Bsi bs 2e 21 1957 (2000)

BRITISH STANDARD OBSOLESCENT MARCH 1977 BS 2E 21 1957 Incorporating Amendment Nos 1, 2, 3 and 4 Pren type electric cables for aircraft NOTE The current ratings quoted in this British Standard apply on[.]

Pren type electric

NOT The cur ent ratings quoted in this BritishStan ard a ply only when the ca les are used in

air raft, an are nominal v lues.Actual ratings a pro riate to v arious con itions of instalation in

air raft are giv n in Section J of British Civil Airworthines Re uirements

U C 6 1.3 5.2:6 9.1 0 6

This BritishStan ard, ha ing

b en a prov ed b the Air raft

In ustry Stan ards

Commite ,an en ored b

theChairman ofthe

Engine ringDivisional Cou cil,

was published u der the

authorityof the General

Cou cilofthe Institution on

2 Decemb r1 5

© BSI0 -2 0

The folowing BSI references

relate to work on this stan ard:—

Commite reference AC / 6

Draft for comment CW (ACE)9 2

ISBN 0 5 0 3 5 3 7

This rev ision of BSE2 has be n prep red to bring the specification up to d te

in the lg ht of cur ent practice an of ex erience g ained in working to the fir t

is ue, publ shed in Nov ember19 2 The princip l chang es are:—

a) the introd uction of Duprensheathrou d6 ca le;

b) the mod ification of the construction of Septopren, Septoprenmet and

Septoprensheath ca les to consist of sev en cores laid up arou d a central

dummy core, and to av oid confusion with ca les in the prev ious is ue of this

stand rd, the a d ition of the sufix “ larg e” to the names of these ca les;

c) the introduction of Sextoprensheath6 and Nonoprensheath6 ca les;

d) the deletion of reference to Uniflex ren3 ca le and the introd uction of a

Uniflex ren6 ca le, coloured black;

e) the amendment of the v alues required for the phy sical properties of the

poly chloroprene compou d insulation and sheath;

