I recently purchased a home in Florida built in 1978, in which I found some "home improvement" projects that need redoing (excessive loads on single circuit breakers, lack of junction boxes, etc.). Upon opening the load center I found that most of 120V circuits are wired with 14GA 3-conductor wire fed from single pole 20A circuit breakers. This does not seem right to me, because the common has the potential of carrying 40A, not to mention that the hot legs do not share a double pole breaker.

I am pretty sure that this is code violation now, but does anyone know if this was a code violation at the time this house was built (1978).

This would be an improper application of electrical technology from the first days of Edison introducing the three wire concept.
Yes! it was a code violation in all the years of publication, of any code.
Connect the 14 guage wire to 15 amp breakers, make sure the black and red conductor of each cable is on opposite buss connections at the panel.
The 15 amp breakers can be single pole, in most cases, if supplying outlets and lighting.

[This message has been edited by Bennie R. Palmer (edited 03-22-2001).]