Because they are not easy to inspect, damaged pendant lamp holders often go unnoticed, so check their condition from time to time and replace any that look suspect before they become dangerous

Pendant lamp holders, which hang on flex from ceiling, are in a stream of hot air rising from the bulb, and in time this can make plastic holders brittle and more easily cracked or broken. On a metal lamp holder, the earth wire can become detached or corroded so that the fitting is no longer safer.

Types of lamp holder
1. Plastic Lamp holder are the most common. These have a threaded skirt that screws on to the actual holder, the part that takes the bulb, and some versions have an extended skirt for fitting in bathrooms. You should fit heat resistant plastic holders if you use a close fitting or badly ventilated shade. Plastic holders are designed to take two core flex only. Never fit one on a three-core flex, as there is no place to attach the earth wire.
2. Metal lamp holders are similar in their construction, but they must be wired with three core flex so that they can be connected to earth. Never fit a metal lampholder in a bathroom, and never attached one to a two core flex, which has no earth.