ELECTRICAL PLUGS

Evening Post, Volume CXXVI, Issue 63, 12 September 1938, Page 10

ELECTRICAL PLUGS

EARTHING PRACTICE

OPINION DIVIDED

The debatable question whether all three-pin plugs should be earthed, and whether all electrical appliances to be used with them should be supplied with three-core cord was discussed at the Electrical Supply Engineers' conference today. "No subject has received more consideration than the common plug and socket as used in domestic installations," the advisory committee's report stated. "The general principles involved in earthing are simple:—(a) In situa-. tions where, by reason of the presence of earthed metal, conducting surfaces or dampness, breakdown of the insulation of an appliance would involve a risk, the appliance must be earthed, (b) It has to be admitted that hazard is increased by the presence of earths, and it is* therefore inadvisable to introduce an earth into situations, or to earth appliances where, under ordinary circumstances, an earth would not exist and ap-) pliances need not be earthed. "At the same time it is obvious that, for the sake of expediency, plugs for the appliances in any particular domestic installation should be of uniform type. , "We then have the condition that an appliance with a two-core flex, and normally used on an unearthed three-pin socket in a, drawing-room, may be connected to an earthed socket on a range, or an appliance with a three-core flex may be connected to *a non-earthed three-pin socket and used in a washhouse. "The question of whether all threepin sockets should be earthed, and all appliances used with same provided with three-core flex, was referred to members of this association by the Government. Opinions of supply engineers are divided, and it is considered by the advisory committee that the matter should be discussed and a recommendation made." AN EXTRA HAZARD. Mr. J. W. Muir (Palmerston North) said that the matter of the earthing of all appliances needed some consideration. The earthing of an appliance in the drawing-room would introduce a hazard into the room. The hazard was greater in a bathroom than in a drawing-room. He was of opinion that it. was safer not .to earth all appliances. Mr. B. Goldsmith (Taranaki) said that the three-pin plug which was not earthed had a deceptive appearance of safety. A salesman might use such a plug to demonstrate a washing machine, thinking it was safe. Another illustration was the use of a vacuum cleaner on a motor-car, the user taking the cord out of a window. Other speakers were divided in their opinions. It was pointed out that there was no control over departmental stores, and the public bought and used adapters.. Another delegate considered that if three-pin plugs were installed the third pin should be earthed. The trouble would never be obviated till there was some control over the sale of fittings.