I purchased an additional charger for my SP3 shortly after I received it. One for the office, and one for the road.
Yeah, I'll put some black electrical tape around it but my God, give me a break. Not sure if I am the only one noticing this but can't imagine I am, given I have TWO that are doing the same thing.
I had the same thing happen to mine. When I called Microsoft, they were kind enough to send me a new one, since my Surface was under warranty. Since they did not request that I return the old one, I decided to fix it.
I realized that the heat shrink tubing large enough to fit over the plastic end was not going to shrink enough to cover the wire. I wrapped electrical tape around just the wire to build up a diameter similar to the plastic. Then I slipped the shrink tubing on and heated it with a hair dryer. I did the same to my new one. I now have two power bricks for the price of one.