f) the introd uction of a req uirement for the printing of the let er “AL” in

a d ition to the cur ent rating on aluminium ca les

A British Stand rd do s not purport to include al the neces ary prov isions of

a contract User of British Stand ard s are responsible for their cor ect

a pl cation

Compl anc with a British Standard does not of itselfconfer imm unity

f om leg al o l g ations

Sum m ary of pag es

This d ocument comprises a f ont cov er, an insid e font cov er, p g esi andi ,

p g es1 to1 and a b ck cov er

This stand rd has be n upd ated ( se copy rig ht d ate) and ma hav e had

amend ments incorporated This wi l be indicated in the amendment ta le on

the inside f ont cov er

Am endm ents is ued sinc publ cation

Amd No Date of is ue Comments

19 6

19 8

Foreword Inside font cov er

Section 1 Req uirements

Section 2 Tests

Ta le 3 — Detais of tripren, quinpren and septoprenlarg e ca les 8

Ta le 5 — Detais of triprenmet, q uinprenmet and septoprenmetlarg e

Ta le 8 — Colour of celulose acetate marker thread for the

Ta le 13 — Phy sical properties of poly chloroprene compou d

1 Scope

This BritishStand rd specifies the req uirements

for “ Pren” ty pe ca les for air raft wiring of cir uits

where the potential betwe n conductor , or betwe n

a conductor and metal braid or the air raft structure

do s not exce d6 0v olts ( r.m.s.) in v oltag e

and1 6 0c/s in f eq uency ; also where any

combination of ambient temperature and conductor

cur ent for contin ous serv ice d oes not produce a

sta i iz d cond uctor temperature in exces of9 °C

These ca les are suita le for fixed wiring in air raft

when low temperatures( –7 °C) are encou tered,

but are not suita le for sev ere flexing below–4 °C

The ca les d o not sup ort combustion but they

should not be reg arded as comply ing with the

requirements of BSG10 , “ Genera l requirements

fr el ectrica l equipment a nd ind ica ting instruments

fr a ircra ft , in reg ard to fire resistance

The ca les are u suita le for use without a d itional

protection in areas where ester-b sed fluid s are

present

The g eneric name “Pren” shal be a pl ed only to

ca les cov ered b this BritishStand rd and

comply ing with al requirements of the

specification

The stand rd includes the fol owing four rang es of

ca les, the complete nomenclature of which is g iv en

in Append ix A:—

a) Pren Ca le with a cop er conductor and an

insulation of g las braid and poly chloroprene

compou d, for sing le core ca les: multicore

ca les hav e an ov eral finish of g las braid and

lacq uer:the cond uctor of the Uniflex ren ca le is

of a braided construction which shal not be on a

string centre

b) Pr ena l Simi ar to the Pren rang e but with a

cond uctor of aluminium instead of cop er

c) Prenmet Simi ar to the Pren rang e but with

the a d ition of a metal braid

d) Prenshea th Multi core Pren ca les sheathed

with a poly chloroprene compou d in place of the

lacq uered g las braid

Section 1 Requirem ents

2 Materia ls

a) Cop er cond uctors a nd wires Cop er cond uctor

an wires shal be in ac ord nce with BS7,

“ R ub er-insul a ted ca bl es a nd fl exibl e cord s fr

el ectric power a nd l ight ng”, as far as a pl ca le

W ires taken fom conductor , but not f om braids,

shal me t the requirements for ma imum tensie

streng th an minimum elong ation at break

specified in Clause2 of this BritishStand rd

b) Al uminium cond uctor s Aluminium wires shal be

hard drawn and, before stranding , shal comply

with the requirements of BS27 1, “ Al uminium

cond uctors in insul a ted ca bl es”, where a plca le

Aluminium wires taken f om the stranded or

bunched cond uctor shal comply with the tensi e

and wra ping test requirements of Clause2 of this

BritishStand rd

c) Gl a ss bra id The fe alkal content of the g las

shal not exce d1 per cent The g las shal be of

such finenes that the finished ca le compl es with

al the test req uirements of this BritishStand ard

d) Pol ychl oroprene compou d The poly chloroprene

compou d shal be of such a q ualty that the

finished ca le comples with al the test

requirements of this BritishStand ard

e) La cquer The lacq uer shal consist of a

non- nflamma le, heat-, oi -, an water-resistant

compou d

a) Genera l

i Cond uctor The conductor shal be braided,

bu ched, stranded or rope strand ed , as specified

It shal consist of tinned annealed cop er wires

comply ing with the requirements of Clause2a),

or of hard drawn aluminium wires comply ing

with the req uirements of Clause2b) Joints in

the sing le cop er wires shal be braz d or

soldered but the complete cond uctor shal not be

joined In the case of aluminium and braided

cop er cond uctor the ends of the wires ma be

tucked into the conductor The conductor of the

Uniflex ren ca le shal be of a braided

construction which shal not be on a string centre

Ta le 1 and Ta le 2 state the n mber and

diameter of indiv idual wires and the formation

to be used for the complete cond uctor

There shal be no kin s or other ir eg ularities in

the cond uctor

i ) Compl ete ca bl e The insulation ad jacent to the

conductor shal consist of a g las braid A

poly chloroprene compound, the colour of which

shal be in ac ord ance with Clause5, shal be

a pled ov er the g las braid to the dimensions

g iv en in Ta le 1 and Ta le 2.The insulation shal

be of u iform cir ular c os -section throug hout

the leng th of the ca le and the conductor shal be

ev enly centred in the insulation

The insulation shal not be lo se, but it shal be

pos ible to strip the complete insulation, leav ing

the conductor in a condition suficiently clean to

permit satis actory con ection to terminations

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The rad ial thick es at any point in the wal of

