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Cable Current Carrying Capacity

JD

A very basic question

Current carrying capacity of a cable. My understanding is that if I have a cable rated to 6amps this cable will always only ever be able to take 6amps.

I have been suggested that this rating is only true at 230v and that if I was to drop the voltage the current capacity of the cable may increase. My understanding is this is not related, and even at 12v the cable would still only be rated to 6amps?

Thank you for your help!

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    I'd say the CCC is unrelated to the voltage. You can have 6A at 230V or 6A at 12V. It's the resistance which would be changing to allow more or less current to flow. In either case the 6A would produce the same amount of heat in the cable which is what the CCC is based on. The CCC of the cable is telling you the maximum current that the cable insulation can take safely before it degrades / melts.

    V / I = R.

    230 V / 6 A = 38.3Ω

    If the 6A CCC cable was supplied by 230V and connected to a 38.8Ω load then 6A of current would flow.

    12V / 6A = 2Ω.

    If the 6A CCC cable was supplied by 12V and connected to a 2Ω load then 6A of current would flow.

    I believe the cable should be the same temperature in theory.

    The power used by the two loads would be different (1380W and 72W).

    The CCC will be reduced if any external factors add to the temperature of the cable (rating factors - the installation method, ambient temperature, insulation, grouping etc.).

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