These operate at elv (extra low voltages) between 3 and 12 V. The single bell, buzzer and many models of chimes are powered by dry batteries but the more powerful chimes and intricate bell systems have to operate from mains transformers. Usually a transformer is preferable for any bell or chimes. Where an illuminated bell push is used a mains transformer is essential as the lamp of the push would exhaust a battery in a day or so. Read the rest of this entry »
Socket-outlets situated off the main route of the cable do not have to be connected to the actual ring cable. Instead they are usually supplied from spur cables branching off the ring. These spurs are wired in the same size cable as that used for the ring.
Fixed appliances which may be connected to a ring circuit include skirting heaters, wall heaters, small water heaters and any non-portable electrical appliances having individual loadings of not more than 3000 W(13 A approx.). Read the rest of this entry »
Of the two principal types of cooker control unit, the type incorporating a kettle socket-outlet is the more popular. Since, however, it is important that the kettle is not used on the cooker hob where its flex would trail over a switched-on boiling plate it is better to have the unit without a socket where it has to be fixed immediately above the cooker. Read the rest of this entry »
Small table cookers and other portable appliances having individual loadings not in excess of 3 kW are run off 13 A fused plugs and socket-outlets. They require no special wiring though extra socket-outlets may be needed in the kitchen when additional electrical cooking appliances are bought. These additional socket-outlets may be served from the ring circuit and spurs.
Family-size cookers, whether free-standing or built-in split-level, need an exclusive circuit from a fuseway of appropriate current rating. Read the rest of this entry »
Where the white meter tariff is in operation it can be an advantage to heat the full contents of a tank overnight when the cheaper rate for electricity is in force and switch on the short element wizen additional hot water is needed.
This normally requires two circuits for the immersion heater installation. One circuit is used for the night rate supply, when time controlled in conjunction with night storage heaters, this supplying the long element of a dual immersion heater or the lower immersion heater of a two- immersion heater arrangement. Read the rest of this entry »
Electric heating of water can be carried out in a variety of ways. These include small capacity heaters fitted above the sink, instantaneous sink heaters or immersion heaters in the hot water tank.
Small storage water heaters fitted over the sink or washbasin having capacities of up to about 3 gallons and electrical loadings of 1 to 3 kW are usually supplied from the ring circuit by means of a spur. Except in a bathroom, the outlet can be a fused plug and switched socket-outlet, preferably with neon indicator. Read the rest of this entry »
Storage heaters require a separate circuit for each heater. This is because, unlike direct acting heaters which are switched on and off as required, storage heaters are all switched on together during the 8-hour period. They cannot therefore be supplied from a ring circuit which is based on diversity of use of various appliances; each heater must have its own circuit. 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 »
Portable electric heaters and many fixed electric heaters are controlled by a switch or switches mounted on the frame of the heater. In addition, the heater is switched at a switched socket-outlet or switched fused connection unit or is connected to a non-switched socket-outlet which means pulling out the plug to switch off the heater.
Wall panel heaters, oil filled radiators, convectors and other heaters operating at ‘black heat’ have an integral thermostat which is set to the required room temperature. Read the rest of this entry »
Formerly imperial ratings were used for fuses and circuit breakers, but the international Renard ratings have now been added and will supersede them.
Fuse manufacturers are still using the imperial sizes while circuit breaker manufacturers have mostly changed to the new ratings. An equivalence chart is shown above.
The miniature circuit breaker (MCB) is now widely used and overcomes all the problems associated with ordinary fuses. It is a small, sophisticated unit affording a much higher level of protection than an ordinary fuse. It is tamper-proof and the unit involved is easily identified when one has tripped (the switch moves to the ‘off’ position). Most importantly, MCBs cannot be reset if the fault still exists; this eliminates the foolish and highly dangerous practice of putting in the wrong fuse wire or cartridge just to get things ‘conveniently’ working again for the time being. Read the rest of this entry »
