The Sunday 2005-03-20 at 13:10 -0600, Danny Sauer wrote:
Those are called GFCI (ground fault circuit interrupter) outlets in the USA, and are typically only installed near water (in the kitchen and bathroom), as they cost about $7 instead of $0.50 for regular outlets. Many (most?) new houses are built as cheaply as possible over here. :(
They are mandatory in Spain for "new" installations, since perhaps about 20 years ago. The whole house is protected by a "main current limiter" and a "differential switch" in cascade. After that come section limiters, four or six usually (15 to 30A). The differential switch (equivalent to your GFCI) thus protects the whole installation. If one of the two wires carries 20mA more or less than the other (meaning that some is leaking to earth, perhaps through somebody's leg) it switches off everything fast. Of course, our 220V is more dangerous than your 110 (for electrocution, perhaps less for fire), that's why they are mandatory, I guess. So, those things in the movies with the bad guy "dropping" a hair dryer in the bathtub should be useless ;-) On the other hand... do you know that computer's power supplies usually leak a bit to ground? I suppose it is the filter section of switched mode power sources. Sometimes a lab full of PCs can be a nightmare for the GFCI. -- Cheers, Carlos Robinson