June 1962, the class suffered traction motor insulation trouble which meant the motors had to be re-wound. 302312 was used as a test bed for silicon rectifier technology and a Brentford transformer from 1962 to 1964, then used to test thyristor control equipment until 1972, becoming the first electric train so fitted in the UK. Unit 302 244 was involved in an accident in 1972 with a lorry at a level crossing at Low Street railway station in Tilbury, after which it was decided to scrap the leading carriage, BDTC 75292. This was replaced with DTSO 77164, originally belonging to a Manchester-Bury Line Class 504. It remained like this until May 1983 when it acquired a spare BDTC, 75298, from withdrawn unit 302250. In 1987-88, 6 units were short formed with the removal of the trailer composite (TCsoL) and based at Ilford EMD for work on the GE lines. Following the privatisation of British Rail, ownership of the last 30 units passed to Eversholt Rail Group with all units being leased by LTS Rail. The run-down of class 302s started in 1984 with the majority being phased out when Class 310 where introduced on to the LT&S in 1988 with last 30 units being withdrawn by 1998 with the introduction of Class 317 in 1997 and with extra Class 312 in 1998. Electrical equipment Electrical equipment was supplied by English Electric with the majority of equipment being interchangeable with Class 308 units. Electrically there were three main systems, Control which operated at 110 volts DC, provided by nickel iron alkaline secondary cells, auxiliary 250 volts AC from the tertiary winding of the main transformer which provided power to the battery charger which was also rectified to power the main compressor, and finally power circuits derived from secondary winding of the main transformer at 1,500 volts AC. The primary winding of the transformer was designed to operate on either 6.25 kV or 25 kV with voltage sensing equipment fitted to ensure the correct arrangement of primary windings for a given voltage. An incorrect voltage selection device was fitted to both the Class 302 and Class 308 stock so that if the primary winding was connected for 6.25 kV when supplied with 25 kV the air blast circuit breaker manufactured by Brown Boveri would remain closed but the pantograph would be lowered. Should this happen the transformer would require changing and overhaul