A.Anand Srinivasan,
I don't know what you mean by "guard signal", but the other information is contained in cable manufacturers data sheets. Go to their web sites. For example, www.belden.com. Leakage current is not specified, but insulation resistance and capacitance per foot is.
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A guard signal is not a cable parameter, but is a technique whereby the shield is driven from an isolated source that duplicates the voltage on the inner conductor. This eliminates current due to capacitive coupling, because the voltage between the inner conductor and the shield is zero. The shield still works as a shield, because the source impedance of the guard driver is designed to be very low.
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Regards,
Kral