Code of Practice for the Electricity (Wiring) Regulations - 2009 Edition

Table 15(2)
Maximum Permissible Operating and
Ambient Temperatures of Some Common Cable Insulations
Type of Insulation
Maximum Permissible
Conductor Operating
Temperature (°C)
Maximum Permissible
Ambient Temperature
(°C)
60°C rubber 60 55
General purpose PVC 70 65
Impregnated Paper
(note 1) 80 75
85°C rubber 85 80
Mineral-insulated
(a) 70°C sheath
(b) 105°C sheath
(note 2)
Thermosetting (XLPE)
(note 3)
70
105
65
95
90 85
150°C rubber 150 145
Glass fibre with 185°C
varnish
185 175
Notes: (1) Applicable only to cables of 600/1000V voltage grade.
(2) For mineral insulated cables that are sheathed with PVC, the
values for general purpose PVC are applicable. Otherwise, the
values shown for mineral insulated cables relate only to
terminations; elsewhere the temperature of the cable should not
exceed 250°C.
(3) XLPE means cross-linked polyethylene.
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