About the blue electrical tape many legends, stories, jokes, and even anecdotes. The basic idea - a joke: if a thing can not be repaired with tape, so it is not subject to repair at all! :))
And - again, why blue?
There is a lot of versions of this bill, the bulk of them - is that blue dye was the most common and available at the time, so it was made a blue.
Blue insulating tape, however, like other bright colors, very visible, so immediately struck by the place of twists and coils her. If the place lay under the tape and began to burn strongly to bask, blue electrical tape started to get dark, and immediately it became clear that at this point the problem of a twist, and therefore can be quickly, and most importantly all the time correct. On the black tape to observe it would be almost impossible.
But in my opinion, the main reason is different.
Duct tape was invented and released after the war (in 1946) 3M Company ( "Three Em"). First were issued bright colors such as white, yellow, light green, etc... But over time, this highly insulating tape is destroyed by sunlight. Therefore, the company gradually shifted to the production of electrical tape dark, black, blue, etc... They are UV resistant, and destroyed much more slowly under its influence.
After the duct tape came in 40 - 50 years in the Soviet Union started a real "boom conveyor". She pasted all in a row, sealed wounds, cuts; repairing toys, things; They tied up the luggage; and even children are wrapped mittens on their hands, that they would not have lost them while walking.
Since then, and went opinion that blue electrical tape - the most versatile and reliable means to repair and at home.