98 Wiring Systems and Fault Finding For Installation Electricians If the connections to any winding are reversed, the magnet fields will work against each other and a serious overload will occur, especially when the starter changes the motor windings to the delta configuration. For example, never allow A2 to be connected to B2 and A1 to C1.
CONCLUSION AND A CAUTIONARY TALE Finally, it must be reiterated that successful and efficient fault finding has its basis in experience. However, for the beginner, use a logical and methodical approach, ask questions of the customer or client, and use some common sense. This in itself will often provide the clues for the diagnosis of system failure. Once upon a time there was a young electrical apprentice (who shall remain nameless), who was doing a little wiring job (not private, of course). The customer asked the apprentice, while he was there, to investigate whether a cracked socket needed replacing. Of course he agreed to (thinking: ‘extras!’), and proceeded to undo the socket without isolating. There was a pop and a flash and the ring circuit fuse operated. ‘Silly me,’ he thought, ‘I’ll just repair the fuse, I must have shorted something out in the socket.’ ‘Hold on,’ thought he, ‘do this properly: never replace a fuse until the circuit has been checked first.’ An insulation resistance test seemed to be the order of the day, so naturally all appliances were removed from the ring and the test applied. It showed a line neutral short circuit. ‘Oh! bother ’ (or some such expletive), he muttered, ‘Where do I start?’ Unfortunately the ring circuit was wired in the form of junction boxes in the upstairs floor void with single drops down to each socket. Splitting the ring meant gaining access to those JBs. Needless to say there were fitted carpets and tongued and grooved floorboards, and no access traps.
