On Wednesday, September 07, 2011 08:35:06 AM Steve Blackmore did opine: > On Tue, 6 Sep 2011 23:30:11 +0100, you wrote: > >On 6 September 2011 23:14, Steve Blackmore <[email protected]> wrote: > >> I've regularly seen much higher than a few volts. I think it depends > >> a lot on location and local wiring condition/type and ground > >> conditions. > > > >I am not sure I want to think to hard about this, because then I will > >end up getting bogged down in whether my installation is TN-S, > >TN-C-S, TT or TN-T and whether I should do away with the exported > >earth on the SWA, put in a spike and go TT locally. > > They seem to have stopped installing ground spikes these days. Cross > bonding to water or gas pipes is no longer a good earth path (plastic > pipes) and the underground cables are no longer lead coated so your > earth now relies on how good the earth is inside your mains supply. The > further from the substation you are, the worse it seems to get :( > > Put a ground spike in additionally as a belt and braces measure if you > can. > > Steve Blackmore > --
When I replaced the 60A service to my house with a 200A box about 15 years back, one of the things the NEC codebook now required was a pair of ground rods, at least as far apart as their length (8 feet), with 8 ga (or better) bonding to the neutral AND static grounds, the only place in the system on my side of the meter where it is legal to bond neutral and static grounds together. I had a heck of a time getting through some old concrete to do that, around 8" of it, but have not lost a single item of electronics due to nearby EMP hits since. Before then, despite having a single point supply setup in this room, I was losing a modem at least annually from nearby nits. Cheers, gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://204.111.67.138:85/gene> Some performers on television appear to be horrible people, but when you finally get to know them in person, they turn out to be even worse. -- Avery ------------------------------------------------------------------------------ Using storage to extend the benefits of virtualization and iSCSI Virtualization increases hardware utilization and delivers a new level of agility. Learn what those decisions are and how to modernize your storage and backup environments for virtualization. http://www.accelacomm.com/jaw/sfnl/114/51434361/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
