Curt McNamara <[email protected]> wrote on 12/12/2007 08:07:16 AM: > I admit to not having followed all this -- however I know an engineer > who works on building issues for people. Supposedly the most significant > problem is the neutral bonding to ground inside the house. If this is > done in such a way that significant neutral current flows through the > pipes instead of the wiring then there is significantly more 60Hz > magnetic field. > > The folks most concerned are those with autistic kids, who seem to be > more sensitive to this. > > The typical fix is to isolate (electrically) the pipes inside the house > from the main (with a piece of plastic pipe). > > If you want any more details please send questions to me and I will > forward to him. > > As to personal experience, as a teenager I used to work on TV antennas > and found the voltage present at the terminal of a receive antenna on a > roof was surprisingly strong. Typically I couldn't keep my fingers on it > and needed insulation. It is possible this was related to weather > conditions. > > Curt
If you felt AC voltage on the TV antenna (felt a 120 Hz buzz), then most likely it was due to the TV receiver. Up to a certain time, it was common to put a Y-cap to chassis ground from both the neutral and hot conductors, with no safety ground (two wire, non-polarized plug). This forms a capacitive voltage divider, so the chassis is floating at about 60 volts AC. The antenna input terminals of the TV were often tied (at 60 Hz) to chassis ground via a capacitor and/or resistor. Thus there was some 60 Hz leakage current out the antenna terminals. The rest of the TV was usually well insulated, so no leakage current was noticeable in normal use. Don Borowski Schweitzer Engineering Labs Pullman, WA, USA - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
