With most electrical problems determining the fault requires experience, training and the ability to use electrical testers.
There can be a variety of reasons for a electrical fault, some which can be extremely dangerous, that can result in electrocution, being shocked, and fire. Fire from an electrical fault is the single biggest cause for a fire in a premises.
All electrical work done must conform to SANS10142, and be undertaken by a qualified and registered electrician.
One of the biggest causes of electrical faults are:
Cables (Conductors) being overloaded and not proper circuit breaker protection; remember the circuit breaker protects the conductor.
- Cables burning back from the connection, due to aging and stress of the conductor.
- Loose connections, normally at the circuit breaker/switch disconnecter; the terminations at the switch socket, lighting connection, and where joints have been made.
Alot of the above cannot be seen by the eye, unless covers are taken off; circuit is switched off and an insulation test is done between phases, phase to neutral and phase to earth.
Thermal Infra Red Surveys can prevent the cable faults, the breaking down of electro-mechanical devices.
Earth Leakage Units can also be a cause of an electrical fault.
- If the Earth Leakage is faulty; this can quickly be identified through an earth leakage unit tester; which will also show if power is on and the polarity is correct.
A manual test of the test button, which should be done by the tenant / owner on a regular basis will also determine is the unit is faulty. An earth leakage unit monitors any leakage problems, and will should trip is 30mA or more current is drawn to earth.
A earth leakage unit will also trip if there is a neutral fault.
Circuits that are installed on earth leakage will have a separate "Earth Leakage" Neutral Bar.
In some installations I have come across, the whole installation was been wired through the earth leakage unit; and if there is a neutral down to earth, for example on an external light fitting, the whole installation will trip and be with out power.
Cable Faults: Main Supply Cables that either have been mechanically damaged, or over the years have been stressing where the cable bending radius was not followed, and also underrated cables that are not protected by the correctly rated circuit breaker.
Remember, electricity can kill; always call a qualified electrician if you want any electrical installations or maintenance done.
Multicore PVC insulated cables, unarmoured, with or without protective conductor – Current carrying capacity copper conductors (Example only). This table shows just how important selecting the correct cable, taking into account what load / current may be drawn.