the poly chloroprene compou d shal be not les

than the v alues g iv en in Ta le 1 and Ta le 2

Cur ent rating s shal be identified b the method

specified in Clause5

b) Unipr en ca bl es The ca les shal consist of sing le

cor es comply ing with the requirements of

Clauses2a),2c),2 d) and3 a).The poly chloroprene

compou d insulation shal be coloured and marked

as req uired in Clause5

c) Mul ti-core ca bl es Multi core ca les shal be

coloured as stated in Clause5 and Ta le 7: they

shal be cir ular Septoprenlarg e ca le shal consist

of sev en cores laid up arou d a central dummy core

The laid -up cores shal be cov ered with a g las

braid coated with a non-nflamma le,

heat-, oi -, an water-resistant lacquer coloured in

ac ord nce with Clause5 I fi er are used to

prov ide a g ood sha e they shal be of

poly chloroprene compou d sup orted , if desired, b

a thin texti e threa

It shal be pos ible to strip the g las braid and

lacq uer f om the cores without d mag e to the

lat er

The overal dimensions of the ca les shal comply

with the v alues g iv en in Ta le 3

d) Prena l ca bl es The ca les shal consist of sing le

cor es comply ing with the requirements of

Clauses2b),2c),2d) and3a) The

poly chloroprene compou d shal be coloured and

marked as specified in Clause5

e) Prenmet ca bl es The ca les shal consist of Pren

ca les to which has be n ad ded a metal braid

Sing le-core ca les shal consist of Unipren ty pe

ca le to which a metal braid has be n a pl ed

Multi core ca le shal be constructed b metal

braiding a multicore Pren ca le

Tin ed cop er wires, as specified in Clause2a),

shal be used to form the ov eral metal braid The

braid shal be close fit ing , but wherev er the ca le

is cut it shal be pos ible to sld e the metal braid

b ck b han a distance of4in in a leng th of2 ft,

one end of the ca le being clamped The braid shal

subseq uently be ca a le of being returned to

within1in of its orig inal position

W here breaks in the indiv id ual wires oc ur, the

end s shal be sold ered or tucked out of the braid

and there shal be not more than one such break in

any1 in leng th of ca le

W here renewal of spindles is neces ary , the end s

shal be tucked out of the braid, and there shal not

be more than one spind le renewal in

any1 - n leng th of ca le

There shal be no joints in the complete braid

The diameter of wire used shal be as stated in

Ta le 4 The n mber of spindles an ends per

spindle shal be such as to ensure that the fi lng

factor is not les than0.7 The la factor shal not

ex ce d3 The formulae to be used for the

calculation of the a ov e d etais are g iv en in

Ap end ix B

f) Pr enshea th ca bl es The ca les shal consist of

cores of the multi pren rang e and shal be sheathed

ov eral with a poly chloroprene compou d of the

thick es specified in Ta le 6 The sheath shal be

coloured as stated in Clause5 an shal not be lo se

but it shal be pos ible to remov e it f om the cores

without d mag ing them

I fi ler are used to prov id e a g ood sha e, they shal

be of poly chloroprene compound , sup orted, if

d esired, b a thin textie threa

The ov eral dimensions of the ca le shal comply

with the v alues g iv en in Ta le 6

Prensheath ca les shal be cir ular, an shal

consist of a propriate cores coloured as specified in

Ta le 7 Sextoprensheath an

Septoprensheathlarg e ca le shal consist of cores

laid up arou d a central d ummy core

Nonoprensheath ca le shal consist of two cores

twisted tog ether with sev en cores arou d them

4 Fastnes ofcolours ofca bles

All colour shal be fast to l g ht an moisture The

materials used shal be ca a le of retaining their

colour after storag e for long period s in the tropic

5 Current ra ting identification

The nominal cur ent rating of Unipren ca les up to

and including the1 ampere siz shal be indicated

b colouring of the poly chloroprene compou d as

fol ows:—

Unipren ca les of18 ampere siz and ov er shal

hav e the poly chloroprene compou d coloured blue

and the nominal cur ent rating shal be ind icated b

n merals permanently and leg ibly printed

Prefera ly ,the horiz ntal a is of the fig ures should

be p ral el to the a is of the ca le ( se Fig ure 1) The

printing , which shal be black, shal be repeated at

interv als of not more than6in The heig ht of the

n merals shal be a proximately two-third s the

ma imum ov eral diameter of the core for siz s up to

and including10 amperes and the siz of n meral

used for the10 ampere ca le shal be used for al

ca les a ov e this siz

Uniflex ren 6black

Uniprenal ca les shal hav e the poly chloroprene

compou d coloured y el ow and the nominal cur ent

rating shal be indicated b n merals in the same

wa as for the Uniprenal and larg er ca les In

ad dition the let er “ AL” shal ac omp ny the

n meral, prefera ly as a sufix ( se Fig ure 1)

Multi pren, multi prenmet an multiprensheath

ca les shal hav e the lacquer or poly chloroprene

compou d cov er coloured as folows:—

The colour of the ind iv idual cores in multi core

ca les shal be in ac ord ance with Ta le 7, and the

blue core in18 ampere ca les and a ov e shal be

printed with the cur ent rating as for Unipren

ca les

I desired b the ca le maker, one bob in of coloured

cot on or g las thread ma be incorporated in the

g las braid a jacent to the conductor to as ist the

ca le maker during the production of cores The

colour of this threa when used shal be red

for4ampere cores, blue for6 ampere cores, brown

for9 ampere cores and yel ow for1 ampere cores

W here the poly chloroprene compou d is a pled in

more than one lay er, the outer lay er only ne d be

coloured

6 Identification ofm anufacturer and

year ofm anufacture

The manufacturer shal not mark the ca le itself

with his name an a dres , but a marker threa or

threa s of cot on or other material insoluble in

acetone shal be used, the colour being in

ac ord ance with the cur ent BritishStand ards

Institution reg ister of colour of man facturer ’

