On Thu, Dec 2, 2010 at 22:39, Seth Mattinen <sethm@rollernet.us> wrote: ...
Arc fault breakers are a very new code requirement which I believe is primarily targeted at sleeping areas. My place has them (built about 4 years ago) on the bedroom outlet circuits. If I spin the socket switch on one of the table lamps too fast it'll trip.
The NFPA priority is to protect life (property/equipment are there too, but lower in priority). (Note that while NFPA 70 is not required, most jurisdictions eventually turn it into their law/codes. But exceptions exist, and your specific requirements may vary, and not all jurisdictions adopt the new rules immediately. Some still (only) require NFPA 70-2005, and not NFPA 70-2008. There is no known case where applying more recent practices has resulted in liability, so some contractors may build to 2008 when only 2005 is being enforced by the inspector). Now that most outlets are grounded, and GFCIs are in locations where people are likely to be the source to ground ("wet" areas), one of the bigger remaining issues for loss of life in the home due to electricity was in the bedroom with arcing between the hot/neutral when people were asleep (and could be overwhelmed by the smoke before they could get out of the house). Another addition to the code a few years ago was what I call "child proofing" the outlets(*). You will see all new (but not existing old stock) outlets having a (usually) mechanical cover for the slots which requires a plug to be pushed in (only the pressure from both prongs will open the cover) to protect against the inquisitive fork or finger problem. NFPA 70 does take into account industry recommendations (for the conspiracy theorists), and the perceived return on the costs (something that saves 1 life over 10 years but costs billions is not likely to make it into "code"). Gary (*) Technically, I think these are called Tamper-Resistant Receptacles, and are required in all new work as of NFPA 70-2008.