Difference between revisions of "Flex"

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(→‎Part 2 of the Designation: add note on Tinsel construction)
(Laying flat section)
 
(11 intermediate revisions by 2 users not shown)
Line 1: Line 1:
−
[[image:Cavo3x1.5-2.jpg|thumb|3 core pvc flex]]
+
[[image:Cavo3x1.5-2.jpg|right|200px]]
  
 
'''Flex''' is stranded electrical wire used for all plug-in mains appliance leads. It is also called flexible cable.
 
'''Flex''' is stranded electrical wire used for all plug-in mains appliance leads. It is also called flexible cable.
Line 7: Line 7:
  
 
==Colour==
 
==Colour==
−
[[image:Cable colours 1179-3.jpg|thumb|New & Old]]
+
[[image:Cable colours 1179-5.jpg|right|200px]]
  
 
Current colours:
 
Current colours:
Line 24: Line 24:
  
 
==2 Core Flexes==
 
==2 Core Flexes==
−
[[image:Flex 2 core flat 835-3.jpg|thumb]]
+
[[image:Flex 2 core flat 0835-8.jpg|right|200px]]
 
Flexes are available with 2 or 3 cores (conductors). 2 core flex is only suitable for appliances that don't need an earth connection (marked [[image:DoubleInsulated.jpg]]), and should not be used for extension leads with 3 pin sockets.
 
Flexes are available with 2 or 3 cores (conductors). 2 core flex is only suitable for appliances that don't need an earth connection (marked [[image:DoubleInsulated.jpg]]), and should not be used for extension leads with 3 pin sockets.
  
 
2 core flexes are available in both round and oval shape. Oval (flat) uses less material, but any twisting of the flex is visible, whereas it isn't with round.
 
2 core flexes are available in both round and oval shape. Oval (flat) uses less material, but any twisting of the flex is visible, whereas it isn't with round.
−
 
  
 
==Multicore==
 
==Multicore==
−
[[image:Flex 4 core 380-3.jpg|thumb|4 core]]
+
[[image:Flex 4 core 0380-5.jpg|right|200px]]
 
Multicore mains flexes are also available for those uncommon tasks requiring more conductors. Non-mains multicores, such as [[Low Voltage Wiring|alarm cable]], are not suitable for mains use.
 
Multicore mains flexes are also available for those uncommon tasks requiring more conductors. Non-mains multicores, such as [[Low Voltage Wiring|alarm cable]], are not suitable for mains use.
−
 
  
 
==Insulation==
 
==Insulation==
 
===PVC===
 
===PVC===
−
[[image:Flex blue n pink 0379-4.jpg|thumb|Novelty PVC flexes]]
+
[[image:Flex blue n pink 0379-4.jpg|right|200px]]
 
Most flex has PVC insulation rated to 70°C.  
 
Most flex has PVC insulation rated to 70°C.  
  
Line 43: Line 41:
  
 
===Arctic===
 
===Arctic===
−
[[image:Flex org n ylo 378-3.jpg|thumb|Arctic flex & mower flex]]
+
[[image:Flex Arctic 0378-6a.jpg|right|200px]]
  
 
Arctic flex remains flexible at low temperatures, whereas regular PVC stiffens. Arctic flex is used for outoor appliances, eg on building sites. It is rated for use down to -40°C.
 
Arctic flex remains flexible at low temperatures, whereas regular PVC stiffens. Arctic flex is used for outoor appliances, eg on building sites. It is rated for use down to -40°C.
Line 55: Line 53:
  
 
===Cloth===
 
===Cloth===
−
[[image:Flex cloth 381-3.jpg|thumb|Cloth flex]]
+
[[image:Flex cloth 0381-5.jpg|right|200px]]
 
Flexes with a cloth outer have rubber inner insulation. These have a high temperature rated outer surface. They are well known for their use on irons.
 
Flexes with a cloth outer have rubber inner insulation. These have a high temperature rated outer surface. They are well known for their use on irons.
  
Line 62: Line 60:
 
The rubber inner insulation can harden and break at the ends. This is often seen on old cloth flexes. When this occurs the flex can be cut back several inches to reveal healthy flex, and reconnected, if the rest of the flex is still healthy.
 
The rubber inner insulation can harden and break at the ends. This is often seen on old cloth flexes. When this occurs the flex can be cut back several inches to reveal healthy flex, and reconnected, if the rest of the flex is still healthy.
  
