CWS are experts in electrical cable:

The name CWS is synonymous with electrical cable and organisations the length and breadth of the
country turn to CWS for advice and guidance on this bellwether product of British Industry. Cable is a
product with very few experts, but you can be confident that our technical and market knowledge
can guide you into choosing the correct cable type for your application.

Having an unsuitable or incorrect cable manufactured, particularly with its high copper content is a
costly mistake, allow CWS to guide you through the maze of technical and generic terms used within
the cable industry. With our direct access to worldwide manufacturers, this makes CWS one of the
most competitive cable distributors in the UK. We purchase cable in bulk from world renowned
factories and bring those savings direct to you.

Why are there so many different types of cable?

The UK has long been a world recognised authority in the design, specification and manufacture of
cable, and with the different types of buildings we have that require electrification, we begin to
understand why. Below is one example of the Importance of correct compliance and to ensure a
cable installation is as safe.

You may recall the devastating fire at Kings Cross Underground station in 1987 where thirty-one
people lost their lives and scores more were injured. This one incident prompted urgent research
into safer cables, cables that greatly reduced fire propagation but perhaps more importantly, when a
cable did catch fire, it released less smoke and toxic acids – also known as dangerous halogens. The
phrase LSF (low smoke and fume) became commonplace but Low Smoke and Fume remained too
generic a description and unscrupulous manufacturers continued to manufacture cables with less
toxicity than PVC but unfortunately, they did not always go far enough and achieve what we know as
LSOH, Low Smoke Zero Halogen. LSNH, Low Smoke No Halogen, is another term used for these safer
low halogen cables, cables proven, by stringent testing, to emit less than 0.5% of dangerous
hydrogen chloride when burned.

Popular Cable Types used in UK Installations:

Cable Installers, big or small, normally follow drawings when embarking on a new installation and
the design/drawing is normally signed off by a building surveyor, architect or electrical engineer.
With the wide range of trades and professions involved in the specification of a cable install
however, such as electricians, factory maintenance personnel, facilities management persons or an
architect, this leaves the cable types used potentially wide ranging, such as:

Control-flex YY, SY and CY
YY is one of the most basic of cables, having an outer sheath of grey PVC and typically used for
300/500volt Energy Distribution and Control Applications. It is not screened and provides no
mechanical protection.

SY is a braided cable with (normally) a transparent PVC outer sheath. The galvanised steel wire braid
provides some mechanical protection but is not an electrical screen. SY is 300/500volt rated and
used for Energy Distribution and Control Applications. In some sizes, SY is available with a Black UV
rated outer sheath and occasionally, it is required to be made with Low Smoke Zero Halogen
materials.
CY cable is a grey, sometimes black, outer sheathed cable that has a Tinned Copper Wire Braid
(T.C.W.B.) and this braid acts as an electrical screen that provides protection from electrical
interference. CY cable provides no mechanical protection and is 300/500volt rated.

PVC Flexes
This is a range of black and white approved cables rated at 300/500volts and available in 50m or
100m drums. Having an outer sheath of black or white they are typically used for Energy Distribution
and Control Applications. They are not screened and provide no mechanical protection. A 3core for
example would be described as a 3183Y whereas a 4core 3184Y. When ordering this range of cables,
be sure to look for the BASEC approved stamp of approval.

NYY-J
Sometimes known as Hi-Tuff this 600/1000volt cable is also used extensively in mainland Europe for
fixed energy supplies in outdoor and indoor installations and it is UV rated. NYY-J is also used by
many installers in the UK due to cost savings, cost savings primarily because NYY-J is quicker to
terminate (gland off) because it has no braid or armour.

SWA, Steel Wire Armoured cable
Rated at 600/1000volts and used extensively across the UK for fixed energy distribution in industrial
or commercial environments where robust mechanical protection is required. SWA can also be
buried directly underground and comes with a UV rated black sheath. This cable is always insulated
immediately over the copper cores with XLPE, but with the outer sheath two choices are available,
standard PVC or LSOH/LSZH. With armoured cables, always look for the BASEC approved stamp of
approval.

Twin and Earth and Singles Conduit Wiring
Twin and Earth is also known as 6242Y and used primarily in domestic house wiring installations,
with 1.5mm, 2.5mm and 6mm proving popular. 10mm and 16mm tend to be used for wiring electric
showers and cookers but as with all cables, electricians should decide the size. 6242Y is a very cost-
conscious product for UK electricians. It is also available in a Low Smoke Zero Halogen version for
what are typically commercial applications when it is then classified as 6242B.

Single core conduit wiring cable is served with either a PVC outer sheath, 6491X, or a Low Smoke
Zero Halogen Sheathed version, 6491B. It is available from 1.5mm to 10mm in 100m or 500m drums.
However, 6491X or 6491B is also available from 16mmSQ to 630mmSQ. With 6242Y, 6242B, 6491X
and 6491B the only way to ensure quality is to look for the BASEC stamp of approval.

What other cables are used in the UK?

The cables described above provide for approximately 95% of electrical cable installations in the UK.
Other products such as HO7RN-F Rubber cables and Fire Rated Cables in Red (Fire Alarms) or White
(Emergency Lighting) typically make up most of the balance.

Data Cables
From an installation point of view, Data Cables are often considered separate to power and control
cables and typically, Data orientated installers are used for Data Installations. Cat5e and Cat6 will be
products you will likely recognise but just like power cables, consideration should always be given to
quality. At the turn of the century, the UK was awash with substandard data cable known as CCA, or
Copper Clad Aluminium – the only way to guarantee a good data signal is to use pure copper
cores/pairs, not inferior conductors such as aluminium with a copper cladding.