power at fixture, new bulbs--NO LIGHT

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Old 10-29-13, 10:38 AM
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power at fixture, new bulbs--NO LIGHT

I have a row of twin 4' fluorescents that are on two three-way switches. None of the lights came on this morning. This has happened before, but how the problem got fixed is a mystery. So it has happened again and my poking around hasn't helped. Using a tester, I have power at one of the fixtures in the middle of the row(only one I've checked) and for fun I put in new bulbs. If I have power at the actual lamp holder, and new bulbs, shouldn't I have light?

head scratcher for me
 
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Old 10-29-13, 10:52 AM
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If the tester is a non contact tester your reading is meaningless. You need to use a multimeter, preferably analog, a solenoid tester, or a test light. If the wires are daisy chained you need to start checking power at the first light then the light it feeds and so forth. Since none work it is probably the one connected to the switch.
 
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Old 10-29-13, 11:27 AM
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I used a voltage tester, analog. I am going to test voltage before the ballast and compare to voltage at lamp holders. But again, If I have power at the actual lamp holder, and new bulbs, shouldn't I have light?
 

Last edited by Nashkat1; 10-29-13 at 12:08 PM.
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Old 10-29-13, 11:59 AM
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The operation of the ballast is too complex to be checked by a simple voltage check. It is not a simple supplier of voltage. It may supply a momentary high voltage to start the bulb, no good way to check that. Plus depending on the type of ballast it has other functions such as a voltage limiter to control the light after it is started.

Voltage checks are only for supply voltage.
 
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Old 10-29-13, 12:02 PM
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I am going to test voltage before the ballast and compare to voltage at lamp holders
How are you planning to test for power at the tombstones (lampholders)?

If I have power at the actual lamp holder, and new bulbs, shouldn't I have light?
If you have the proper power, if there is a complete circuit, and if the bulbs have been tested in a working fixture and demonstrated to be good, then yes. But if any one of those conditions is not met, then no.
 
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Old 10-29-13, 06:54 PM
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Check your tube pin connections at the sockets. Turn the power off, ensure the tubes are turned in correctly, and give the sockets a little push into the tubes.
Or your 3-ways may not be wired correctly.
 
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