−
===Whats it called===
+
===Silicone===
−
the very soft high temp plastic insulation sometimes found on irons.
+
Soft high temp plastic insulation sometimes found on irons. Much more heat resistant than PVC
 +
 
 +
===Hi vis===
 +
[[image:Flex hivis 0378-6b.jpg|right|200px]]
 +
Used with mowers etc, where visibility is important for safety
  
 
===Figure of 8===
 
===Figure of 8===
−
[[image:twin_flex_clear.jpg|200px]]
+
[[image:Figure 8 flex 5709-3.jpg|right|200px]]
 +
[[image:twin_flex_clear-2.jpg|right|200px]]
  
 
Figure of 8 shaped plastic flex was formerly used for low current mains uses. It has a single layer of insulation only, and live conductors are easily exposed by minor damage. It was used in several colours, including black, brown, white and clear.
 
Figure of 8 shaped plastic flex was formerly used for low current mains uses. It has a single layer of insulation only, and live conductors are easily exposed by minor damage. It was used in several colours, including black, brown, white and clear.
Line 101: Line 104:
 
For data on how much 90°C insulation changes current ratings, see [[Cable]]
 
For data on how much 90°C insulation changes current ratings, see [[Cable]]
  
−
==Understanding Harmonised Cable Codes==
 
−
An effort by CENELEC (a European standards committee) to harmonise the classification of flexible cables had lead to a coding system that you will often see used to specify the detailed characteristics of a bit of flex. These designations are often written in the form H05RN-F or H05BN-F etc.
 
−
 
−
The codes break down into three parts:
 
−
 
−
===Part 1 of the Designation===
 
−
 
−
'''Table 1a''' gives you the standards compliance and maximum nominal voltage
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
|  width="321" | '''Conformance to Standards'''
 
−
|-
 
−
| H
 
−
| Cable conforms with the harmonised standards
 
−
|-
 
−
| A
 
−
| Cable conforms with a Recognised National Type, listed in a Supplement to the harmonised standards
 
−
|-
 
−
|}
 
−
 
−
'''Table 1b''' Gives the voltage rating of the cable
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Voltage Rating, Single/3Ph'''
 
−
|-
 
−
| 01
 
−
| >= 100/100V to < 300/300V
 
−
|-
 
−
| 03
 
−
| 300/300V
 
−
|-
 
−
| 05
 
−
| 300/500V
 
−
|-
 
−
| 07
 
−
| 450/750V
 
−
|}
 
−
 
−
===Part 2 of the Designation===
 
−
 
−
'''Table 2a''' gives you the insulating material and the designation of any non metallic sheath.
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Material'''
 
−
|-
 
−
| B
 
−
| Ethylene-propylene rubber (Continuous operation up to 90°C)
 
−
|-
 
−
| G
 
−
| Ethylene-vinyl-acetate
 
−
|-
 
−
| J
 
−
| Glass-fibre braid
 
−
|-
 
−
| M
 
−
| Mineral
 
−
|-
 
−
| N
 
−
| Polychloroprene (or equivalent material)
 
−
|-
 
−
| N2
 
−
| Special polychloroprene compound for covering of welding cables according to HD 22.6
 
−
|-
 
−
| N4
 
−
| Chlorosulfonated polyethylene or chlorinated polyethylene
 
−
|-
 
−
| N8
 
−
| Special water resistant polychloroprene compound
 
−
|-
 
−
| Q
 
−
| Polyurethane
 
−
|-
 
−
| Q4
 
−
| Polyamide
 
−
|-
 
−
| R
 
−
| Ordinary ethylene propylene rubber or equivalent synthetic elastomer for a continuous operating temperature of 60&ordm;C
 
−
|-
 
−
| S
 
−
| Silicone rubber
 
−
|-
 
−
| T
 
−
| Textile braid, impregnated or not, on assembled cores
 
−
|-
 
−
| T6
 
−
| Textile braid, impregnated or not, on individual cores of a multi-core cable
 
−
|-
 
−
| V
 
−
| Ordinary PVC
 
−
|-
 
−
| V2
 
−
| PVC compound for a continuous operating temperature of 90&ordm;C
 
−
|-
 
−
| V3
 
−
| PVC compound for cables installed at low temperature
 
−
|-
 
−
| V4
 
−
| Cross-linked PVC
 
−
|-
 
−
| V5
 
−
| Special oil resistant PVC compound
 
−
|-
 
−
| Z
 
−
| Polyolefin-based cross-linked compound having low level of emission of corrosive gases and which is suitable for use in cables which, when burned, have low emission of smoke
 
