Elastomer insulated fire resistant (limited circuit integrity) cables for fixed wiring in ships and on mobile and fixed offshore units

BS 7917:1999 pdf free.Elastomer insulated fire resistant (limited circuit integrity) cables for fixed wiring in ships and on mobile and fixed offshore units – Requirements and test methods.
6.10.1 Material
The outer sheath shall conform to 5.5.
6.10.2 Thickness of outer sheath The thickness of the outer sheath, when determined by taking the average of a number of measurements in accordance with annex C, shall be not less than the value specified itt Tables 6(0 15, as applicable, and the smallest of the measured values shall not fall below the specified value by more than 15% + 0.1 mm.
NOTE Where the outer sheath tills (1w interstices between the units the specified thickness applies at the places where the thickness ol sheath is at it_s minimum.
6.11 Non-standard numbers of pairs, triples or quads
If agreed between the purchaser and the manufacturer, it shall be permissible for cables to he made with numbers of pairs, triples or guads other than those specified in Tables 6 to 15. In such cases, the thicknesses of the insulation and sheath(s) and the diameter of the braid wire (if any) shall be those specified in the relevant table for the cable containing the next higher number of pairs, triples or quads.
6.12 Electrical tests
NOTE The electrical tests are hated in Table 3.
6.12.1 Conductor resistance
The d.c. resistance of each conductor in the finished cable shall be measured in accordance with BS 6360. The results, when corrected to 20°C in accordance with BS 6360 shall conform to that standard.
6.12.2 Voltage test on completed cable
When the completed cable is tested in accordance
annex I) the insulation shall not break down.
6.12.3 Insulation resistance tests
6.12.3.1 Insulation resistance of cores The insulation resistance shall be tueasllre(l immediately after the voltage test specified in 6.12.3 has been applied. When tested in accordance wit Ii E. 1 the calculated insulation resistance constant shall be not less than 2 400 MIkm at 20 °C.
6.12.3.2 lusul& ion resistance bet u’een screens
(,ndiridually screened pair, triple or quad cables)
For cables with individually screened pair, triple or qIla(I corist mclion the insulal ion resistance between screens when tested in accordance with E.2 shall be not less than 1 Mf i-km at (20±5) °C
6.12.3.3 Insulation ?Tustanre sr,v’enCc) to braid !indiidually or collectively screened pair(s), triplefr.) or quadft) cablcs,
For braided cables with individually or collectively screened pairs, triples or quads the insulation resistance between the screens and the braid when tested in accordance with E.3 shall be not less thaii 025 Mfl-km at (20 ±5) °C.
6.13 Non-electrical tests
6.13.1 General
NOTE 1 The non-electrical tests are listed in Table 3.
NOTE 2 In somr te’st, the preparation and prescutation of the test sample ean have a entiral effect on the result ol ilw tests, so it is csiwiiilal that test samples are always prepared carrlully.
Test samples shall be examined for damage before testing. Test samples which have been damaged during preparation shall not he tested.
6.13.2 CompatIbility
When a sample of completed cable is aged in accordance with F.2, the insulation and outer sheath shall conform to the requirements specified in Table 5. hi addition, at the end of the test period in the oven, the blotting paper shall be free of stain.s.
6.14 Tests under flre conditions
6141 VertIcal burning test (single cable) All cables shall he tested in accordance with BS 4066—1 and shall conform to the requirements of that standard.
6.14.2 Test for flame propagation (bunched cables)
All cables shall be tested in accordance with Category A (designation F) of 13S 4066-3:1994, except that the cables, irrespective of conductor sizes, shall be installed in a touching configuration on the front of the ladder not exceeding 3oo mm width, and the perfonitance of the cables shall conform to the requirements of that standard.
6.14.3 Test for smoke emission
The completed type SW 3 and SW 4 cables shall be tested, using the apparatus given in BS 7622-1, in accordance with the test procedure given in BS 7622-2:1993. The cables shall be tested as a flat horizontal unit. The number of cables shall be in accordance with BS 7622-2:1993, 4.2.1. The smoke generated shall not result in transmittance values lower than 60 96.
6.14.4 Corrosire and acid gas emission Each non-metallic element of type SW 2 cables when tested in accordance with BS 6425-1 shall have a level of HCI not greater than 5 96.
Each non-nwtallic elenwnt of type SW 3 and SW 4 cables when tested in accordance with BS 6425-1 shall have a level of HCI not greater than 0.596.
6.14.5 Test for fire resistance (limited circuit integrity)
The test for fire resistance shall be performed in accordance with IEC 331:1970 except that the temperature of the flame shall be as follows.
— For cables with class 2 conductors, the temperature of the flame as measured by the thermocouple shall he (950 ± 50) °C, and those cables which conform to the requirements of IEC 331:1970 shall be designated Fl.
— For cables with class 5 conductors, the temperature of the flame as measured by the thermocouple shall be (750 ± 50) °C, and those cables which conform to (he requirements of IEC 331:1970 shall be designated FO.
7.1 Conductors
The conductors shall be tuuied annealed circular or circular compacted copper conforming
to B.S 6360:1991. Class 2 or class 5 conductors shall be used for conductor sizes of 1 nm and L5 nun2 and cLass 2 shall be used for all other conductor sizes. The conceptual construction of 25, 35. 95, 400 and 500 1111112 conductor sizes shall be 19/1.35 mm. 19/1.53 nun, 37/1.78 mm. 91/2.36 nun and 9112.65 null, respectively.
NOTE 1 (lass 5 Ct)iHIli(’tOFs an’ UI(’lUd4d (0 ud mstaiialion and tI’tflUflatIOII (If Cld)ICS UI (OfltiIWd !q ue’s. ‘fla ww of class 5 conduetorx (Inca (lot imply that iheac vabh’a arc suitable for applications whcrc hwy will 1w subjected In (rrqiwnt or rvwalrd fk’xing (5cc annex II).
NOTE 2 Sec also 7.10.5.
7.2 Insulation
7.2.1 Material
The insulation shall conform to the requirements of BS 7655-1.2:1997, type GP 4 for 60W1 000 V cables and type GP 5 for 1 900i 300 V and 3 300f3 300 V cables.
When necessary in order to meet the performance requirements of this standard, a tape or tapes shall he al)I)lie(l either over the (‘OIBluctOr or over the insulation.
All components shall have halogen acid ga.s emission levels hot excee(hng that specified in 7.10.4 for the relevant cable type.
7.2.2 Application
The insulation shall be applied closely to the con(tuctor or conductor taping by the extrusion process to form a compact and honlogenous layer. It shall be po.ssible to remove the insulation without damage to the insulation itself, the conductor, or the tin coating, if any.
7.2.3 ThIckness
The thickness of the insulation, when determined by taking the average of a number of measurements as described in annex C, shall be not less than the value specified in the appropriate construction table (see Tables 19 to 34) and the smallest of the measured values shall not. fail below the specified valLie by niori’ than 10% + 0.1 mm.
The thickness of any tape(s) over the conductor or over the in.sulation shall not he included in the measurement of the thickness of tile insulation.BS 7917 pdf free download.Elastomer insulated fire resistant (limited circuit integrity) cables for fixed wiring in ships and on mobile and fixed offshore units