Testing Fluorescent Ballasts

[Anonymous-0]

How does a person test a ballast?

Thanks,
Glenn F.

 

[snoop-nc]

Glen: I am pretty sure those ballast are "temperature" sensitive. You might be using a "hot" ballast in a "cold" location. How to test???...maybe electrical supply house can shed some lite (bad pun).

Be safe...electricity bites w/o warning

 

[Dick L]

Test with an ohm meter. check both wires to the case one at a time to see if it is shorted out. Checking across the two wires to see if it is open.
open or shorted would mean they are bad.

 

[Bob]

What's to test?

If a fixture doesn't work with new bulbs, and has power to it ballast is BAD.

 

[KIDbob]

I try new bulbs, if they don't work I replace the ballast. Be sure the old ballast has cooled enough to reset the internal thermal breaker.
The last time I got the electronc instead of the magnetic, the bulbs glow much briter and I think on less electricity, but you have to rewire the fixture to the diagram on the ballast. The ballasts I got work on anything from 110 volts to 277 volts, just get the ones rated for the bulbs you are using.

 

[Jon Hagen]

If it is a new installation where the bulbs do not light or are slow to light, check the wiring polarity.
I wired a pair of cheap China made 4 ft florescents over a temporary work bench, I powered them through a polarized 3 pin grounding plug /extension cord, so I could just plug them into a work bench 120V fixture. Well they were really slow to light and would not come on when it was a little cool.
I tried other known good bulbs with no better results while cussing out cheap China made junk fixtures.
As a last resort, I opened the fixture and checked my wiring of the plug in power cord.
sure enough, I had the white fixture wire connected to the "hot" lead in the un color coded power cord and the un color coded nuetral hooked to the black fixture lead. But then a frorescent fixture does not care about wiring polarity, does it ??

Yep, switched those wires and the fixtures worked great. They DO care if the hot lead connects to the ballast first instead of the bulb.
Yep, then I knew who the dumb bass was, and it wasn't some factory worker in China LOL ;-)

 

[barn E]

Be careful is right. This old electrician knows 2 guys fried by fluorescent ballasts. One was one was on job with me. He was master, always wore gloves. We were told to do all work HOT not to interfere with production. He forgot to put on gloves one time,all she wrote. 4 footers used to put out 150volts to sockets. 8 footers up to 550 volts. Other guy grabbed a light with defective ballast that was not grounded and other hand on grounded metal cage or cribbing. Years ago they made little socket things to plug into lamp socket for testing. Never used them. Lamps have filament on each end that is fired by ballast, then high voltage arcs across end to end through gas inside. Would you say 3 circuits in ballast that must all work or no good lighting. Dave

 

[Anonymous-0]

There is a related issue with some ballasts/fixtures. Reliable initial startup of the lamps can depend upon the metal fixture being properly grounded. The fixture relies upon capacitive coupling between the tube and the metal back plate during the initial "strike". If the fixture is not grounded the lamps can act flaky, refusing to start or "magically" starting only when you touch the tube.