−
|-
 
−
| Z1
 
−
| Polyolefin-based thermoplastic compound having low level of emission of corrosive gases and which is suitable for use in cables which, when burned, have low emission of smoke
 
−
|}
 
−
 
−
 
−
'''Table 2b''' gives a number of possible metallic coverings:
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Sheath, concentric conductors and screens'''
 
−
|-
 
−
| C
 
−
| Concentric copper conductor
 
−
|-
 
−
| C4
 
−
| Copper screen as braid over the assembled cores
 
−
|}
 
−
 
−
 
−
'''Table 2c''' for some special constructions of components of the cable:
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Sheath, concentric conductors and screens'''
 
−
|-
 
−
| D
 
−
| Strain-bearing element consisting of one or more textile components, placed at the centre of a round cable or distributed inside a flat cable
 
−
|-
 
−
| D5
 
−
| Central heart (non strain-bearing for lift cables only)
 
−
|-
 
−
| D9
 
−
| Strain-bearing element consisting of one or more metallic components, placed at the centre of a round cable or distributed inside a flat cable
 
−
|}
 
−
 
−
 
−
Next, you may get any of the following tacked onto the ends of codes from tables a to c above:
 
−
 
−
'''Table 2d''' Special constructions of whole cable
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Special construction'''
 
−
|-
 
−
| No Symbol
 
−
| Circular construction of cable
 
−
|-
 
−
| H
 
−
| Flat construction of &ldquo;divisible&rdquo; cables and cores, either sheathed or non-sheathed
 
−
|-
 
−
| H2
 
−
| Flat construction of &ldquo;non-divisible&rdquo; cables and cores
 
−
|-
 
−
| H6
 
−
| Flat cable having three or more cores, according to DH 359 or EN 50214
 
−
|-
 
−
| H7
 
−
| Cable having a double layer insulation applied by extrusion
 
−
|-
 
−
| H8
 
−
| Extensible lead
 
−
|}
 
−
 
−
 
−
Next an optional group for specifying the conductor material. This is only required for non copper conductors and will follow a dash.
 
−
 
−
'''Table 2e''' Conductor material
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Conductor material'''
 
−
|-
 
−
| No Symbol
 
−
| Copper
 
−
|-
 
−
| -A
 
−
| Aluminium
 
−
|}
 
−
 
−
 
−
Lastly, Again these follow after a dash (the same one as that used to specify aluminium conductors above if present!)
 
−
 
−
'''Table 2f''' Conductor form
 
−
 
−
(note for cables with two forms of conductor, the specification applies to the phase conductor only)
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Conductor form'''
 
−
|-
 
−
| -D
 
−
| Flexible conductor for use in arc welding cables to HD 22Part 6 (flexibility different from Class 5 of HD 383)
 
−
|-
 
−
| -E
 
−
| Highly flexible conductor for use in arc welding cables to HD22 Part 6 (flexibility different from Class 6 of HD 383)
 
−
|-
 
−
| -F
 
−
| Flexible conductor of a flexible cable or cord (flexibility according to Class 5 of HD 383)
 
−
|-
 
−
| -H
 
−
| Highly flexible conductor of a flexible cable or cord (flexibility according to Class 6 of HD 383)
 
−
|-
 
−
| -K
 
−
| Flexible conductor of a cable for fixed installations (unless otherwise specified, flexibility according to Class 5 of HD 383)
 
−
|-
 
−
| -R
 
−
| Rigid, round conductor, stranded
 
−
|-
 
−
| -U
 
−
| Rigid round conductor, solid
 
−
|-
 
−
| -Y
 
−
| Tinsel conductor (Tinsel conductors are used in flexes for small appliances were normal stranded flex would be likely to fatigue and break - its made with a conductive foil wrapped around a supporting textile or plastic core to provide the tensile strength)
 
−
|}
 
−
 
−
===Part 3 of the Designation===
 
−
 
−
'''Table 3''' Number of cores and the nominal cross sectional area of each core.
 
