Electrical connectors are the simplest type of component used in electrical engineering systems. Their very simplicity can make them liable to be neglected and their importance overlooked. The electrical connector connects electrical conductors and must achieve very low electrical contact resistance. This is achieved by the contact force (compression) within the connection and applied by the terminal screw. The ability for the electrical connector to maintain contact force, and therefore low contact resistance is essential and fundamental for the safe performance of the connector.
Each year there are many incidents, recorded by Fire & Rescue Services, of fires in homes and businesses caused by high contact resistance /high-temperature electrical connections. Categorising these incidents has highlighted that this risk is especially common in electrical supply intake equipment (main intake fuse, electricity meter & consumer unit connections).
If a high resistance/temperature electrical connection begins to develop, it may steadily get worse without anyone becoming aware of it. High resistance electrical connections can be initiated by simple local environment changes i.e. through temperature fluctuations (including cyclic heating from electrical loading) or vibration and even if the connection cables have been moved or disturbed slightly. They can also be caused by sub-standard installation or maintenance works. A high resistance/temperature electrical connection can take weeks, months or even years to develop. Eventually, the connection may become hot enough to ignite the insulating materials around it, or eject sparks through electrical arcing to ignite combustibles in the vicinity. The ensuing fire can then spread destroying property, life and business.
Developing high resistance/temperature electrical connections cannot be easily detected, without the use of specialist equipment. It is therefore easy to understand how, once developed, they can deteriorate and cause fire.