Electrical Installation : 04 September 2020
The primary role of an electrician is the installation of electrical circuits and applications. In order to install any type of application, however, it is vital that from the start of your career you are able to put together basic circuitry.
The load refers to the item that requires the supply in order to function. For example, this might mean the lights in a circuit, a heater, a motor to drive a pump or any item of equipment (or combinations of these) that require an electrical supply in order for them to work. Electrical loads are rated in watts or kilowatts (W and kW). The size of the load is generally stamped on the equipment or marked on a nameplate. This can contain the: rating in watts supply voltage ● ● frequency of the supply full load current. ● ● If this information is not available on a nameplate, then it would be necessary to refer to the manufacturer’s literature to establish the requirements of the load.
Wiring using multicore/composite cables This type of cable is normally a sheathed multicore twin and earth or three cores and earth (two-way and intermediate circuits only) (Ref. 6242Y and 6243Y respectively). A ‘loop in’ or ‘joint box’ method may be employed with this type of installation. In many instances a loop-in system is specified as there are no joint boxes installed and all terminations are readily accessible at the switches and ceiling roses. With a joint box system normally only one cable is run to each wiring outlet. Where such joint boxes are installed beneath floors, they should be accessible by leaving a screwed trap in the floorboard directly above the joint box. All conductors should be correctly colour identified.
On a composite cable installation, where the conductors other than brown are used as a phase conductor, they should be fitted with a brown sleeve at their terminations. All conductors must be contained within a non-combustible enclosure at wiring outlets (i.e. the sheathing of the cable must be taken into the wiring accessory). Throughout the lighting installation a circuit protective conductor (cpc) must be installed and terminated at a suitable earthing terminal in the accessory/box. Where an earthing terminal may not be fitted in a PVC switch pattress, the cpc may be terminated in a connector. Where the sheathing is removed from a composite cable the cpc must be fitted with an insulating sleeve (green and yellow); this provides equivalent insulation to that provided by the insulation of a single-core non-sheathed cable of appropriate size complying with BS 6004 or BS 7211.