Older homes come with their own charms and dangers. As electrical systems have progressed over the past few decades, some older homes don’t comply with new regulations. This doesn’t mean that you are necessarily violating the electrical code. But, in older homes, it can be easier to violate codes because information isn’t as readily accessible. For example, older lighting fixtures sometimes don’t have the maximum wattage imprinted on them. Without this information, homeowners are more likely to put an improper bulb that could result in an electrical code violation.
Using the wrong bulb can be dangerous or not. The danger occurs when a bulb with a higher wattage is put into a light fixture intended for lower wattage. We call this “overlamping.” It means that the bulbs is trying to draw more power than the light fixture is capable of handling. The bulb is likely to overheat. There is no cutoff in a light fixture, so it will continue to overheat, melting insulation on wires around the socket. Removing an overlamped bulb can become dangerous because the exposed wires are at a higher risk of arching.
However, some simple guidelines will keep those “mystery” light fixture with no marked wattage working safely. One baseline rule is to not use more than a 60-watt bulb. Older light fixtures are from an era of lower power consumption. 60-watt bulbs should be the maximum that you insert into an old light fixture.
Another option is to use new high efficiency bulbs. LED and CFLs typically require less power to work. A 60-watt equivalent LED bulb may only use 20 watts. The same rules apply to all bulbs though. To avoid overlamping, it’s best to match the wattage of the light fixture to the wattage of the bulb. Even LEDs can overheat if overlamped.
If you are concerned that a light fixture in your house may have been overlamped, it’s best to call a professional. The damage caused by overlamping is not limited to the bulb. Exposed wires can make the light fixture dangerous. Professionals will identify any wiring damage quickly. They can also conduct a lighting evaluation, which confirms that you are correctly pairing bulbs and lighting fixtures. A lighting evaluation can also help identify any other places in the house that may have been overlamped in the past.
If you see a light overheating and flickering in your old home, it’s possible that it has overlamped. The best path forward is to call a professional for a wiring inspection. Once the fixture is deemed safe or is fixed, you can insert the correct wattage bulb for safe and consistent lighting.