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File:Tps-3core.png, alt=Broad white-coated cable, cut away to show green, red and black coated wires, Flat
A thermoplastic-sheathed cable (TPS) consists of a toughened outer sheath of polyvinyl chloride (PVC) thermoplastic, covering one or more individual annealed copper conductors, themselves insulated with PVC. This type of wiring is commonly used for residential and light commercial construction in many countries. The flat version of the cable, with two insulated conductors and an uninsulated earth conductor (all within the outer sheath), is referred to as ''
Each of the current carrying conductors in the "core" is insulated by an individual thermoplastic sheath, coloured to indicate the purpose of the conductor concerned. The protective earth conductor may also be covered with green/yellow (or green only) insulation, although, in some countries, this conductor may be left as bare copper. With cables where the current-carrying conductors are of a large cross sectional area (CSA), the protective earth conductor may be smaller, with a lower ''continuous'' current carrying capacity. The conductors used may be solid in cross section or multi-stranded.
The type of thermoplastic, the dimensions of the conductors and the colour of their individual insulation (if any) are specified by the regulatory bodies in the various countries concerned.
Thermoplastic-sheathed cable is more vulnerable to rodent damage and accidental mechanical damage than wiring within
circuits.
: Yellow: 12 AWG wire (3.31 mm2) for 20-amp circuits.
: Orange: 10 AWG wire (5.26 mm2) for 30-amp circuits.
: Black: 6 or 8 AWG wire (13.3 mm2 or 8.37 mm2) for 60- and 45-amp circuits, respectively.
: Grey: usage for underground installations, designated as "underground feeder" (UF) cables.
The outer jacket is labeled with letters that show how many insulated wires are concealed within the sheath. This does not include the uninsulated ground wire. For instance, if the cable lists "12-2 AWG", it means there are two insulated 12-gauge wires (a black and a white wire), plus a ground wire. If the label says "12-3", this is a three-conductor, 12-gauge cable with a bare copper ground wire understood to be included.
Different types of cables are approved for different applications; the cable used for interior wiring in dry locations is different from the types approved for underground burial, direct embedment in concrete, or service entrance use.
twin and earth
Twin and earth (often written "T&E" and sometimes "T and E") cable is a colloquial name in the UK, Australia, New Zealand and other countries for a type of flat sheathed fixed mains electricity cable, containing two insulated current-carrying c ...
''. In mainland Europe, a round equivalent is more common.
Description
Each of the current carrying conductors in the "core" is insulated by an individual thermoplastic sheath, coloured to indicate the purpose of the conductor concerned. The protective earth conductor may also be covered with green/yellow (or green only) insulation, although, in some countries, this conductor may be left as bare copper. With cables where the current-carrying conductors are of a large cross sectional area (CSA), the protective earth conductor may be smaller, with a lower ''continuous'' current carrying capacity. The conductors used may be solid in cross section or multi-stranded.
The type of thermoplastic, the dimensions of the conductors and the colour of their individual insulation (if any) are specified by the regulatory bodies in the various countries concerned.
Thermoplastic-sheathed cable is more vulnerable to rodent damage and accidental mechanical damage than wiring within electrical conduit
An electrical conduit is a tube used to protect and route electrical wiring in a building or structure. Electrical conduit may be made of metal, plastic, fiber, or fired clay. Most conduit is rigid, but flexible conduit is used for some purpos ...
or armoured cable
In electrical power distribution, armoured cable usually means steel wire armoured cable (SWA) which is a hard-wearing power cable designed for the supply of mains electricity. It is one of a number of armoured electrical cables – which include ...
.
North America
In North America, this type of cable is designated as NM cable. NM means "nonmetallic
In chemistry, a nonmetal is a chemical element that generally lacks a predominance of metallic properties; they range from colorless gases (like hydrogen) to shiny solids (like carbon, as graphite). The electrons in nonmetals behave differentl ...
", referring to the outer sheathing; the conductors are still metallic. NM was first listed and described in the NEC
is a Japanese multinational corporation, multinational information technology and electronics corporation, headquartered in Minato, Tokyo. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as NEC. It prov ...
in 1926, but it was invented a few years earlier by the Rome Wire Company in 1922 in Rome, New York, and marketed under the trade name "Romex". Today, the name "Romex" is a trademark
A trademark (also written trade mark or trade-mark) is a type of intellectual property consisting of a recognizable sign, design, or expression that identifies products or services from a particular source and distinguishes them from others ...
ed brand of the Southwire Company.
In modern products, the color of the NM cable sheath (or jacket) indicates either the gauge of the current carrying conductors within it, or special properties of the sheathing itself. Cables found in older installations may not conform with this colour coding
A color code is a system for displaying information by using different colors.
The earliest examples of color codes in use are for long-distance communication by use of flags, as in semaphore communication. The United Kingdom adopted a color ...
.
The following are nominal current ratings for copper conductors; long runs may require thicker wires to minimize voltage drop.
: White: 14 AWG wire (2.08 mm2) for 15-amp #REDIRECT Amp #REDIRECT Amp
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{{Redirect category shell, {{R from other capitalisation{{R from ambiguous page ...Australia and New Zealand
In Australia and New Zealand, the colour of the external sheath is usually white for flat TPS or black for circular TPS but several other colours are available. Wire sizes of 1–6 mm2 cross-sectional area (CSA) are available with the outer sheath covering the cores. TPS cable is available in several conductor configurations: single, twin,twin and earth
Twin and earth (often written "T&E" and sometimes "T and E") cable is a colloquial name in the UK, Australia, New Zealand and other countries for a type of flat sheathed fixed mains electricity cable, containing two insulated current-carrying c ...
