"goodfella" wrote in message
ups.com...
I have an "U" shaped fluorescent light in my kitchen that may or may
not come on at the first flip of the switch. If you rapidly flip the
switch several times, then it will come on and stay on. It is the
only light on the circuit. I hadn't changed a thing on the circuit, so
it shouldn't be something I did. We changed the bulb and changed the
switch but it still did the same thing. I have another fluorescent
light exactly the same next to it (two lights in the kitchen) and it
works fine. Would the ballast be bad?


Thanks

For a replacement ballast, look on the label of the ballast that's in your
fixture now. You will see the types of lamps that will work with that
ballast. If you don't see your U-shaped lamp, that's O.K. Probably the
U-Lamp is electrically like an F40T12/RS or some other type for which there
is a linear equivalent. Then go to the store and buy a ballast that
operates the same types of lamps.

There are several things that could be affecting the starting of your
U-Lamp. Fortunately, they are all fairly simple to check.

- First, take out the lamp and clean it carefully with Windex or dish
detergent. Rinse and dry thoroughly. (When a film of dirt builds up on the
surface of these lamps, they become a bit harder to start.)
- Second, take the lamp out of the socket and then replace it again so the
pins scrape the socket contacts.
- Third, check the metal part of the fixture to be sure it's grounded. The
ground (bare or green) wire of the incoming cable should be connected to the
metal of the fixture and/or the metal case of the ballast. You can also
check grounding with an ohm meter.
- Fourth, check to see whether the "hot": and "neutral" wire are reversed.
This is unlikely since the lamp has been O.K.; but the lamp will have
trouble starting if those wires are reversed. The black wire of the
incoming cable should go to the black wire of the ballast and the white wire
should go to the white wire of the ballast.

The basic problem is that older ballasts are designed to provide just enough
voltage to start the lamp and very little more. And, a grounded fixture is
part of the starting circuit since a grounded metal strip must be within
3/4 in. of the lamp. So, as the lamp ages and the starting voltage
requirement goes up, poor grounding, reversed leads, dirty lamp may all
conspire to make the lamp harder to start.

When you flip the switch, you are forcing the ballast to hit the lamp with a
pulse of voltage. When you hit the switch just at the right point in the 60
Hz cycle, enough voltage is generated to start the lamp; but that may take
several tries as you have found.

If you decide to change the ballast, go with an electronic type. They put
out plenty of starting voltage.

TKM