How can I test the output of lighting ballast?

[kengineering]

It seems simple enough but when I try to test the voltage my meter just zones out. I tried another,, it froze-up, shut down and had to be reset. The last one in the shop blew a fuse. What gives? Ken

[chabby]

this is a high voltage , becaus e it is attached to a capacitor which acts as a voltage doubler...Try a high voltage meter .. T thinh the output voltage is about 700 volts

[Paulajayne]

If a ballast is blowing the correctly rated fuse then it is more than likely "Kaput".

Paula

[Electrocoolman]

What sort of light.....fluorescent, sodium, mercury, halide etc.

Best method is unpowered/disconnected and do a resistance check and comparison against a known good one.

If its a sodium / halide, the starter will develop several KV....and wont do the meter any good (or you!)

[kengineering]

Sorry for the missing details. The ballast I encounter most is an electronic (no starters) ballast type capable of lighting between 2 and 4 individual F-17 T8thru F-40 T8 fluroscent tubes. The input is 120V, output is listed as 600V. I am trying to measure output at the socket (inside the display fixture) to quickly determine the cause of the problem when a bulb stops working. Since there are many causes and this puts me in the center of them I could then go toward the bulb or toward the ballast as the root problem. My meter goes to 600v and is of no help. Ken

[The MG Pony]

if it puts out 600 and your meters max is six hundred then of course it wont work. you need a meter capable well over the voltage your measuring. Electronic ballasts need a load to run, slap in a bulb and try a meter rated for 1Kv max and then you aut to get some where, or get a good heavy duty metal oxide resister that matches the filaments ohm rating as a fake load.

Fluorescent lights are deceptively simple looking but there is some complex physics behind them, first it heats the both filaments to warm the gas inside the tube, then kills one while keeping the cathode hot (Some keep both hot) once electron saturation of the gas is complete an arc is formed from the cathode to anode and thats where the ballast does its work is maintaining a steady current through the gas. So needles to say if there is any issue, it WILL be the ballast as the tube its self has very little to go wrong, 2 filaments thats it.

If I where you, Id check to see the sockets are clean and making good contact, then I'd check the wire splices to ensure they where tight and making good contact, if they are, time for new ballast. I used to do work with the school maintenance here and I have seen to many of the things. Save your self the time, just send in the ballast for recycling and toss a new one in providing it isn't a loosened splice or crummy socket.

[chillin out]

I would test it without the tubes connected, but then again I wouldn't really be testing it anyway.

It's quicker to try a new tube than test anything. Most of these 'electronic' ballasts have 2 tubes attached. Make sure both of them work, because if one is faulty then none of them will light.

Chillin