RADIO AND SHOCKS.

New Zealand Herald, Volume LXVIII, Issue 20898, 13 June 1931, Page 10

RADIO AND SHOCKS.

ELECTRICITY DISCHARGE. WATER PIPES AS EARTHS. Discussing the incident reported from Takapuna yesterday regarding, electric shocks received by householders from a water pipe, Mr. Lloyd Mandeno, consulting engineer, said the trouble apparently [ was duo in tho first place to a defect in the insulation of tho wireless set. . This defect would allow current to pass into tho water pipe, and in normal circumstances tho discharge of current would be great enough to blow tho safety fuses in tho house and so automatically disconnect tho supply and obviate any further danger. For this to happen, however, tho water pipo must make good electrical connection with the ground. In the vicinity of Auckland there was, as a rule, usually no difficulty in obtaining this good connection, so incidents of the sort reported were not often met with. But in other districts, more particularly where tho soil is of a pumicious or gravelly nature, difficulty was often experienced. Mr. Mandeno said ho had found that special care was needed in districts where tho water pipes were made of steel and had on them a thick protoctivo coating of bitumen. In such cases the pipo joints usually mado very poor electrical connection, and it was well to remember that water mains of that typo of construction wero quite unreliable for earthing purposes. But in such cases means were availablo to limit tho pressure so as to prevent dangerous shocks being obtained off tlio pipes. Mr. 11. Parsons, of Ilauraki Road, Takapuna, writes: —l desire to make it clear that tho electric radio receiver itself was in no way involved in the phenomena experienced, tho cause actually lying in a defective ground connection. It is clear, ho says, that the shocks sustained would havo beon experienced no matter whether a radio or an iron or radiator had been plugged into the power socket.