A radial power circuit is the name given to a circuit supplying a number of 13 A socket-outlets and fixed appliances using one cable which is not wired in the form of a ring but terminates at the last outlet.
The permitted number of socket-outlets (and fixed appliances) depends on the current rating of the circuit which can be either 20 A, wired in 2.5 mm2 cable, or 30 A wired in 4 mm2 cable. The number of socket-outlets and fixed appliances which can be served by a 20 A radial circuit depends also on the location of the circuit and whether the outlets are confined to one room. Read the rest of this entry »
Joint boxes are usually circular and for part of the circuit wiring. They are fix permanently to the house structure are used principally in lighting circuits. Join boxes are available in 4- 5- and 6-terminal versions.
A 3-terminal joint box of 30 A current rating is used for ring circuits to connect spur cables to the ring cable, as shown the illustration. Read the rest of this entry »
A fused clock connector is a small non- switched fused outlet designed expressly for supplying a mains electric clock.
The unit is in two sections: a fixed base which is connected to the fixed circuit wiring, and another section in.the form of a flat pin plug which plugs into sockets in the base. The plug section carries the flex of the clock and contains the fuse. The plug is secured in the base by a retaining screw. This prevents the plug being pulled out accidentally and stopping the clock. Read the rest of this entry »
Problems with electrical appliances may not always result from a failure of the equipment itself. They can be caused by the failure of electrical supply to the appliance via the socket. A three-pin socket must have a live supply, a neutral return and a sound earth path. When a plug from an appliance is inserted, firm contact must be made at all three points. If the live or neutral pins of the plug or connection point within the socket fail to make adequate contact or are free to move, localized heating will occur within the socket. Typical signs of this problem are listed below.
There are various reasons for such problems. They may be caused by one or a combination of any of those listed here. Read the rest of this entry »
