One of the first things you learn in this industry is the different types of wires and cables. It is quite important to know what the different types are and when to use them, this article provides a look at a few main types used in the construction industry.

Please note that this article merely provides a general overview into the main types of cables, for specific installations please consult a licensed electrician or local electrical safety inspector.

Cables like most other electrical have different kinds of ratings, i.e. voltage, fire rating, temperature etc. To understand the different types of cables better we first need to look at the different kinds of insulation materials that exist.

So what are the main types of power cables used within the commercial construction industry? After looking around I found a Nexans brochure which best explained the types of cables used in Canada-the below descriptions is quoted exactly from their brochure. While doing research for this project I noticed that cable types used in the US is quite different to the ones used in Canada - but lets save that for a later article.



Armoured Cables

AC90 is used in stores, small factories, apartments and similar buildings,where some mechanical protection is required. It has RW90 insulated 600V conductors (usually copper) cabled with a bare bonding wire, andenclosed in armour made of interlocked aluminum strip. AC90 must not beburied, nor used in wet locations. It is an inexpensive alternative to wirein conduit.
CORFLEX (CSA type RA90) is similar to ACWU - but DIFFERENT. There is no bonding wire because Corflex has an aluminum sheath that is a 'tube' (not a wrapped strip like ACWU) that can be used as an equipment bond. It is water and gas tight, can be bent by hand, and holds the shape made. Approved for use in hazardous locations it has excellent fire, water and crush resistance. It can be installed on hangers, as it holds its shape better than interlocked armour cables. Corflex is excellent for use in high rise apartments, hospitals, schools, shopping centres and factories. Corflex is 600 volt rated. Available in single conductors of both copper and aluminum alloy.

ACWU is the same as AC90 but has a PVC plastic jacket over the armour. This permits its use for direct earth burial and in wet locations. Conductors are usually aluminum alloy, but may also be copper. In single conductor cables there is a concentric copper bonding wire over the insulation, which is sized in accordance with the electrical code. When marked "HL" ACWU can be used in hazardous locations. It is a cheaper and less robust cable than Teck. ACWU is 600 volt rated.


TECK is the most widely used, abuse resistant, easy to install and readily available cable for industrial use. It has been the backbone of power systems for several years. Usually made of copper conductors with RW90 insulation. There is a PVC jacket between the conductors and the interlocked aluminum armour so that if the cable is crushed the edge of the armour will not cut the insulation. Covered by an outer PVC jacket TECK has excellent fire, water and cold-bend characteristics. It may be directly buried and used in wet locations


Most ARMOURED CABLES can be directly buried.


Direct Buried Cables


NMWU has copper conductors with thick PVC insulation; assembled with a bare copper bond wire; and encased in a thick PVC plastic jacket. Excellent for buried runs to lawn lights, sheds, garages, etc. and also for use to (and in) barns and animal pens.


RWU90 is RW90 with thicker cross-linked polyethylene (XLPE) insulation for direct burial in earth or in duct and is rated 1000 volts. It is tough and has excellent water resistance.


Conduit Cables

RW90 is insulated with cross-linked polyethylene (XLPE), over copper or aluminum conductors. It is mechanically and electrically very strong. Flame retardant jackets are available on special order. The XLPE insulation has very good cold weather characteristics, and excellent water resistance.
It can be used in wet locations and underground ducts. RW90 is poor on ultraviolet (sunlight) resistance unless made with special additives and printed "OUTDOOR" on the outside of the insulation.

T90/TWN75 is copper conductor insulated with a thin layer of PVC plastic covered with a skin of nylon (like nail varnish). It is very useful when a lot of conductors must be put into a small conduit. Solid and stranded conductors are available in many different colours. It is rated 90°C in dry
locations, but only 75°C if wet. It must not be exposed to ultraviolet rays (sunlight) as it will crack. It is not as robust as RW90, and must be handled with care at low temperatures.

TW75 is a single copper wire covered with PVC plastic, commonly used for service entrances connecting the utility power supply conductors to the house or other building. It must be carefully handled at low temperatures but withstands both rain and ultraviolet rays from the sun. The most common service entrance sizes are stock. TW75 has mostly been replaced by T90/TWN75, with protection where exposed to sunlight.


RW90, TWN75 & TW75 may be installed in underground ducts,
but must NOT be directly buried.

Other types

ISO-BX is the same as AC90 BUT has an additional GREEN conductor, providing an isolated insulated ground, to give extra protection to sensitive equipment. ISO-BX is 600 volt rated.

NMD90 is common house wire. It is designed for use indoors, in dry locations, and away from the weather. It must NOT be buried or used in wet locations. The slight dampness found in some basements will not hurt it. A bare copper bonding (ground) wire is always included to permit safe operation of attached equipment. The plastic covering is not designed for installation at low temperatures, and it is good practice to warm the spools before unrolling the wire in winter. NMD90 always contains a white NEUTRAL wire, except for NMD (Red) HEATEX.

NMWU is similar in appearance to NMD, it is in fact quite different. This wire has very thick PVC insulation on the individual conductors, and is then covered with a thick PVC jacket making it suitable for direct burial. It is a very good cable to use for supplying a garage, garden shed or lawn lights. The #2 gauge and larger is suitable for 100 amps. NMWU can be used in wet locations, and in barns and other animal enclosures where not exposed to mechanical injury.


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