Lighting Problems

San Jose Electrician on Lighting Problems

Lights Not Turning On

Lights don’t turn on for six basic reasons:

1. The bulb is bad. This is more common than one might think. Try replacing a questionable light bulb with a new one. If that doesn’t work, before giving up, try using a bulb from another light fixture that you KNOW is working.

2. The switch to the light is bad. The switch will need to be replaced.

3. The light fixture is broken. Usually it is easiest and least expensive to simply replace the fixture. However, many light fixtures can be repaired if it is desired.

4. No power. Please go to the Power Problems section.

5. The time clock for the light is not set for the correct time or is broken. Re-set the time or replace the broken time clock.

6. If the light fixture is activated by a photo-cell, the photo-cell is out of adjustment or broken. Adjust or replace the photo-cell.

7. Fluorescent, Mercury-Vapor, or High-Pressure-Sodium Lights. These kinds of light fixtures all use an electrical ballast to energize their special light bulbs. If the light is humming loudly or has an “electrical odor,” or if the light just doesn’t turn on, the ballast may need to be replaced.

Lights Not Turning Off

1. The switch to the light fixture is broken. Replace the switch.

2. The time clock for the light is broken or out of adjustment. Set the time clock to the right time. If it won’t stay adjusted, replace the time clock.

3. If the light fixture is activated by a photo-cell, the photo-cell is either out of adjustment or broken. Adjust or replace the photo-cell.

Lights Blinking On And Off

There are two main reasons for lights blinking on and off:

1. A photo-cell is out of adjustment. Adjust the photo-cell.

2. Some light fixtures that are recessed into the ceiling have a built-in thermal protector that automatically shuts off the light when the fixture gets too hot. Use a lower wattage bulb for a lower temperature.

Flickering Fluorescent Lights

There are three reasons fluorescent lights flicker:

1. For a few moments when they first turn on, the bulbs will flicker until they warm up. You will notice this more on colder days. Just wait a few moments for the bulbs to warm up.

2. The fluorescent bulbs are old. Replace them.

3. The fluorescent ballast is old. Replace it.

Bulbs Burning Out Too Quickly

Here are the three reasons bulbs can burn out quickly:

1. The wattage of the bulb is too high. This is very common. Most light fixtures with glass covers have a maximum rating of 60 watts per bulb. It is very common for people to put in 75 watt or even 100 watt bulbs. The result is bulbs burning out much too quickly. Use the correct wattage bulbs in all your light fixtures.

2. Poor-quality lights bulbs. Use only major-brand light bulbs.

3. Mysterious light fixture problems. It’s mysterious because the light fixture LOOKS perfectly fine, and even electricians can’t find anything wrong with it. Nevertheless, after checking #1 and #2 above, if the bulbs keep burning out…replace the light fixture.

Humming Lights

Humming lights can be caused by:

1. A bad ballast or bad transformer. Replace the ballast or transformer.

2. A conflict between a low-voltage dimmer and the low-voltage light fixture it controls. This is a tough one, but sometimes experimenting with different dimmers will lead you to one that doesn’t make the low-voltage light transformer hum.

Lights Dimming

Lights will sometimes dim for a few seconds and then come back to complete brightness again. This can happen when a light is connected to the same wires that provide power to an appliance that takes a lot of power, like a refrigerator, a microwave oven, or an air conditioner. The reason the light dims for a few seconds is that the appliance is using a lot of power when it first starts up. After the appliance is running for a few seconds, it will use less power, and the light will return to normal again. If you have central air-conditioning, the lights may dim each time the air conditioning comes on.

You will usually notice this dimming more at night (for obvious reasons!), but you might also notice it in the daytime. If this dimming bothers you, you can handle the problem by having an electrician add another circuit specifically for the appliance that is causing the dimming problem.

NOTE: If you haven’t changed anything electrical in your home or office, and you suddenly start to have dimming problems or power fluctuations, then you probably have a loose wire somewhere. You should contact an electrician skilled in troubleshooting to find and correct this problem.

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