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What is the insulation level of a cable marked MV-90/175mils?

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    Jun 2014

    What is the insulation level of a cable marked MV-90/175mils?

    I incorrectly answered the following question. Can someone explain to me what the cable markings mean and provide a link? From reading online it looks like the marking means a medium voltage cable with a normal temperature rating of 90 degrees and an insulation thickness is 175mils. Is the insulation percentage a certain value since the cable is medium voltage? i.e. for MV anything above say 100mils is 100%, anything above 200mils is 133% and anything above 300 mils is 175%?

    What is the insulation level of a cable marked MV-90/175mils?
    Correct Answer: 100%


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  3. Jay Knight is offline
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    For medium voltage cables, insulation levels greater than 100% are intended to provide an additional safety factor for the un-faulted phase conductors in the event of a fault on one phase in a three phase system.

    Insulation thickness’ for medium voltage cables can be obtained from ICEA standards. Check out this link for more information:


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  5. SecondGen's Avatar
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    Cable Insulation Thickness for Various Levels

    The specified insulation thickness for each insulation level is similar among various industry standards. The thickness varies with insulation level, generally becoming thicker as the insulation level increases.

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    Typical insulation thicknesses for many medium-voltage cables are shown in Table 1. Specific insulation thicknesses for voltage ratings up through 46 kV and various conductor sizes are given in National Electrical Manufacturers Association (NEMA), Insulated Cable Engineers Association (ICEA), Underwriters Laboratories (UL), Canadian Standards Association (CSA) and National Fire Protection Association (NFPA) publications.



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