Electrical House Wiring

 

Information about the electrical wiring in the house;

Usually concealed behind the wall plaster or run in the void (space) between floors.

Preparation
Types of wall construction
Removing a small strip of wallpaper for the channel
Cutting channels and fixing to masonry
Fixing recess plates to plaster board
Running cable through dry wall partitioning
Running cables under floors

Safety first
Never work on any part of the electrical installation without first switching off the supply at the consumer unit and, where possible, removing the circuit fuse. Always unplug any electrical appliance before doing any work on it. Check all connections are secure and all covers have been replaced before you turn the electricity on again.

Seeking professional help or advice
If you don’t feel competent to do a particular job, always seek the advice of a professional electrician. Make sure that any person you hire is fully qualified. A person registered with the Electrical Contractors Association/ NICEIC, will be approved for undertaking this type of work and will be well versed in all the wiring regulations for electrical installations in buildings.

Preparation
Even small modifications to the wiring will generally involve some chasing of channels in the plaster. Don’t be put off by the thought of the likely mess or the possible damage to room decoration. With a little planning and care whilst undertaking the work, the disruption should be minimal. On completion, the surface can be restored to its original condition without any need for extensive redecoration.

Types of wall construction.
The internal walls in the home are normally either plaster surface on a masonry wall or plaster board stud construction. Very modern houses can also have proprietary dry partitions for non-load bearing walls or partitions.

Removing a small strip of wallpaper for the channel
Using the edge of a builders 600mm spirit level, on the wall mark out a 250mm wide strip for the position of the channel to be chased out. Then, using a steel straight edge and a sharp blade cut down either side of the wallpaper. This provides a good edge for re-papering up to when the job is completed. Very carefully, ease off this strip of wallpaper.

Cutting channels and fixing to masonry
At the appropriate height, hold the metal mounting box against the wall and mark round it with a pencil. Then mark out the channel to be chased out. Using a bolster or a cold chisel cut away the plaster within the marked areas. Cut the channel partially into the brick work, and to recess the metal box, use a masonry drill to bore a series of holes and then cut away with a cold chisel.

Fixing recess plates to plaster board
For a studded or a dry lined wall, it is fairly easy to cut out a close fitting hole to recess the metal box. Cables can be fished through the cavity between the plasterboards, although, there may be some difficulty when passing cables around any horizontal struts or noggins.

Running cable through dry wall partitioning
The cutting out and fixing of metal boxes is similar to the methods used for studded wall partitions. To run the cables vertically through the honeycomb supports between the outer boards, a series of slots can be cut above each other at about 250mm spacing. Use a metal rod to clear a path for the cable running between slots.

Running cables under flooring
Use a small cutting disc to cut the tongue on both sides. Lift the floorboard at a join using a bolster, otherwise prise up near the middle. Wedge up the board and saw across central to the joist underneath. Where cables run across the joists pass through holes drilled in the centre.

 

In a garage, cellar or workshop

PVC sheathed cables can be clipped to the surface of a wall or ceiling without any further protection.

Keeping the cable runs straight.
Fixing the cable neatly
Attach the Clips

Tools
Pliers, side cutters, lump hammer, small hammer, electric drill, masonry drills, blade knife, wire strippers, screwdrivers, junior hacksaw, multimeter

Materials
Surface type mounting boxes, single pole light switches, loop-in ceiling roses, twin switched 13A socket outlets, 1mm 2 twin and earth cable with cable clips, Surface type mounting boxes, single pole light switches, loop-in ceiling roses, Twin switched 13A socket outlets, 2.5mm 2 twin and earth cable with cable clips, earth pvc sleeving, woodscrews and plastic fixing plugs,

Safety first
Never work on any part of the electrical installation without first switching off the supply at the consumer unit and, where possible, removing the circuit fuse. Always unplug any electrical appliance before doing any work on it. Check all connections are secure and all covers have been replaced before you turn the electricity on again.

Keeping the cable runs straight
The cable is secured to the surface with plastic cable clips. Use the right size of clip for the particular size of cable. In theory, the clips can be fixed directly into the various types of wall surface. However, keeping the runs straight, whilst ensuring the cables are secure, can be difficult. Clipping the cable drops to wooden battens or covering the cable runs with plastic channel will improve the appearance.

Position of the electrical accessories in the kitchen
Clips should be nailed from the same side of the cable. For vertical drops the spacing should not exceed 400mm, horizontal runs require a spacing no greater than 250mm. Mark out the run and clip positions using the edge of a builders 600mm spirit level.

Attaching the clips
Work from one end of the run, keep the cable taut and avoid kinks, push the clip onto the cable and press both down to the surface whilst fixing the nail.