I very rarely use split bolts anymore, but here is how I insulated them. First wrap with varnish cambrick, glue side up. Then turn and wrap with glue side down. The reason is then if you have to cut off the insulation, it will come off in one peice. Next scotch elect. tape, then the fabric tape. Use plenty of each.
Sure am glad they have made life easier for us now. The split bolt still has its place, but very few places. Yours could be one. I am not familiar with "Kupletap".
