تيار متردد
Dynamotors were provided in at Town Hall and Lang Park to supply direct current to customers. Alternating current was adopted as the new standard from 1930, although the first AC substation did not come into use until 1935. The AC system was not completed until c. 1958. No new DC customers were accepted after 1935, but the existing supply continued, albeit with mercury-arc rectifiers in later years, until 1985.