Thursday, January 28, 2010

The Easy Lamp Repairs


You turn on your trusty reading lamp and—nothing. Chances are it’s the light bulb. Remove the old bulb, screw in a new one, and you should be ready to go. If not, you’ll have to inspect further. Your problem could be …

➤ The power supply.
➤ The receptacle.
➤ The contact tab at the bottom of the light socket.
➤ The light socket.
➤ The cord or plug.

The power supply and the receptacle are easy enough to check. A voltage tester will tell you whether the receptacle is hot, and a quick trip to your fuse box or service panel will tell you whether the problem is originating there. If a breaker has tripped or a fuse has gone out, you need to discover the cause before you can consider the problem solved.
The contact tab at the bottom of the socket is the same one referred to previously in this chapter in the “Inspect First” section. Simply unplug the lamp and use a small screwdriver to pull up slightly on the tab. If the bulb still doesn’t work, you’ll have to look at your cord and plug more closely.

The Pieces Inside Fluorescent Fixtures


All fluorescent fixtures have the following major components:
  • Ballast
  • Sockets
  • Lamps (a.k.a. light bulbs or tubes) The ballast is like a small transformer inside the fixture.
It has two major jobs:
  • First, it provides the spark that sets off the gas within the tube, making that gas fluoresce. This requires higher voltage.
  • Then, the transformer reduces the voltage to the (very low) level necessary to sustain lighting.
There are three main types of ballasts or fluorescent circuits: preheat, rapid start, and instant start. (The type is identified on the ballast casing.)
Preheat technology dates back to the original fluorescent fixtures, and it is used today mostly for certain low-wattage fixtures such as compact fluorescent fixtures. This type of circuit uses a starter.
Rapid starts are the most frequently used ballasts today. They maintain a continuous low-wattage circuit to the lamp’s filaments so they start up faster (in less than a second). This style of ballast also comes in a version that allows dimming. An instant-start ballast, as the name implies, ignites the gas in the lamp instantly. It supplies a higher starting voltage than the other types of ballasts, and like the rapidstart variety, it requires no separate starter. The drawback to this voltage boost is that it requires a special lamp. The lamp also will have a shorter life than those used for rapid-start circuits. One way you can distinguish between the lamps is by the number of pins on the ends of the lamp. (These pins insert into the fixture’s sockets or tubeholders.) Rapid-start lamps are bi-pin (they have two pins); most, but not all, instantstart versions have only one.

Try a New Style


Styles and fashions change, a fact that’s certainly not lost on America’s retailers. The dim ceiling fixtures with the square-shaped glass domes from the 1950s and 1960s just don’t cut it any more, unless you’re into retro-hip lifestyles complete with hula hoops and strange-looking dinette sets. The array of fixture choices today is astounding. Just about any period of fixture can be matched, or a completely updated style can be installed. The only limits are your imagination and your checkbook. Some fixtures can greatly increase the amount of lighting in a room. A single overhead fixture in a long hallway, for example, might be replaced with track lighting running the length of the hallway, turning it into a great space to display paintings or photographs. As always, make sure your circuit can support the increased current demand should you replace a fixture with one of a higher wattage rating. There’s no need to limit yourself to using incandescent fixtures to replace your existing ones. Fluorescent fixtures, especially compact models, should be considered as well.

Thursday, December 31, 2009

Installing a Fixture Box


A self-supporting retrofit box can be installed in an existing ceiling or wall if your light fixture doesn’t have a box. This regularly will be the case with very old wiring or poorly done additions to your electrical system. You’d be surprised how many old incandescent fixtures are attached directly to plaster lath instead of to any kind of box. Retrofit boxes come in two flavors: metal and plastic. Each is designed to fit snugly against either plaster or drywall by using adjustable ears and brackets that expand and/or tighten against the wall. A plastic box has an attached, U-shaped bracket that tightens like a toggle bolt as its attachment screw is tightened. A metal retrofit box comes with brackets or supports (known as “Madison Holdits” and sometimes as “battleships”) that fit between the box and the wall. As they are pulled out, they firm up the fit of the box. The arms of the supports are then bent over the edge of the box, tucked inside, and pinched tightly with pliers.
Another version of a metal retrofit box features a screw-operated support on each side of the box. As the screws are tightened, the metal support wedges the box in tightly against the plaster or drywall. A retrofit plastic box has plastic or metal internal cable clamps that help secure the cables to the box should it ever slip from the opening. Metal boxes are a bit trickier to use if you’re unfamiliar with them, so consider using plastic retrofit boxes for your work.

