Screened wire


 
A much smaller version of co-ax, this is used for low level audio signals. The screening eliminates hum pick-up, though there are other ways to do that too. Use of long lengths of screened cable for audio can easily run into issues.
 
 

Co-axial cable (normal and satellite quality)

  • High frequency uses required co-ax cable until recently. (Now its possible to stream video over twisted pair.)
  • TV
  • Satellite
  • Baseband video (from VCRs, cameras etc)
  • Radio aerial (for FM, DAB or DX reception)

It is important to use the right type of co-ax for each app. They are far from all the same, and some common co-axes simply won’t work at TV or satellite frequencies. CAI approved satellite cable is good for all the above apps, using just this type of co-ax maximises the abilities of the wiring system.

Cat 5

  • Uses as multicore cable, plus also good for computer networking
  • Cat5e has better specs than Cat5, and is the currently recommended networking cable.
  • Cat5e is recommended for phone extensions now, as these are liable to carry broadband signals, even if they don’t already.
  • Beware of using cat5e with alarms, as alarm accessory terminations are explicitly designed for stranded cable (as required by BS). They turn out to be unreliable long term with solid core. If its wished to fit an alarm to cat5, as no alarm multicore was installed, short, stranded terminating wires can be attached at each end of the cable.

Multicore alarm cable

  • For most multicore uses
  • Alarms
  • Intercoms
  • Fire alarm systems
  • Most 2 core uses as well
  • Low current rating
  • Cores can be parallelled to enable power distribution, though ampacity is still limited
  • Alarm cable to BS has 0.22m^2 conductors

Speaker wire


Stranded flexible 2 core wire
Available in a few different copper sizes each with their own current rating.
polarity is indicated by any of: printed stripe on one side (typical on black wire)
tiny moulded ridge along one edge (typical on white wire)
different conductor colours, one is tinned (typical with clear wire)

clear wire is a bit less noticeable than the others
 

Bell Wire

Lowest cost 2 core wire.
Solid core
1A rated
Suitable for most low power low frequency uses, eg: intercoms
bells
remote control
low power distribution
low power speakers (up to 8watts for 8 ohm, 4w for 4 ohm) (that’s real rms watts, not pmpo watts)
 

Enamelled Copper

Where installation with no disruption of decor is necessary, this can be achieved with enamelled copper wire. This unique type of wire has its own set of issues, it can’t be treated like pvc cable, but it can be routed in some surprising places while remaining out of sight and not affecting the decorations.

The big advantage is that its ultrathin profile renders it nearly invisible, enabling fitting in all sorts of places pvc cable would not go. Sizes down to 0.3mm are practical for a wide range of uses, and much thinner sizes are practical for at least some applications.

Routing examples:

  • In cracks along corners or up walls
  • Along top of skirting
  • Tucked under or behind skirting
  • Under carpet – but keep it at the edge to avoid damage
  • Down corners of walls, covered completely with a thin smear of filler.
  • Through cracks & gaps in floors, frames & walls

The disadvantages are:

  • Not as robust as pvc cable, and should be kept from any more than occasional user contact for this reason.
  • Should not be moved or reused once laid, as the enamel will crack and shorts occur.
  • Never re-use enamelled copper wire. Many have tried it, and it rarely works.
  • Single core cable only
  • Where cores are not spaced from each other they should be completely immobilised to avoid the chance of later shorting. This is easily done in most cases.
  • Ends should be terminated to something fixed rather than a flying connector, as it does not like movement.
  • Wire can be fixed with a drop of glue.

Single pvc insulated wire

  • Stranded
  • Enables any desired number of cores to be used
  • Not good for computer networking
  • Available in various copper sizes
  • Larger sizes suited to power distribution
  • A small number can be mixed in with other wire types for LV power distribuion
  • Not an wire ideal type, but can be used if you already have a large quantity of such wire.