BS EN ISO 13297:2021+A11:2023 ISO 13297:2020+A1:2022


Table A.2— Derating of maximum current rating in Table A.1


Temperature rating of conductor insulation


70 °C


85 °C to 90 °C 105 °C 125 °C 200 °C


Number of conductors bundled 4 to 6


7 to 24 25 or more


Multiply maximum current from Table A.1 by


0,75 0,82 0,86 0,89 1


Multiply maximum amperage from Table A.1 by


0,7 0,6 0,5


NOTE Derating reductions for temperature and bundling are cumulative.


As a guideline: the voltage drop (E) at load, in volts, can be calculated using the following formula: E


=


where S I


NOTE


0 0164 IL S


, ××


is the conductor cross-sectional area, in square millimetres; is the load current, in amperes;


L is the length, in metres, of conductor from the positive power source to the electrical device and back to the negative source connection.


On a 12 V system, an approximation of a 3% drop can be obtained by the following:


S IL= × 20


22


© ISO 2022 – All rights reserved


Distributed by the RYA under licence number 2020ET001 © BSI


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