id entification thread s for electric ca les and cords,

PD23 9

An ad ditional coloured marker thread or threa s

ma e of celulose acetate, or other simiar material

read ily soluble in acetone, shal be included for

id entification of the y ear of man facture of the

ca le This shal be taken as the y ear in which the

v ulcanizing of the insulation is commenced , and the

colour shal be as stated in Ta le 8

The marker thread s shal be placed betwe n the

conductor an the g las braid They shal not be laid

within the conductor

7 Pa cking and label ing ofca ble

Except for Uniflex ren ca le, the leng th of ca le, in

one piece and on a sep rate coi , re l or drum shal

be10 y ards, or as stated in the contract

For Uniflex ren ca le the minimum leng th of one

piece shal be25y ard s an there shal not be more

than thre leng ths on any10 -y ard re l

After testing , the ca le shal hav e the end s sealed to

prev ent the ing res of moisture Each leng th shal

bear a lnen la el g iv ing the fol owing p rticular :—

a) Name of manufacturer

b) Nomenclature of ca le, e.g Unipren4

c) Siz of conductor, e.g 19/.0 6

d) Br itishStand rd n mber and y ear of is ue

e) Date of man facture ( month and y ear)

f) Release reference n mber

g ) Actual leng th in y ards

Section 2 Tests

8 Genera l

Tests shal be ma e to prov e complance with al

requirements of this BritishStand rd It is not

intend ed or recommended that complete tests shal

be ma e on ev ery ca le leng th sup l ed

The man facturer shal , upon req uest, produce

ev idence to the satis action of the pur haser that

ca le of the ty pe to be sup l ed to this

BritishStand ard fulfi s its req uirements

The man facturer shal dis lose to the pur haser

any proposal to introduce constructions or proces es

d ifering fom those used for the ca le submit ed to

ty pe tests, and shal obtain the pur haser’s writ en

a prov al before a ply ing the chang e to production

18ampere ca les and ov er blue

Fig ure 1

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Thre kinds of tests are specified , as folows:—

a) Type te ts ( Clauses9 to2 ) which shal each be

mad e on sep rate specimens fom a sample

selected b the man facturer f om each of the

folowing g roups of ca les, a sample being

reg ard ed as representativ e of al of the siz s of

ca les in its group, prov ided that they are ma e

b the same proces and with the same materials,

within the g roup fom which it is selected :—

Pren ca bl es:

Group10 Unipren4 to1

Group2 Unipren18 to10

Group3 Unipren13 to28

Group4 Uniflex ren6

Group5 Tripren4 to9

Group6 Tripren1 to24

Group7 Quinpren6 an

Septoprenlarg e6

Prena l ca bl es:

Group1 Uniprenal3 to10

Group2 Uniprenal13 to20

Prenmet ca bl es:

Group 1 Uniprenmet4 to1

Group 2 Uniprenmet18 to5

Group 3 Triprenmet4 to24

Group 4 Quinprenmet6 an

Septoprenmetlarg e6

Prenshea th ca bl es:

Group1 Duprensheath6,

Duprensheathrou d6 an

Triprensheath6

Group2 Quinprensheath6 to

Nonoprensheath6

b) Pr od ucton rout ne te ts ( Clauses14 to2 )

which shal be ma e on ev ery leng th of ca le

c) Prod uct on qua l ity te ts ( Clauses 21 to2 )

