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CABLES AND WIRES

Strands make a wire. Wires make a cable.

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Joining cable Fixing to a wall Care of cables Common types Tools Tips and tricks

Joining cables back to top

Cabtyre or flex
Tools and things for this job
When joining these cables try to cut the wires in such a way that the joints are offset to each other to prevent the completed joint becoming too thick.

Click for bigger picture Click for bigger picture Never twist the two bared wires together into a little tail, unless you are using Scru-its for insulation, as this will make the join unnecessarily thick and strands may stick through the insulation causing a short-circuit, but turn them around each other horizontally and solder the join (See:How to solder).

Slip shrink sleeving of the correct thickness over the wire before joining and heat the sleeving one wire at a time. If you are using insulation tape also insulate each wire as you join it. Do not break off the tape around each wire but wrap it around the wires as you join. Complete the join by wrapping all the wires together.  Try to stretch the tape as much as possible to ensure good adhesion of the tape to itself.

Special waterproof joiners are now also available for cabtyre. Another alternative is to use connecting blocks but these are difficult to insulate.

 Surfix cable.
Tools and things for this job
As this has a single core strand it should only be joined with ferules or connecting blocks. Shrink sleeving or insulation tape can be used for insulation . If the cable is  used underground or outdoors a special waterproof joiner must be used.

 Aerial cable
Tools and things for this job
This has an inner core single wire with a finely woven copper screen and foil around it.  This type of cable can only be joined by using special joiners sold by hardware and electrical stores. Male and female plugs are required for this operation.

Cut the outer insulation away carefully so as not to damage the shield. Push the shield back over the inner insulation. Carefully cut the insulation of the inner strand  and remove.

Fasten the male to one wire and the female to the other. These plugs come with a thin membrane around the hole where the wire passes through the casing. If you have the thicker type of aerial cable simply break away the membrane with a star screwdriver or any blunt object that will pass through the hole.

Joining different types of cable
Tools and things for this job
This happens most often in ceilings when lamps are attached to the house wiring. This can be done with a connector block or the wires can be twisted together and a "Scru-it" placed over the connection. "Scru-its" are made of porcelain or plastic and have an inner tapered thread to screw over the wires.

Fixing wires to a wall back to top

Flex or ripcord, telephone extension cables and thin ripcords are fixed most neatly to a wall or along a skirting using a special clear adhesive available from security shops, hardware stores and electrical dealers. Run a thin bead of glue for about one and a half meters and push the flex into the glue with a screwdriver but be sure not to apply too much pressure as this can stretch the wire unnecessarily. Before going round a corner it is a good idea to let the glue set for about 5 minutes or longer to prevent the already stuck cable from pulling away from the wall. Thicker cabtyre and aerial cable can also be secured in this way but only if the cable runs in a corner or next to a wall on a skirting.

Plastic cable clips, both flat and round, fitted with a steel pin suitable for all materials, are available in a multitude of sizes but, unfortunately, only in white. Push the clip over the cable (it should be a tight fit) and hammer the nail into the wall or other surface. Place a clip approximately every 60 cm if the cable runs on a vertical or overhead surface. On horizontal surfaces a clip every 1 to 2,5 metres will suffice.

For cable thicker than 16 mm outside diameter it is better  to use saddles. If the cable is to be fixed to masonry work small nail-in anchors are available for this purpose. (See fasteners and glues.)

Care of cables back to top

As the strands of all cables and wires are twisted clockwise in the manufacturing process they should always be coiled or rolled up left-handedly. This is not a big problem when using extension reels but when the extension is coiled in the hand one end should be held in the left hand and loops placed in a clockwise direction. Should the cable you are coiling  make “figure of eight” loops the coiling direction will be wrong and you should start again. Click for bigger picture This will prevent kinks in the inner cable which can, with time, become extremely dangerous or simply break leaving you with a useless extension cable. Never coil wires  around your hand and elbow! You will not be able to see when you are coiling the wrong way and you could also get your forearm tied to your upper arm. A very uncomfortable situation!

For long extensions it is a good idea to store the cable in a bucket. Make a hole at the bottom large enough to pass the plug through and coil the extension clockwise into the bucket. Leave enough wire outside of the bucket at the bottom to reach your outlet sockets comfortably. A few smaller holes in the bottom of the bucket will ensure that the cable stays dry at all times. Storing cables in a dry location such as your Sacramento garage cabinets is always a necessity.

Do not work with a coiled extension for a long time. It is better to uncoil the extension in large loops if you are working close to the outlet socket than to leave it coiled up. The induced current of a tightly coiled cable, especially on cable reels, will set up a magnetic field that can heat up the cables with disastrous results!

Another way of storing shorter extensions is to place large loops in your left hand in a clockwise direction holding both sides of the loop together. Take one of the loops and wrap it twice round the coil about a third from one end. Finally insert the wrapping loop through the small eye of the coil and pull tight. Hang the coil by this loop.

Common types of cableback to top

Aerial cable
Actually called “screened single-core co-axial communication cable”, has a single copper strand insulated by thick plastic and surrounded by foil and screen wire. It is used to connect the aerial to the TV and is sold in two sizes.

Flat surfix cable
(or  Norsk cable) and
round surfix cable
Very popular cables for domestic and industrial wiring. They have two single copper strands insulated with PVC and a bare single copper earth wire.  Norsk cable has the earth wire between the two strands. Round surfix cable has an extra strand of PVC material embedded to maintain its “roundness”. Surfix cable also has an outer foil shield to prevent induction. It is sold in a variety of sizes. Norsk cable can be bought in black or white whereas round Surfix is always white.

Flex or ripcord
A twin stranded wire normally used for bells, lamps and the wiring of alarm systems. It does not have an earth wire. For some ripcords the outside of one strand is marked with either a ridge or a different colour to identify which is to be used for the positive (live) and which for the negative (neutral) side. However most ripcords have a red and white satin insert in one strand for this purpose.

Domestic flex
A three core cable with a cotton outer covering used mainly for irons.

Cabtyre: twin core
Mostly used for lamps and other appliances that do not have to be earthed. It is sold in different sizes but almost always in white.

Cabtyre: 3-core
The most popular cable of all. It is extensively used for extensions and supply cables to appliances. It is sold in a variety of sizes and colours.

Cabtyre: multi-core
Seven core is the most popular variety of this cable. It is used for caravans and trailers.

House wire
Used for the internal wiring of buildings. It is sold in a variety of thicknesses and colours and has a seven strand core. The earth wire is always bare.

Tools mentioned on this page
back to top
  1. Crimping and stripping pliers
  2. Longnose pliers
  3. Rubberband
  4. Diagonal cutter
. (See: Electrical tools)


Tips and tricks back to top

Click here for bigger picture To prevent a sudden disconnection when joining two extensions or plugging into an extension, knot the two cables together with a simple knot before plugging in.

 

 

Always buy extension cables, ladders, rope and garden hose longer than you think you will need!



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