On Tue, 31 Jan 2017 20:14:55 -0800 (PST), Ed60062
wrote:

I have a vacuum cleaner cord with a cut in the insulation. I could cut the cord short and use with an extension cord but I was wondering if it is acceptable to cut out the bad part and use insulated butt connectors to join the ends and wrap the joint with electrical tape. I've never seen it done so maybe it's unsafe?
Most definitely NOT. Buy a replacement cord (the right one, not an
extention cord) and have it replaced properly. What make and model is
the vacuum.