EPDM or Silicone tubing for secondary insulation against arcing?

[RnDman]

I need to prevent high voltage arcing (+5000vdc and -1600vdc) between existing short wires and/or their terminating electrodes. I would like to find a hollow insulation or tubing (of about 5/64-in./0.078-in. ID) that is made of silicone, or preferably EPDM, that can be slipped over the insulation of the wire to increase its dielectric strength. I need to seek such a solution at this time, and possibly later, the wire design can be changed to a stock EPDM-insulated wire, if I can also find a supplier. I don't know the guage of the stranded wire, but it is 14-guage or less.