020927testlamp

Test Lamp from Lucifer

tinmoorthy

We had a friendly neighborhood electrician who was Lucifer. We called him whenever the fuses went off. Lucifer was our light bringer. I always wanted to be an electrician after him. He carried with him a test lamp, brightly colored VIR wires, an incandescent bulb in the original corrugated cardboard packing and a roll of insulation tape inserted on to the bulb holder. His life appeared simple, bug-free and always cheerful

Lucifer specialized on miracles. Reluctant fans would turn on after his visit. Air-conditioners would choose to become cool. We spent hours observing him at work. In return Lucifer would show his treasures. He maintained a small warehouse in a garage near my house. Amongst many other things he had, I wish to talk now about his test lamp. Lucifer's special lamp was mounted on small wooden board with a three pin 5 Amperes plug connected to it. No, it was not intended that the light would be energized when you connected the plug to the power supply. In order to do that you need to connect a small piece of wire between two binding posts that showed on the top of the board

"OK, Luci. You could have provided a switch. That would have been elegant" -- I remarked

"Some time I like to insert a fuse wire between the posts just to make sure I do not exceed my quota of the current"

"Does anybody use a fuse wire still?"

"Yes, Master, Still. People like me. We grade the fuses and do not allow any thick conductor that we come across to be deployed as fuse. Let me come back to the binding posts after I tell you the rest of the story" -- told Lucifer

"OK, then, I am all ears"

Lucifer connected a small piece of wire to the posts, inserted a 25 Watts bulb on the holder and pushed the plug to a wall socket. The lamp came on

"What is so great about that?"

"You can deploy this as a portable lamp wherever you need --- say for attending to the bottom of the car, or lighting the dark attic or simply as a reading lamp by the bedside. You can switch the lamp off by disconnecting the wire between the binding posts. Or as you suggested with a real switch between the posts. More interesting than that is connecting an electronic step-less regulator (of the variety used with the ceiling fans). You will then a control of the output current through the power socket. For such accommodating generosity only, the binding posts were envisaged"

"Bravo Lucifer, that is sure interesting" -- I remarked. He pulled the piece of wire out. The lamp went off

Lucifer pulled two test probes from his trunk. A test probe is a long colored cable with a stiff insulated pin at the end. Black and red are the only two colors admitted for the cables. Red signified hot or positive while the black indicated neutral or zero potential. The binding posts received the probes

"Well, what do you do with the probes?"

" I can now use them for doing a continuity check". He took out another bulb from the table. He touched the terminals of the bulb with the probes. Both the bulbs glowed dull. The two bulbs are in series and that is the reason why they are duller than normal -- he would explain

"Of what use is this test?"

"There will be no glow if the bulb under test has conked off", he said. Generally you would find this arrangement at the shops for testing the bulbs before the sale. He then pulled out an aluminum (tube light) starter and performed the same test again. The light on the board came on and off -- but with full brightness. The glow (of the neon) inside the starter and that of the bulb outside were exactly out of phase, that is to say mutually exclusive. This shows the starter is working fine. He promised to explain the function of the starter later

I offered to try myself. He warned -- be careful, the probes carry the line potential. I still managed to get them shorted -- and the bulb on the board glowed in full fury

"This is square one," said Lucifer smilingly, "because this is how one normally confirms the sane working of any continuity testing jig". He added whenever you wanted to test the continuity of any device and providing the device under test can take this 220 Volts AC (without damaging itself) you can extend the test probes to its (two) terminals. An approximating short inside will be indicated by a bright glow of the bulb. For example a mixie (swithed on). Devices that take much less current will make the test bulb glow dull. For example a battery eliminator. For connecting those devices that terminate on two or three pin plugs readily, I have provided the corresponding socket here," he would add further. He added the same probes help in determining if an installed wire already carries ground (earth), line or neutral

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