Hmmmm – not sure if this is in the right forum but it didn't really seem to fit into the lighting ones. If you have ever bought a dud lamp, this may be of some help: On several occasions now I have purchased new lamps only to find that some are duds. Now on one occasion I had purchased a couple of lamps for a new light and when it didn't strike I was a little concerned. So I used another new lamp, with the same result. I then checked the voltage at the lamp base and the unit was working. So I did a continuity check on the lamps and both were duds. Fortunately, the supplier was willing to exchange the lamps, as I returned them to him on the same day. To look at them, there was no problem. No discolouration of the glass and the filaments were intact. As I usually buy more lamps that I need (to ensure I have spare stock) this led me to the question "what if this had been a lamp that had sat in my workshop for 3 months?” Would the supplier be so willing to replace it then. What I decided to do was build a simple little box that I could leave in the van and test the lamps at the counter when I buy them. So this is what I did. I took a small plastic box and cut a rectangular slot in it (large enough to fit the terminals of a Par 64 lamp in). I then took a section of breadboard (I am not sure what it is called in the US but it is essentially circuit board with parallel tracks and pre-drilled holes in it, which is used to construct simple circuits on) and mounted a section on the inside of the box, with the copper tracks facing outwards. I cut a line across the tracks in the middle (running vertical across the horizontal axis) of the slot, so that I had two separate copper pads (I also tinned them so they wouldn’t corrode). To one pad I connected a 9V battery, which I connected to a LED (mounted into the lid). The other side of the LED was connected to a 220ohm resistor, and in turn to the other pad. This allows me to touch the terminals of most lamps that I purchase onto the pads and immediately see if I have continuity. It is simpler that using a multimeter and fits into my pocket. If anyone wants to see a picture of it, I am happy to send you one. You could probably make something a little more compact or better, but this was made out of materials at hand. Cost effective and efficient! The supplier was a little surprised when I started testing the lamps as he was putting my order together but when I explained why, he understood. Especially when on the second time I used it I found a faulty Par 36 lamp. Since then I have had a few lamps that have been found to be faulty and some of them were in fact ones that I bought because I was there and I knew I only had one or two left. These would have been to ones that sat in my workshop for a couple of months before being found out. Hope this is helpful to someone.