzers since you do not have to remove any bulbs. Just take care not to touch the pin while it is in contact with the high voltage wire. (Should be impossible if you have covered most of it with heat shrink as outlined above.)

Note that this will only work in the USA or Canada where you run direct from mains where one side is grounded and one side is live. In Oz where we run from transformers it doesn't work because there is no "dead" side so the LED comes on no matter where you test. Note also that the voltage probe must be a "contact" type not a "proximity" type.