Subject: Earth leakage testing of a Bradford trolleybus
Location: Thornbury depot
Date: 20-Jun-1971

An essential part of the daily routine of trolleybus operation was a daily earth leakage test. Due to being on rubber tyres no return to earth was guaranteed (unlike on a rail vehicle) and this test ensured that neither passengers nor crew grounded either the positive or negative connection to earth when boarding or alighting.

An original photograph by David Beilby