Electrical fires have increased significantly. According to İstanbul Fire Brigade's 2021 figures, 5,105fires were caused by electrical faults. Increased demand overloading older installations is a major factor, while failures to follow standards and regulations also create problems in newly installed systems.
Fuses and circuit breakers protect cables and conductors against overcurrent. Their effectiveness has been demonstrated over many years, but they are not designed to protect against very small arc currents. Arc types are often confused; this article explains some of the differences.
A parallel arc occurs between phase and neutral; in other words, it is a short-circuit arc. Circuit breakers are used for protection against parallel arcs and must be selected to suit the system load.
An earth arc is an arc from a phase conductor to earth. Residual current devices are used to protect against this type of earth fault.
A series arc occurs along a current-carrying conductor and can have several causes, requiring the appropriate protective device. Residual current devices, commonly called leakage-current relays, are sometimes described as fire-protection relays. That description does not accurately reflect their primary purpose.
Different fault types require different protective devices.
Miniature Circuit Breakers (MCBs): Used for overcurrent protection in short-circuit faults, including parallel arcs.
Residual Current Devices (RCDs): Used for earth-fault protection.
Arc Fault Detection Devices (AFDDs): Used to detect series arc faults.
Arc fault detection devices can help prevent losses far greater than their installation cost. Seasonal influences and additional loads introduced after installation can increase fire risk where the protective devices for cables and conductors remain unchanged and the installation is not reassessed.
Periodic thermal imaging of electrical panels, equipment and installations can identify overheating and support fire-risk prevention. Equipment running above normal temperatures can then be examined or replaced before damage occurs.
Thermal imaging while the installation operates at full load is particularly valuable for identifying potential fire risks. Measurements taken without a representative operating load may fail to reveal the overheating conditions being investigated.
In addition to thermal imaging of panels, periodic insulation tests should be performed. They can reveal faults at points that cannot be seen directly or examined with a thermal camera.