I've been reading the Island Line Upgrade thread (re : the Isle of Wight line) in the Infrastructure forum, and a remark was made that it has been quite easy to convert ex-LU stock from fourth to third rail electrification : just a matter of removing the centre shoes and re-routing some power cable.
So I wonder why the fourth rail continues to be used on LU. I understand that it was originally needed because when third rail was tried in early trials (in the Earls Court area around 1900), fuses and light bulbs blew in nearby properties due to earth leakages. Or something like that. Clearly the southern electric and other third rail lines have not had that problem, perhaps because of improved wiring standards (railway and/or domestic). So I wonder why LU still finds the fourth rail necessary, if it is. There would be a fortune in scrap steel and maintenance savings if the trains were converted at their overhauls and the centre rails then progressively removed during track renewals..
So I wonder why the fourth rail continues to be used on LU. I understand that it was originally needed because when third rail was tried in early trials (in the Earls Court area around 1900), fuses and light bulbs blew in nearby properties due to earth leakages. Or something like that. Clearly the southern electric and other third rail lines have not had that problem, perhaps because of improved wiring standards (railway and/or domestic). So I wonder why LU still finds the fourth rail necessary, if it is. There would be a fortune in scrap steel and maintenance savings if the trains were converted at their overhauls and the centre rails then progressively removed during track renewals..