Anyone who knows about the electricity that powers our Tube will tell you that if you have an 'earth', then this is something to worry about.
In 'Triangle sidings' on the District Line, there were positive and negative earths in the same area, where there is also bad water seapage. When this happens, something is bound to go 'Bang!'. And it did. Ten track circuits blew. A porcelain pot exploded.
The root of all this? You guessed it. Poor maintenance. The track is Metronet's responsibility. Lucky that trains never carry passengers over this area of track, but this is no excuse for this kind of neglect.