ELECTRICAL CAUSE

Gisborne Herald, Volume LXXV, Issue 22618, 22 April 1948, Page 6

ELECTRICAL CAUSE

BALLANTYNE'S FIRE “LACK OF EARTHING” MORE EXPERT EVIDENCE (P.A.) CHRISTCHURCH, April 22. “Lack of earthing was an essential point in causing this fire. If it had been properly earthed, I doubt whether the fire could have happened,” said Edgar Theodore Salversen, principal of a firm of electrical engineers, to the royal commission inquiring into Ballantyne s fire. Salvesen, who was called as a witness by counsel for Bnllantyne’s, said there was no earth wire to the main cable at the circuit breaker. "Unworkmanlike Installation” “The whole installation, apart from the cable which was a good one, was put in in a most unworkmanlike manner and in manv respects did not comply with the regulations.” he continued. "As an electrician, 1 am sorry to say this.” Witness said he considered that the fault occurred on the sr roly side of the fuse- panel and rejected the theory that current escaped through defective joints in the conductor. He believed that a piece of sheet metal inadvertently put on top of the fuse panel had gradually through the years shifted until it came into contact with a live stud at the rear of the panel resulting in the whole box being electrically charged. The fault current could have taken alternative routes to the cable armouring once the metal box became charged. The routes were: Through the conductors to the armouring clamp. 2- Vertically up to the side of the cable end box. ,2. To the cable end box directly. „ Wiring Explained The cable end box was in contact with a clamp on a cable armouring and through the last two routes the fault current was taken to the armouring, and then to the third "1” bearer. “Electricity will try all it can to reach earth 'and take advantage of the best oath offering.” witness said. Weld marks, which would be found on the third “I” bearer definitely indicated electrical contact between the armour and the “I” bearer. The fault current would cause heat in the armour. Witness said he fn-mlv believed that heating took place. Heating of value of -100 or 420 amps would produce vapourising of bituminous mixture in the serving round the armour. He mentioned three alternatives whereby the conduit coidd become red hot, causing ignition o r iv>