, three and earth
Ground and neutral are circuit conductors used in alternating current electrical systems. The ground circuit is connected to earth, and neutral circuit is usually connected to ground. As the neutral point of an electrical supply system is often ...
, and four and earth, the latter two for three-phase supply. Although available in the larger sizes, solid conductors are rarely used with wire sizes greater than 1 mm2 CSA, since the small increase in manufacturing cost of stranded conductors is far outweighed by the relative ease of working with them, especially at the points of termination.
Unlike in North America, the existence of the earth wire within the sheath is always specified if it is present (e.g. twin cable has two conductors and twin and earth cable has three.) The earth conductor is always stranded (unlike North American usage), with the exception of 1 mm2 cables, and covered with green-yellow striped plastic insulation. In older cables the plastic insulation of the earth conductor is green.
Prior to the introduction of TPS cable, tough rubber sheathed (TRS) cable was used. Because of this, TPS is sometimes referred to as "tough plastic sheathed".
Flat TPS is more common than circular, and is used for fixed wiring of domestic and industrial lighting, power outlets, appliances, and HVAC
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
units. Circular TPS is common in industrial and commercial installations but generally not in domestic installations. It may be more difficult to strip the outer sheathing from circular TPS than from flat TPS.
twin and earth
Twin and earth (often written "T&E" and sometimes "T and E") cable is a colloquial name in the UK, Australia, New Zealand and other countries for a type of flat sheathed fixed mains electricity cable, containing two insulated current-carrying c ...
conductor TPS cable for single-phase plus earth
File:tps cross 3.png, Cross-section of same cable, showing three stranded inner wires
File:Tps-4core.png, alt=White-coated cable, cut away to show green, blue, yellow and red coated wires, Flat three and earth
Ground and neutral are circuit conductors used in alternating current electrical systems. The ground circuit is connected to earth, and neutral circuit is usually connected to ground. As the neutral point of an electrical supply system is often ...
conductor TPS cable for three-phase plus earth
File:tps cross 4.png, Cross-section of same cable, showing four stranded inner wires
File:Electric guide 3×2.5 mm.jpg, Cross-section of cable showing three solid inner wires
United Kingdom
In the UK, thermoplastic-sheathed cable in twin and earth (or T and E) format has the circuit protective conductor (CPC or Cearth) uninsulated (bare) and of reduced diameter compared to the main cores. Green and yellow sleeving is sold separately, to be applied at the ends. The cross section on the main conductors is given first, and then the cross-section of the CPC. Standard UK metric twin and earth cable sizes *1/1 mm2 and 1.5/1 mm2 have solid conductors and CPC (primarily used on low power lighting or alarm circuits) *2.5/1.5mm2 has a solid CPC and may have solid or stranded conductors (primarily used for socket circuits, radial orring circuit
In electricity supply design, a ring circuit is an electrical wiring technique in which sockets and the distribution point are connected in a ring. It is contrasted with the usual radial circuit, in which sockets and the distribution point a ...
)
*4/1.5 mm2 and 6/2.5 mm2 have stranded conductors and a solid CPC (fixed high power equipment or sub-mains)
*10/4 mm2 and 16/6 mm2 have stranded conductors and CPC (fixed high power equipment or sub-mains)
In older properties (pre-1970) cable with imperial sizes are found, sometimes without CPC.
Mainland UK wiring regulations do not at present (BS 7671:AMD3) acknowledge twin and earth or flat TPS with a full sized and insulated (G/Y) earth conductor as a valid cable type, which may be awkward for contractors who work cross-border with the Republic of Ireland.
Also available in smaller conductor sizes are versions containing three current-carrying conductors and a circuit protective (earth) conductor. These configurations are commonly used for applications such as switched light circuits, battery-backed emergency lighting which requires a switched and unswitched supply, extractor fans with a run-on timer which require a switched and unswitched supply, mains-powered interlinked smoke alarms, and central heating thermostats.
There is an overall sheath of grey PVC (BS 6004), or white for low smoke compound (BS 7211), although prior to 2005 white PVC was also available.
Republic of Ireland
In the Republic of Ireland the situation is different from that in the UK. Prior to 2013 IS 201-4:2001 ( I.S. 201 part 4: PVC and Low Smoke Halogen Free Sheathed cables for fixed wiring) permitted both the UK style of twin and earth, and also a version with a CPC with a cross-section equal to that of the main conductors and insulated in green and yellow inside the full length of the cable. However, from 2013, the option for the uninsulated and reduced CPC has been removed from the standard IS 201-4:2013, and as such is no longer permitted in new installations in the Republic of Ireland.See also
*Tough rubber-sheathed cable
Tough rubber-sheathed cable is a type of cable which normally consists of a black outer sheath of rubber with several conductors inside. The rubber provides an abrasion-resistant, corrosion-resistant, waterproof, protective covering for an insul ...
*Electrical wiring
Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure.
Wiring is subject to safety standards for design and installation. Allowable ...
*Electrical wiring in North America
Electrical wiring in North America follows the regulations and standards applicable at the installation location. It is also designed to provide proper function, and is also influenced by history and traditions of the location installation.
The ...
References
{{DEFAULTSORT:Thermoplastic-Sheathed Cable Power cables