Glyn Garside provided some very good background on house wiring in the U.K.
He posed a couple of questions... > It would be interesting to know if the US approach (low-cost GFI on new > hairdryers) ultimately achieves the same rate of bathroom electrocutions > (all devices, not just dryers) as the more restrictive UK regulations > (no outlets at all). In the USA, hair dryers are now provided with an "Immersion Detection Device." The control circuit is located in the plug. The hair dryer has a sense wire surrounding the live parts. When the dryer is immersed in water, current flows in the sense wire and causes a relay in the plug to open the circuit. Note that this is NOT a GFCI (Ground Fault Circuit Interrupter). The IDD senses fault current flowing in the path created by water displacing the air insulation. The device operates without respect to ground. > heating elements in dishwashers and washing machines. (I don't know if > these actually pose a safety hazard, but my mother reports from London > that since rewiring her house last year with RCCD's throughout, she has > had to replace both these appliances although they otherwise worked > fine, because they sometimes tripped the RCCD during the heating cycle. Older electric heating devices used a form of insulation that decreased in resistance as the device heated. I've forgotten the name of this heating system. In the USA, the name CALROD comes to mind. Such heaters would indeed cause a GFCI/RCCD to trip as they heated. I would guess she had this type of heater in the appliances. Best regards, Rich ------------------------------------------------------------- Richard Nute Quality Department Hewlett-Packard Company Product Regulations Group San Diego Division (SDD) Tel : 619 655 3329 16399 West Bernardo Drive FAX : 619 655 4979 San Diego, California 92127 e-mail: [email protected] -------------------------------------------------------------
