Depth at Water Main - 3'6", Depth at Gate Box, 4'. From the Gate Box to my basement was more than 4'.Tuesday saw the road repair, so what really happened?
Remember the 5"x8" card from 1917?
Depth at Water Main - 3'6", Depth at Gate Box, 4'. From the Gate Box to my basement was more than 4'.
The Frost Line was at 3'.
The pipe from the Main to the Gate Box was at the 3' level, according to the contractors, indicating that the freeze first started in the City's portion of the pipe. This is consistant with the fact that I could not clear it from my side, even with 200 amps running from my house to the Gate Box.
What Broke?
The card also indicates that the Length in Street was 23' Iron 9' Copper, hence there was a connection. This connection from the Iron pipe to the Copper pipe can be seen below.
Connections are held together by a "compression fitting" which contains rubber. When the 200 amps was passed through from my Gate Box, out to the Main, and to the neighbor's Gate Box, it heated up this coupling more than other, lower resistance, portions of the pipe. This burned out the rubber, and split this coupler. The contractors indicated that there were other problems with the line.
What's Left?
The new copper pipe currently goes to a new Gate Box, and a new 8" copper pipe then goes to a new compression fitting to my old iron (lead lined) pipe. I think the city wanted this architecture so that next time I put 200 amps through the pipe it will burn out on my side of the Gate Box. The plumber told me that my pipe was in as good a shape as he has seen for these old houses.
So I believe it will last at least into next winter. I'll probably replace it this spring or summer, as an improvement to the house, to be realized when we sell.
-- Glen