which shal be mad e on each b tch

of10 0 0y ard s of ca le, or at least once during

each month’s production, whichev er is the les A

b tch of ca le ma consist of diferent siz s and

ty pes but, wherev er pos ible, the sample should

be representativ e of the siz s an ty pes being

produced

Two samples of ca le shal be selected f om the

prod uction b tch, one sample being of the smalest

siz produced Specimens fom each of these

samples shal each be subjected to the tests in

Clauses21 to2 S ould either of the samples fai

on any one of the tests, the tests shal be repeated on

specimens f om four further samples selected at

rand om S ould any one of these samples fai, the

b tch shal be de med not to comply with this

BritishStand rd

For the tests in Clauses9,10, 1 ,12, 21and2 ,the

metal braid on Prenmet ca les shal be remov ed

Type tests only

9 Resistance to fluids

The test specimen shal be bent into a sing le lo p,

the internal diameter of which is six times the

ma imum specified d iameter of the complete ca le

The specimen shal be immer ed in the fluids lsted

in Ta le 9 an maintained at the stated

temperature for not les than24hour , with the

ca le ends out of the lq uid

At the conclusion of this period the ca le shal be

remov ed f om the fluid and shal be wou d on a

mandrel, the diameter of which is thre times the

ma imum specified diameter of the complete ca le

The specimen shal be kept on the mandrel for one

min te and then u wou d The ca le shal show no

sig ns,to normal v ision, of splt ing or c acking , an

the chang e in diameter shal not exce d the v alue

g iv en in Ta le 9 During , and at the conclusion of

the test, the colour of the ca le shal not be

a precia ly afected

10 Ag eing in air

A specimen,at least6in long , shal be placed in an

air ov en, maintained contin ously at10 ±2°C for

sev en d y s At the conclusion ofthis ag eing period,

the sample shal be remov ed fom the ov en and kept

for fifte n min tes at a temperature of20±5°C

The specimen shal then be wou d on a mandrel,the

diameter of which is four times the ma imum

specified dimension of the complete ca le After one

min te on the mandrel the specimen shal be

u wou d and it shal show no undue d eterioration

11 Low tem pera ture test

In the folowing tests the mandrels shal be of metal

and shal be al owed to co l to the specified

temperature with the ca le

A specimen of the ca le, at least1 in.long , shal be

stored in air at–3 ±2°C for a period of six hour ,

immediately after which it shal be wou d on a

mandrel, the diameter of which is ten times the

ma imum specified d iameter of the ca le The rate

of wind ing shal be a proximately one conv olution

per second After one min te on the mandrel, the

ca le shal not show, to normal v ision, any sig ns of

c acking

Multi core Pren and multi core Prenmet ca les

shal be tested at a temperature of–15±2°C

NOT Ca les fulfiling the re uirements of this test wil

withstan a temp rature of–7 °C when instaled in airraft

an not subject to mov ement

12 Flexibi ity

A specimen of the complete ca le shal be wou d on

a mand rel at ro m temperature, u d er a tensi e load

of5lb for ca les up to and includ ing0.5in in

d iameter, or10lb for ca les ov er0.5in in d iameter,

into a close helx, the internal diameter of which is

thre times the ma imum specified diameter of the

ca le The complete test shal comprise fiv e test

cy cles, each cy cle consisting of the winding of the

ca le on to the mand rel, u winding and re-winding

in the rev er e direction, so that the sur ace of the

ca le on the insid e of the helx during the fir t

winding is on the outside of the helx upon

re-wind ing No p rt of the ca le shal show sig ns of

d amag e after the test

13 Volta g e test

At the conclusion of each of the tests specified in

Clauses 9, 10,1 and12, each specimen shal be

immer ed in water and , whi st so immer ed, shal

withstand a test v oltag e of15 0( r.m.s.), of

wav eform as specified in Clause15, maintained for

one min te, a pl ed betwe n the conductor an the

water For multi core ca les this test shal be mad e

on core taken f om the complete ca le

Type a nd production routine tests

Al ca le shal be checked for complance with the

requirements of this BritishStand rd relating to

construction and d imensions

Al completed ca les shal be ex mined along the

entire leng th for d efectiv e workmanship

15 Voltag e test on core

Except when tested in ac ord nce with Clause17,

al core shal be immer ed in water at ro m

temperature for not les than1 consecutiv e hour :

