VOLTAGE CLIMBING = ???
Chasing area lights-out after my predawn lights walk on Monday. I measure the voltages for the maintenance log as an indicator of trouble.
This gate light (fluo. PL 13 lamp) started with a voltage of 40 and slowly climbed. At around 70 v I got bored and stuffed a new lamp in. Of course it didn’t light. We have some issues here.
I will pull the light tomorrow and see what the incoming voltage is – but – what does a slowly climbing voltage at the lamp socket indicate?
(Legacy wiring! Keeps me in tools!)
The ToolBear
“Never met a man who couldn’t teach me something.” Anon.
Replies
It could idicate that you don't have any "real" voltage. The circuit is open and you are probably reading a capactive, inductive or a very high impedence leakage induced voltage on the line that supplies such a low amount of current that when you first hook up your meter it sucks what little voltage/current is available to charge internal meter capacitance and as the meter capacitance slowly fills up, the voltage slowly rises. The input impedence of your meter will determine to what level the voltage will rise.
Put on you Sherlock Holmes hat and look for an open in your circuit, starting with breakers and broken wires. Troubleshooting is a fun game and the answer is usually very obvious after you find it ;-)
Well, the ballast can limit voltage to maybe 40 volts in some circumstances, but generally that will only be with a bulb installed and lit. With the bulb dark or removed the voltage should be near line voltage.
When I see voltage in the range from about 25 to 70V I figure that it's probably stray pickup on a line that isn't connected. With this sort of thing you can see the voltage fluctuate quite a bit based on where you stand, what other circuits are on or off, etc.
Try putting a small incandescent bulb -- say 15 or 25 watts -- in parallel with your meter. It'll short out any stray pickup.
-- J.S.
I will add one to the kit. The ToolBear
"Never met a man who couldn't teach me something." Anon.