Guy thank you this sums it up L6 was introduced around 1960 to provide additional current carrying capacity. L2 could take only twin 400mm2 conductors as maximum while L6 could take quad 400mm2. fantastic stuff Anorak,Tizer and Mars bar
Iron Bridge,Shropshire The Iron Bridge designed by Pritchard and made by Abraham Darby's Coalbrookdale works
Pylons shown are part of the 400kv grid system and are double or twin circuits supported by the same pylons. Load carrying capacity per circuit, about 3200 amps in winter but restricted to about 2600 amps at high ambient temperatures normally found in summer because of heat expansion at the higher load results in the circuit catenary to be lower,ie sag.This is to avoid the line to ground minimum distance being reduced which would represent danger to others.
