Testing for bad ballast

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iwire64

Member
Location
US
Will a voltage meter help me determine if a fluorescent ballast is bad? How di I test without changing lamps?

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JFletcher

Senior Member
Location
Williamsburg, VA
Changing lamps for known good units is still the best way imo. I've never used a DMM or voltmeter to test them. They either work fine with new, compatible bulbs or they dont.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
To evaluate the effectiveness of the ballast you need to know both the open circuit voltage (supply as modified by turns ratio or switching) and the voltage under load.
To measure the latter you need a known good load, so you might as well start by changing the lamp.
And then you usually do not need to measure the voltage!
:)

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tom baker

First Chief Moderator
Staff member
Its either the ballast or the lamps. Companies (Greenlee) make a lamp tester which has an extendable antenna to test the lamps.
Here where I work (city) with a lot of buildings, by the time you drag out a ladder, open the cover, at that point if its not the lamps its the ballast. change it and the lamps and you are done
 

kwired

Electron manager
Location
NE Nebraska
I agree with others if you are wanting to test output leads.

One thing you can do with meter is verify there is input voltage.
 

JFletcher

Senior Member
Location
Williamsburg, VA
Its either the ballast or the lamps. Companies (Greenlee) make a lamp tester which has an extendable antenna to test the lamps.
Here where I work (city) with a lot of buildings, by the time you drag out a ladder, open the cover, at that point if its not the lamps its the ballast. change it and the lamps and you are done

It could be the tombstones or a failed splice or a loose lamp, but yeah, most times it's bulbs or ballast.
 
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