I want to replace the AC ballast in a fluorescent lighting fixture that also has an emergency ballast hooked up in parallel. If I cut the electric power, I believe the battery in the emergency ballast will activate and make at least one lead that is connected to the AC ballast “hot”. Do I have to let the emergency ballast discharge before changing the AC ballast?

lights to wires in parallel not series.

If your shop is in your garage, and it is cold outside, the two-pin fluorescent tubes don't work very well. Garage lighting (fluorescent) should be the HO (high output) type. It operates on the same voltage. The tubes are not interchangeable. You need a HO fixture. If your shop is inside your house, then flickering tubes (assuming that you tried changing them out with new ones) indicate a bad ballast inside the fixture. You can either change out the ballast, or for almost the same price, replace the fixture.

"CFLs" Compact Fluorescent Bulbs (with built in ballast) must be labeled as dimmable to be used on a dimmer circuit.

Traditional fluorescent fixtures must have a dimmable ballast installed inside and can be used with standard fluorescent lamps.

Fluorescent lamps must be sized to match the ballast. CFL's are matched at the factory, but others are not. Older fluorescent lamp fixtures have a ballast inside. A type rating is to operate (2) 48 inch / 40 watt lamps. Newer fluorescent lamps are rated for 32 watts, and these will not work - or will have a greatly reduced life.

If you installed CFL's, the first thing I would do is install regular incandescent lamps and see if it works as expected. If not, something else is wrong - otherwise - make sure you've got the right lamps in the fixture.

If you are sure the ballast is gone, just cut the wire as close as possible to the ballast, throw the old ballast and buy a same wiring ballast, use wiring nuts to connect the wire from the new ballast to the wire from the tomb stone socket. DO NOT TRY TO take the wire out from tomb stone lampholder.

Below link is for your reference.

http://www.bulbspro.com/electrical/sockets/fluorescent-sockets.html

http://www.bulbspro.com/ballasts/ballasts/fluorescent-ballasts.html

Purchase a new one

I like to start by swapping the position of the bulbs. If the one that didn't light, now does, it probably indicates a bad ballast (that long thin black "boxy thing" with wires coming out of it - it may be under a removable metal cover). Next replace the unlit bulb with a new one. If that doesn't light, try swapping the new light to the other position. If you still can't get two bulbs to light, replace both lamps with new ones. A good indication of a bad bulb is one or both blackened ends. The bulbs having two pins on each end have a small filament inside. This blackening is the metal of the filament "boiling off" and depositing on the glass. Eventually the filament gets thin and breaks so it doesn't provide the heat necessary to "prime"" the mercury inside the bulb that conducts electricity and excites the phosphor coating inside the bulb that emits light.If none of this works, most probably the ballast has "gone bad" and it, or the whole fixture, must be replaced, normally by an electrician. This can be done by the home "handyperson." You can cut the wires, remove the old ballast and replace it with a new one, splicing them to those of the same color from the new ballast using small "wire nuts." The one black and one white are the 120 volt power input wires. There are normally a pair of reds, a pair of blues, and a pair of yellows. Any wires of the same color are interchangeable. The blues and reds will go respectively to the bulb's sockets on one end of the fixture; the two yellows go to the opposite fixture end and are connected, in parallel electrically, to the other lamp sockets. If this makes sense, you may attempt to change your own ballast. If not, hire an electrician. Match the specifications for voltage, wattage, and number of bulbs, from your old ballast to the replacement - there are several different important electrical values to match even if the ballast looks physically the same size. Last, always turn off the electricity, and verify that it is safely off using a test light or meter before working on the fixture. Even though the black wire is normally energized and the white has zero volts measured with respect to ground, sometimes their function is reversed by an amateur where the wall switch may disconnect the black wire and make the fixture go off (as it should) yet the white wire remains dangerously energized, which is why you always test both of the wires with the test light or meter with respect to ground before touching any of them. Again, if this is not PERFECTLY clear, hire an electrician. Don't take chances, Electricity KILLS!

Ok - a couple of things, first - when a dimmer is set to minimum; zero to a barely perceptible level of light output is expected. Second, fluorescent lamps have a much shorter range of dimming that the standard incandescent lamps have. It is not unusual for a fluorescent lamp to remain off until the dimmer is at or above the half way point in the dimmer's range. Third, you can not dim a fluorescent lamp or fixture unless the lamp or fixture is specifically labeled as being "dimmable". Use of a dimmer to control brightness of fluorescent lamps and fixtures that do not clearly indicate they are designed for dimming or to control the speed of motors like those in "paddle fan & light fixtures" creates a dangerous fire hazard condition. Most CFL (compact fluorescent lamps) that readily replace the screw-in incandescent type lamps and are clearly labeled as dimmable, can be used with a standard dimmer. The traditional (non-CFL) fluorescent fixtures that have a internally mounted and hard wired internal ballast need a special dimmable ballast to operate.

Good luck!

Power to the ballast is good. The power you checked is known as the primary power. The secondary power from the ballast (transformer), should be around 600 volts. This 600 volts is what vaporizes the gas in the fluorescent lamp. Go to home depot and buy a magnetic field tester (we call it a thumper) It has a shirt pocket clip on it. Do not insert the thumper in the fixture lamp sockets, just put it in front of one of the light fixture sockets. It should beep and the light on the magnetic field tester (thumper) should come on if you have a magnetic field in the light fixture socket. This means that the light fixture ballast secondary is working. No beep and no light from the magnetic field tester (thumper) means your ballast is bad. Ballast are dangerous to replace. Have an electrician replace it. Your life is not worth losing over saving a few dollars.

If this is being used as a socket for a 120-volt lamp (such as a compact fluorescent with self-contained ballast or an incandescent lamp), you wire the black (hot) AC line conductor to the brass-colored screw and the white (neutral) conductor to the silver-colored screw. If the socket is equipped with pigtails instead of screws, use pressure connectors (wirenuts) to connect black to black, white to white.

If you are using HID lamps, you don't wire directly to the AC line. These lamps must be used in a fixture with the correct ballast transformer, capacitor and ignitor (for pulse-start lamps) for the lamp wattage. If you are replacing the socket in such a fixture, follow the wiring of the old one when installing the new socket.

What you do is cut the wires from the old ballast that feed to the fixture end connectors then 'wire nut' the new ballast wires to the old wires.

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