−
 
−
{|  border="0"
 
−
|  width="60" | '''Symbol'''
 
−
| '''Number and size of conductors'''
 
−
|-
 
−
| (number)
 
−
| Number, n of cores
 
−
|-
 
−
| X
 
−
| Times, where a green/yellow core is not included
 
−
|-
 
−
| G
 
−
| Times, when a green/yellow core is included
 
−
|-
 
−
| (number)
 
−
| Nominal cross-section, s, of conductor in mm&sup2;
 
−
(Note an N after the number of cores indicates the cores are identified by numbers rather than or in addition to colours)
 
−
|-
 
−
| Y
 
−
| For a tinsel conductor where the cross-section is not specified
 
−
|}
 
−
 
−
 
−
===Fitting all the bits together===
 
−
 
−
 
−
{|  frame="box" rules="all" cellpadding="2" border="2" style="text-align: center;"
 
−
| 1
 
−
| 2
 
−
| 3
 
−
| 4
 
−
| 5
 
−
| 6
 
−
| 7
 
−
| 8
 
−
| 9
 
−
| 10
 
−
| 11
 
−
|-
 
−
|  colspan="2" | '''Part 1'''
 
−
|  colspan="6" | '''Part 2'''
 
−
|  colspan="3" | '''Part 3'''
 
−
|-
 
−
| Related<br>standard
 
−
| Rated<br>voltage
 
−
| Insulating<br>material
 
−
| Metallic<br>coverings (2)
 
−
| Non-metallic<br>sheath (2)
 
−
| Constructional<br>components and<br>special constructions
 
−
| Conductor<br>material
 
−
| Conductor<br>forms
 
−
| Number of cores
 
−
| Times
 
−
| Conductor<br>size mm²
 
−
 
−
|-
 
−
|  colspan="11" | Symbols according to tables
 
−
 
−
|-
 
−
| 1a
 
−
| 1b
 
−
| 2a
 
−
| 2b
 
−
| 2a
 
−
| 2c and 2d
 
−
| 2e
 
−
| 2f
 
−
|  colspan="3" | 3
 
−
|-
 
−
| H
 
−
| 01
 
−
| B
 
−
| C
 
−
| B
 
−
| D3
 
−
| No
 
−
| -D
 
−
| 1
 
−
| X
 
−
| Y
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| D5
 
−
| symbol:
 
−
| -E
 
−
| 2
 
−
|
 
−
| 0.5
 
−
|-
 
−
| A
 
−
| 03
 
−
| G
 
−
| C4
 
−
| G
 
−
|
 
−
| copper
 
−
| -F
 
−
| 3
 
−
| G
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| -----
 
−
|
 
−
| -H
 
−
| 4
 
−
|
 
−
| 0.75
 
−
|-
 
−
|
 
−
| 05
 
−
| J
 
−
|
 
−
| J
 
−
| No symbol:
 
−
| -A
 
−
| -K
 
−
| 5
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| circular
 
−
|
 
−
| -R
 
−
| etc
 
−
|
 
−
| 1
 
−
|-
 
−
|
 
−
| 07
 
−
| M
 
−
|
 
−
|
 
−
| construction of
 
−
|
 
−
| -U
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| cable
 
−
|
 
−
| -Y
 
−
|
 
−
|
 
−
| 1.5
 
−
|-
 
−
|
 
−
|
 
−
| N, N4
 
−
|
 
−
| N,N2,N4,N8
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| H
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 2.5
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| Q, Q4
 
−
| H2
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| H6
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 4
 
−
|-
 
−
|
 
−
|
 
−
| R
 
−
|
 
−
| R
 
−
| H7
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| H8
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 6
 
−
|-
 
−
|
 
−
|
 
−
| S
 
−
|
 
−
| S
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 10
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| T, T6
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 16
 
−
|-
 
−
|
 
−
|
 
−
| V, V2,
 
−
|
 
−
| V, V2, V3,
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|-
 
−
|
 
−
|
 
−
| V3, V4
 
−
|
 
−
| V4, V5
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 25
 
−
|-
 
−
|
 
−
|
 
−
| Z, Z1
 
−
|
 
−
| Z, Z1
 
−
|
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| etc
 
−
|}
 
  
−
(1) If two or more symbols listed in the same column need to be used in a given designation, they shall follow each other in their radial sequence starting from the core axis or cable axis.
+
==Laying flat==
 +
PVC flexes have a habit of not laying flat, and bending wherever they were folded in the past. 3 types of flex can avoid this problem:
 +
* silicone
 +
* rubber
 +
* string filled pvc
  
−
(2) The symbols might change their position in the designation with respect to the construction of the cable
 
  
 
==See Also==
 
==See Also==
 
* [[Cables]]
 
* [[Cables]]
 +
* [[Understanding harmonised cable codes]]
 
* [[Low Voltage Wiring]]
 
* [[Low Voltage Wiring]]
 
* [[Special:Allpages|Wiki Contents]]
 
* [[Special:Allpages|Wiki Contents]]
Line 662: Line 122:
  
 
[[Category:Electrical]]
 
[[Category:Electrical]]
 +
[[Category:Basics]]

Latest revision as of 09:38, 10 January 2013

Cavo3x1.5-2.jpg

Flex is stranded electrical wire used for all plug-in mains appliance leads. It is also called flexible cable.

