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Thermoplastic-sheathed cable

January 01, 1970

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 twin and earth. In mainland Europe, a round equivalent is more common.

Description edit

 
During the "rough in" stage of a wiring project, TPS cable has been run through holes in wooden supports and protective metal plates have been fastened in place.

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.[1]

Thermoplastic-sheathed cable is more vulnerable to rodent damage and accidental mechanical damage than wiring within electrical conduit or armoured cable.

North America edit

"Romex" redirects here. For the contract bridge bidding system, see Romex system.
 
 
"12/2" NM cable with a yellow colored PVC sheath surrounding two insulated and one bare wires (top) and older cloth-sheathed NM cable (bottom)

In North America, this type of cable is designated as NM cable. NM means "nonmetallic", referring to the outer sheathing; the conductors are still metallic. NM was first listed and described in the NEC 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".[2] Today, the name "Romex" is a trademarked brand of the Southwire Company.[3]

In modern[when?] 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.

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 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[4]

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 cable has four conductors—three 12-gauge insulated wires and a bare copper ground wire.[5]

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.

Australia and New Zealand edit

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, three and earth, 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.[citation needed]

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.[6]

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".[7][8]

Flat TPS is more common than circular, and is used for fixed wiring of domestic and industrial lighting, power outlets, appliances, and HVAC 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.[citation needed]

  •  
    Flat twin and earth conductor TPS cable for single-phase plus earth
  •  
    Cross-section of same cable, showing three stranded inner wires
  •  
    Flat three and earth conductor TPS cable for three-phase plus earth
  •  
    Cross-section of same cable, showing four stranded inner wires
  •  
    Cross-section of cable showing three solid inner wires

United Kingdom edit

In the UK, thermoplastic-sheathed cable in twin and earth (or T and E) format has the circuit protective conductor (CPC or Earth) 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 or ring circuit)
  • 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 edit

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.[9]

See also edit

References edit

  1. ^ [1] 4 November 2011 at the Wayback Machine
  2. ^ "InterNACHI Forum". 3 February 2015. {{cite journal}}: Cite journal requires |journal= (help)
  3. ^ Barker, Bruce. "Old Wiring Methods". The ASHI Reporter. The American Society of Home Inspectors. Retrieved 9 June 2014.
  4. ^ "Types of Electrical Wiring in Homes". Completeelectrical.biz. 8 October 2013. Retrieved 3 March 2015.
  5. ^ "Nonmetallic Cable Sheathing Color Codes". Electrical.about.com. Retrieved 3 March 2015.
  6. ^ "Electrical Wiring Colour Codes". Camtec Electrical Services. 9 March 2018. Retrieved 19 January 2020.
  7. ^ "Electricity and Gas". Renovate.org.nz. 21 March 2011. Retrieved 1 February 2019.
  8. ^ "Compliance of wiring materials in New Zealand homes and building". Level.org.nz. Retrieved 3 March 2015.
  9. ^ "BASEC News". BASEC. Retrieved 8 March 2017.

January 01, 1970
thermoplastic, sheathed, cable, thermoplastic, sheathed, cable, consists, toughened, outer, sheath, polyvinyl, chloride, thermoplastic, covering, more, individual, annealed, copper, conductors, themselves, insulated, with, this, type, wiring, commonly, used, r. 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 twin and earth In mainland Europe a round equivalent is more common Contents 1 Description 2 North America 3 Australia and New Zealand 4 United Kingdom 5 Republic of Ireland 6 See also 7 ReferencesDescription edit nbsp During the rough in stage of a wiring project TPS cable has been run through holes in wooden supports and protective metal plates have been fastened in place 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 1 Thermoplastic sheathed cable is more vulnerable to rodent damage and accidental mechanical damage than wiring within electrical conduit or armoured cable North America edit Romex redirects here For the contract bridge bidding system see Romex system nbsp nbsp 12 2 NM cable with a yellow colored PVC sheath surrounding two insulated and one bare wires top and older cloth sheathed NM cable bottom In North America this type of cable is designated as NM cable NM means nonmetallic referring to the outer sheathing the conductors are still metallic NM was first listed and described in the NEC 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 2 Today the name Romex is a trademarked brand of the Southwire Company 3 In modern when 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 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 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 4 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 cable has four conductors three 12 gauge insulated wires and a bare copper ground wire 5 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 Australia and New Zealand editIn 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 three and earth 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 citation needed 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 6 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 7 8 Flat TPS is more common than circular and is used for fixed wiring of domestic and industrial lighting power outlets appliances and HVAC 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 citation needed nbsp Flat twin and earth conductor TPS cable for single phase plus earth nbsp Cross section of same cable showing three stranded inner wires nbsp Flat three and earth conductor TPS cable for three phase plus earth nbsp Cross section of same cable showing four stranded inner wires nbsp Cross section of cable showing three solid inner wiresUnited Kingdom editThis section does not cite any sources Please help improve this section by adding citations to reliable sources Unsourced material may be challenged and removed January 2021 Learn how and when to remove this message In the UK thermoplastic sheathed cable in twin and earth or T and E format has the circuit protective conductor CPC or Earth 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 or ring circuit 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 editIn 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 9 See also editTough rubber sheathed cable Electrical wiring Electrical wiring in North AmericaReferences edit 1 Archived 4 November 2011 at the Wayback Machine InterNACHI Forum 3 February 2015 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Barker Bruce Old Wiring Methods The ASHI Reporter The American Society of Home Inspectors Retrieved 9 June 2014 Types of Electrical Wiring in Homes Completeelectrical biz 8 October 2013 Retrieved 3 March 2015 Nonmetallic Cable Sheathing Color Codes Electrical about com Retrieved 3 March 2015 Electrical Wiring Colour Codes Camtec Electrical Services 9 March 2018 Retrieved 19 January 2020 Electricity and Gas Renovate org nz 21 March 2011 Retrieved 1 February 2019 Compliance of wiring materials in New Zealand homes and building Level org nz Retrieved 3 March 2015 BASEC News BASEC Retrieved 8 March 2017 Retrieved from https en wikipedia org w index php title Thermoplastic sheathed cable amp oldid 1222895853, wikipedia, wiki, book, books, library,

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