Although part of the audio range, loudspeaker wiring is very different and needs a little consideration. Little loudspeakers in equipment may be wired up using almost any wire, as may intercom type circuits and so on.

Hi-fi loudspeaker cabling and In-Car Entertainment speaker wiring is much more critical. It is very easy to drop a significant part of the output of an audio amplifier over a medium to long run of inadequate but inexpensive speaker cable. Many people automatically use a thin figure of eight “Zip” wire for speaker connections but for any amplifier delivering over a few Watts, a thicker and more substantial cable is needed for a quality reproduction of sound without burning part of your output as heat and having to have the volume higher to achieve the same volume at lower quality.

Look at heavy duty and Hi-fi loudspeaker cables or, if the increased bulk of those is a problem, there are several special flat variants that will go under the carpet easily. Silver plated and oxygen free copper are also available and provide a very clean transfer of power to your loudspeakers.


The first thing to consider with an RF cable is impedance. Impedance is a combination of DC resistance as well as capacitive and inductive effects in the cable. It may be considered as the effective resistance of a cable to an AC signal.

Most RF equipment is designed to work with a cable of a specific impedance. TV’s, video recorders and satellite equipment are designed to use 75 Ohm cables, whereas radio transmitters and some receivers are designed to use 50 Ohm cable. It is important to select a cable with the correct impedance for the job, otherwise a bad match will be made between the equipment and signal will be lost, resulting in poor reception. In the case of transmitters, it is possible that this will cause the output stages to heat up in use, or even burn out.

The other associated figure to look at when choosing an RF cable is attenuation. Attenuation is a measure of how much signal you will lose over a given length of cable at a stated frequency, expressed in Decibels. The explanation of both impedance and attenuation is beyond the scope of this guide, but suffice it to say that a cable of the correct impedance for the application, with the lowest attenuation figure at the frequency range to be used, will give the very best results, although the voltage rating of the cable is also important at very high transmitter output levels.

Impedance is also important for some professional audio uses, such as the use of balanced microphones in studio or stage situations. Check the impedance rating of the equipment and use the correct cable and connectors for the job.


Networking connections that use the BNC connector are designed to use 50 Ohm RF cable to interconnect computer equipment. Newer networking connections tend to be made using special multi-way twisted pair cables that help to reduce both radiation of the very sharp edged RF data signals as well as reducing the likelihood of pick up of interference from other electrical equipment.
 

There are various standards for these data cables (Category 5 for example) and it is always best to check the instructions supplied with each unit before choosing a cable.


If you intend to do a lot of cabling, there are a number of special cable stripping tools that will make the job a lot easier.

Many connectors need soldering onto the cables and sharp cutters, a craft knife and small screwdriver for any screw-fixed connectors will be needed.

A multimeter or continuity tester is ideal for reassuring you that your completed cable and connector assembly really does connect as you think it does, with no open or short circuits that could cause damage or other problems later.

Consider the use of conduits or trunking to box up, hide and protect long cable runs. Wiring inside equipment may be secured by using cable ties, lacing cord or spiral wrapping. There is a large range of different cable clips that will also help tidy your wiring and keep it in place after installation.

If your cables or wires have many different terminations, you may wish to use coloured or numbered sleeving at each end of each wire to aid later fault finding or rewiring. Heat shrink sleeving will allow you to join cables in places where no connectors are required, and then shrink the sleeving over the individual joins to remake the insulating layer, or just provide an additional protective layer for a cable in a vulnerable position.

Cable glands and grommets will allow you to make neat entry to boxes or through panels, and will prevent the cable chafing on metal edges.
It is never ideal to run a cable across the floor but, if you have no alternative, consider using a cable protector, which is a heavy rubber strip the cable lies protected inside on the floor, shaped to minimise tripping over it.


It seems fairly obvious that the ends of your cable will somehow need to be securely attached to the equipment, either by directly soldering each conductor to a terminal or tag, or by screw or clamp terminals, or via a suitable set of connectors. Check before choosing connectors that their current and voltage rating is sufficient and safe for the job in hand.

RF cables must be properly connected and joined by suitable RF connectors of the same impedance. Use of the wrong connector, or a hard wired soldered or screw terminal joint, may result in a break in the smooth transfer of RF energy that may result in the signal being reflected back up the cable instead of passing through it.

Note that, especially for RF, a soldered connector is usually far better than a screwed one, and that TV aerial and distribution wiring should always be soldered for best long term results.

We hope that this guide to cables has helped you to think about what you need from your cables and wiring, and that you now feel ready to make your choice.