Current rating standards 69-30 Part I
Sustained Current Ratings for Paper-Insulated Lead-Sheathed Cables to BS 6480 Part 1 1969 (ac 50 Hz and dc).
This report, which is part 1 of a series, provides current ratings for metric sizes of paper-insulated, lead-sheathed cables to BS 6480. A further part covers plastic-insulated cables. Ratings are given for cables installed direct in the ground, in underground ducts and in air.
Ratings have been calculated in accordance with the formulae recommended by the International Electrotechnical Commission where relevant, for other cases formulas have been taken from ERA reports. The temperature limits on which cable ratings are based have been adopted on the recommendations of British cable manufacturers.
The tabulated ratings for cables laid direct in the ground and in underground ducts correspond to values of soil resistivity and temperature which have been found to be generally representative of conditions in Great Britain. For many installations the tabulated ratings will be applicable without correction.
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