Overlamping is when a lamp-holder socket has a bulb with a higher wattage than the socket is designed for. Not every lamp-holder socket in your home is rated for the commonly used 100-watt incandescent light bulbs. This is a code violation and a highly dangerous fire hazard.
For instance, if you connect a100-watt light bulb into a 75-watt lamp-holder socket, the intense heat coming from the bulb can melt or scorch the socket, potentially exposing the electrical wires underneath. This is a possible fire hazard as it increases the risk of arcing. Arcing is when sparks jump through the air from one wire to another, and research has shown that it is one of the most common causes of electrical fires.
The United States system of safety standards requires that electrical equipment be listed. Listing is a tool used to facilitate acceptance of electrical equipment. Most lamp holders are listed up to a particular wattage depending on the type of fixture used. This rating is derived from things such as the types of materials used in the construction of the fitting as well as where it will be placed. This causes varying levels of wattage, although most common lamp holder sockets are rated 75 watt.
You may find that some sockets in and around your home are listed at 40 watts or even 25 watts. An electrician can test the sockets in your home and confirm the maximum wattage for each one.
Most experts agree that using a bulb with a maximum wattage of 75 watts is the safest option, but you can always ask your electrician for help to be certain. Modern high-efficiency lamps are much safer because the majority do not exceed 75 watts of energy consumption. For older and unmarked fixtures, it is best to use a 60-watt bulb instead.
If you notice a lamp-holder socket in or around your home that looks as if it is scorched or melted, it is best to ask a professional for help before using it. If you would rather not seek an electrician’s assistance and choose to do the repairs yourself, ensure that you have switched off the electricity at the mains and that you have the correct tools for the job.