Cable on the other hand is unstranded mains wire not suited to repeated flexing, and is used for fixed installations.


Colour

Cable colours 1179-5.jpg

Current colours:

  • L - brown
  • N - blue
  • E - green/yellow striped

Old colours: (until about 1970)

  • L - red
  • N - black
  • E - green

Colours on US appliance leads:

  • black = live
  • white = neutral

2 Core Flexes

Flex 2 core flat 0835-8.jpg

Flexes are available with 2 or 3 cores (conductors). 2 core flex is only suitable for appliances that don't need an earth connection (marked DoubleInsulated.jpg), and should not be used for extension leads with 3 pin sockets.

2 core flexes are available in both round and oval shape. Oval (flat) uses less material, but any twisting of the flex is visible, whereas it isn't with round.

Multicore

Flex 4 core 0380-5.jpg

Multicore mains flexes are also available for those uncommon tasks requiring more conductors. Non-mains multicores, such as alarm cable, are not suitable for mains use.

Insulation

PVC

Flex blue n pink 0379-4.jpg

Most flex has PVC insulation rated to 70°C.

90°C PVC is also available for use in hot locations, such as for immersion heaters. A higher temp rating also means a given conductor size may carry more current in some (very limited) circumstances. however practically it is not usually possible to take advantage of this increase in capacity since the normal BS 1363 plugs, sockets and flex connection units are not rated for the higher temperature.

Arctic

Flex Arctic 0378-6a.jpg

Arctic flex remains flexible at low temperatures, whereas regular PVC stiffens. Arctic flex is used for outoor appliances, eg on building sites. It is rated for use down to -40°C.

On sites yellow is used for 110v and blue for 240v.

Rubber

TRS (tough rubber sheath) is a flex with greater mechanical strength and damage resistance than PVC. It is used when some degree of rough use can be expected.

VIR is discussed further down.

Cloth

Flex cloth 0381-5.jpg

Flexes with a cloth outer have rubber inner insulation. These have a high temperature rated outer surface. They are well known for their use on irons.

Old cloth insulated flexes are prone to kinking, with the inner rubber insulated wires poking out at the kinks. New cloth insulated flexes have a layer of rubber under the cloth that discourages this from happening.

The rubber inner insulation can harden and break at the ends. This is often seen on old cloth flexes. When this occurs the flex can be cut back several inches to reveal healthy flex, and reconnected, if the rest of the flex is still healthy.

Silicone

Soft high temp plastic insulation sometimes found on irons. Much more heat resistant than PVC

Hi vis

Flex hivis 0378-6b.jpg

Used with mowers etc, where visibility is important for safety

Figure of 8

Figure 8 flex 5709-3.jpg
Twin flex clear-2.jpg

Figure of 8 shaped plastic flex was formerly used for low current mains uses. It has a single layer of insulation only, and live conductors are easily exposed by minor damage. It was used in several colours, including black, brown, white and clear.

Such flex has been unlawful to fit to mains appliances for decades, but is still occasionally seen in use. Today this flex type is used as speaker wire.

Twisted Pair

Twisted pair 0842-7.jpg

2 core cloth & rubber (VIR) twisted mains flex with no outer sheath was once in common use. Most was dark red or brown. This flex has been obsolete for decades, and is rarely seen today. Occasionally its seen on historic electrical goods, and when found is usually in a dangerous condition. Apart from not meeting modern safety requirements, the rubber tends to harden, perish and disintegrate over time, exposing bare live wires. Despite once being in widespread use, it is rarely seen today because it deteriorates badly over time.

Conductor Sizes

Flex conductor size (mm²) Approx max current (PVC insulation)
0.5 3A
0.75 6A
1.0 10A
1.5 15A
2.5 20A
4.0 32A

Note that current carrying capacities are only approximate, and vary with exact construction and materials used for the flex.

For data on how much 90°C insulation changes current ratings, see Cable


Laying flat

PVC flexes have a habit of not laying flat, and bending wherever they were folded in the past. 3 types of flex can avoid this problem:

  • silicone
  • rubber
  • string filled pvc


See Also

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