Dangerous Mains Leads! - Safety warning about dangerous mains cables - have you had this problem?
John Woodgate has advised that he has recently received a report from a normally reliable source that a large number of potentially dangerous mains leads have been released onto world markets. The existence of these defective leads was first reported in Australia. The leads have an IEC 60320 connector at one end and one of various different mains plugs at the other end. Not surprisingly, the leads carry apparently convincing approval marks. The danger comes from the fact that the conductors are not only very thin, but also of abnormally high resistance. As a result, not only is the current-carrying capacity (for an acceptable temperature rise) limited, but the protective conductor resistance is much too high - about 0.5 Ohms for a3 m lead has been reported. When used for a computer, monitor or printer, such leads would not overheat, but the earthing is not satisfactory, and this would not normally be detected until, possibly, too late. If such a mains lead were transferred to feed a higher-current load, within its apparent current rating, it would quite possibly burn up.
We have not yet seen any press reports about this problem, but the report received by John Woodgate said that one large manufacturer had recalled suspect leads. It is strongly recommended that vigilance should be maintained, implemented at the practical level by d.c. resistance measurement checks on incoming mains leads.
The Standards Office is keen to hear from any member who has found this problem. Please contact us.
(This warning first appeared in the September 2002 issue of Standards News, issue 124.)