Time to Replace


Installing new fixtures is a doable homeowner project. It’s easier to do with modern wiring and boxes, but it still can be done with older types of wire as well. To replace a fixture, follow all safety precautions, read the instructions and diagrams that come with the fixture, and …
  1. Turn the power off and test to make sure it’s off.
  2. Follow the preceding steps for testing the fixture’s socket to remove the fixture and undo the wire connections.
  3. If the fixture does not have an electrical box, install .
  4. Install the mounting strap that comes with your new fixture to the box. (The strap, also called a mounting yoke, has predrilled holes set to the dimensions of the fixture.)
  5. Connect the black wire and the white wire from the fixture to their counterparts in the circuit wires.
  6. Connect the grounding wire to the grounding screw on the mounting strap and to the grounding conductor that might come attached to the fixture.
  7. Install a light bulb, turn on the power, and test the fixture. After the test, turn off the power and remove the bulb.
  8. Attach the fixture with its mounting screws to the mounting strap.
  9. Install the light bulb and the globe.

Inspect First


There are two main reasons for replacing a light fixture:
  • It isn’t working, and you believe it is somehow broken.
  • You want to install an updated style or a fixture that will offer more light.
You should do a number of checks before pronouncing a light fixture broken or beyond repair. You already know about checking the switch and the fixture itself for power. In addition, you should look at the following:
  • The lamp (light bulb)
  • The socket
  • The wire connections inside the box
Checking the light bulb is the obvious first course of action—replacing the bulb with one that’s working. If it got jostled around in a storage drawer or even on the way home from the hardware store, there’s always a chance a new bulb isn’t working, so check it in a fixture or lamp you know is working. The next thing to check is the socket. At the bottom of the socket is a small metal tab that makes contact with the bottom of the lamp. Turn the power off and check with your voltage tester by placing one probe on the metal tab and one on the inside of the metal socket. The bulb should not glow. If it does, the power is still on, and you need to shut off the correct circuit. With the correct circuit shut off, test the fixture again with your voltage tester. With the power off, pull the end of the tab up a little bit using the end of a screwdriver. Screw in the lamp, turn on the power, and try the fixture again. These tabs sometimes become depressed or flattened out and don’t form a tight contact with the lamp. Why would the contact suddenly be broken? All it takes is a slight vibration in the fixture from, say, a large truck passing by. If a light bulb that you know is good doesn’t work, you have a problem with the socket. Remove the fixture to test the socket by following these steps:
  1. With all glass globes, lampshades, and light bulbs removed, unscrew the fixture from the box by turning the mounting screws counterclockwise.
  2. Carefully pull down the fixture and let it rest on top of the ladder. This is critical if it’s a heavy fixture.
  3. Disconnect the wires from the terminal screws and take down the fixture.
  4. Attach the continuity tester’s clip to the hot wire terminal screw, and place the probe against the metal tab in the socket. If the tester does not glow, the socket needs to be replaced.
  5. Attach the continuity tester’s clip to the neutral terminal and the probe to the threaded portion of the socket. Again, if the tester’s bulb does not glow, the socket needs replacement.
Some sockets are permanently attached to the fixture, in which case the entire fixture must be replaced. Others are attached to the fixture with screws and can be removed and replaced. Take your old socket to the hardware, lighting, or electrical-supply store and purchase an identical replacement.
The same vibrations also can cause the wire connections to come loose just enough to lose contact with the fixture.

Monday, November 30, 2009

Understanding Light Fixture

Changing a light fixture can be more involved than simply replacing a switch or a receptacle. Switches and receptacles almost always are housed in electrical boxes, but this isn’t always true for light fixtures. If the system is old or has been hacked at enough, you can disassemble an old ceiling light only to find a couple of wires dangling through the plaster without the hint of a box. As you should know by now, this is a dangerous situation because all wire connections must take place within a box. You might feel like cheating by continuing the status quo, but don’t. You’ll need to install a new box (unless one’s already there).
Lights usually get replaced because tastes change. Old fixtures don’t often wear out, since they have no moving parts (unlike a switch). Historic or not, the original hanging lights in your Craftsman home might be ugly to your eyes, or you might want to replace more modern fixtures with replication period fixtures to restore your home closer to its original condition.
The usual safety precautions apply to replacing fixtures that apply to any other electrical work—turning the power off is number one—but now you’ll sometimes be working off a ladder. For that matter, two of you might be working off two ladders if you have to remove an especially heavy or delicate fixture such as a chandelier. One thing is for certain: With the huge selection of new fixtures to choose from, you’re bound to find a replacement that will dress up any room in your house.