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Appendix 4, section 6.1 equation 6

Former Community Member
Former Community Member

 

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Hi I am working through equation 6 for an ambient temperature of 50 degrees for 1mm 90degC thermoplastic cable (Table 4E2A)

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I get a correction factor of 0.95 for a 2A load. 

Do i divide the mV/A/m by this factor ? 

The text says multiply, but that would mean the resistance decreases with the increase in temperature (or have I got the sum wrong?)

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    Andrew the comment by Sparkingchip is not very complete above about cable temperature ratings.

    A cable that runs through a “hot” area but is terminated in cooler ones can run at 90C in the “hot” area, as long as the terminations to most accessories remain below 70C, their normal rating. Special items can be obtained to run at higher temperatures but they are generally expensive.

    You need to be careful too about the temperature rating of rubber cables, many are rated at 60C, because rubber deteriorates at higher temperatures much faster than PVC or XLPE. Refer to the manufacturer's data. Your description suggests all of these details can be ignored, but at 300m length you will find the voltage drop may be a problem, it all depends on the nature of the load. If a few lights no problem, if motors or appliances a bit of thought may be needed.

     

    Regards

    David CEng etc.

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  • 0

    Andrew the comment by Sparkingchip is not very complete above about cable temperature ratings.

    A cable that runs through a “hot” area but is terminated in cooler ones can run at 90C in the “hot” area, as long as the terminations to most accessories remain below 70C, their normal rating. Special items can be obtained to run at higher temperatures but they are generally expensive.

    You need to be careful too about the temperature rating of rubber cables, many are rated at 60C, because rubber deteriorates at higher temperatures much faster than PVC or XLPE. Refer to the manufacturer's data. Your description suggests all of these details can be ignored, but at 300m length you will find the voltage drop may be a problem, it all depends on the nature of the load. If a few lights no problem, if motors or appliances a bit of thought may be needed.

     

    Regards

    David CEng etc.

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