at the end of that time whist so immer ed it shal

withstand the v oltag e shown in Ta le 10 a pled

betwe n the conductor and the water The v oltag e

shal be a pled g rad ualy an maintained

contin ously for fifte n min tes The reg ulation of

the sup ly for the v oltag e test shal be such as to

maintain the specified v oltag e on the ca le

throug hout the test The peak v alue of the v oltag e

wav e shal be within±5per cent of Æ2 ×r.m.s

v alue and the f equency shal be at any v alue

f om25 to10 c/s

16 Insulation resistance test on core

After the a pl cation of the v oltag e test and whist

the core is sti l immer ed , the insulation resistance

for1 0 0y ards, measured betwe n the cond uctor

and the water after one minute’s electrification with

the v oltag e shown in Ta le 10, shal be not les ,

when cor ected to a temperature of20°C, than the

v alue stated in Ta le 10 The rate of chang e of

a p rent insulation resistance during the one

min te’s electrification shal be stead y

17 Spark test on core

I desired b the man facturer, a sp rk test in

ac ord nce with BS7 on al d ry cores and a v oltag e

and insulation resistance test on5 per cent of al the

core ma be mad e instea of a v oltag e and

insulation resistance test on al core The sp rk test

v oltag e shal be in ac ord nce with Ta le 1 and the

v oltag e an insulation resistance tests in

ac ord nce with Clauses 15 and16

18 Voltag e test on com pleted cable

a) Mul ti-core type onl y, other tha n meta l bra id ed

All completed ca les shal withstand30 0v olts

r.m.s a pl ed for one min te betwe n each

conductor and the remaind er con ected tog ether

The ca le shal be tested in a dry state an the

v oltag e sup ly shal be as specified in Clause15

b) Meta l bra id ed ca bl es Multi core ca les, before

metal braiding , shal be tested in ac ord nce with

Clause18a) After braiding , al ca les, including

sing le-core ca les, shal withstand1 5 0v olts

r.m.s a pl ed for one min te betwe n al the

conductor con ected tog ether and the metal braid

© BSI 0 -2 0

19 Conductor resistance test on

com pleted cable

The cond uctor resistance shal be measured on al

completed ca le and the resistance of a sing le

conductor per1 0 0y ard s of the finished ca le shal

not exce d the v alue stated in Ta le 1 an Ta le 2

( for cop er an aluminium respectiv ely ) at the

specified temperature

The resistance of multi core ca les in completed

form shal not exce d the v alue specified for the

cor esponding siz of sing le core ca le b more

than5per cent

20 Identifica tion, pa cking and

Each coi, re l or drum of completed ca le shal

satis y the requirements of Clauses6 and7 for

id entification of manufacturer an y ear of

man facture and for p cking and la el ing

Type and production qual ty tests

21 Non- inflam m a bi ity test

The n mber of specimens to be tested is stated in

Ta le 1 Al specimens shal be cut consecutiv ely

f om the same coi

Each specimen of ca le shal be sup orted at an

ang le of4 ° in a draug ht-fe chamber, an the

hot est point of a v ertical3- n non- uminous

flame( ) in Bu sen burner) with a blue cone1in

hig h shal be ar ang ed to imping e on the central

portion of the specimen for the time specified in

Ta le 1 After the sour e of the flame has be n

remov ed, the ca le shal me t the folowing

req uirements:—

a) The ca le shal cease to burn within ten

seconds

b) The total leng th burned or char ed shal not

exce d3in

22 Mechanica l streng th ofconductors

a) Cond uctor s other tha n fr om Unifl expren ca bl e

i The tensie streng th of each cop er or

aluminium wire taken fom the finished ca le,

and the minimum elong ation of each cop er wire

taken f om the finished ca le shal conform to the

v alues g iv en in Ta le 1 For these tests the

g aug e leng th on the test specimen shal be10in

and the clamps shal be sep rated at a rate not

exce ding fiv e inches per min te The tensi e

streng th shal be calculated on the orig inal c os

-sectional area of the wire

i Aluminium wires shal not break when

subjected to the fol owing tests:—

W ra the wire rou d a wire of its own diameter

to form a close hel x of eig ht turns Unwra six

turns and ag ain closely re-wra them in the

same direction as the fir t wra ping

b) Cond uctors from Unifl expren ca bl e The

insulation shal be remov ed carefuly f om

a1 -n leng th of Uniflex ren ca le and the

conductor as a whole shal be subjected to a tensie

test to determine its breaking loa , care being taken

to av oid local concentrations of stres at any clamps

I this load is3 lb or les the cond uctor shal be

reg arded as satis actory ; if the loa is more

than32lb the conductor shal be reg ard ed as not

me ting the req uirements of this specification I the

loa is more than3 lb but not more than32lb the

d iameter of the ind ivid ual wires of the braid forming

the cond uctor shal be measured : then prov ided the

a p rent breaking stres in the conductor ( breaking

load div id ed b 4 times the av erag e measured area

of each of the conductor wires) is not more

than3 0 0lb/sq in the conductor shal be

reg ard ed as satis actory

23 Tinning test

The tin ing of cop er cond uctor shal be tested for

complance with the req uirements of BS7, as far as

a pl ca le

24 Physica l properties ofinsula tion

and shea th

The insulation and sheath shal be tested for

complance with the properties lsted in Ta le 13