On Fri, Mar 23, 2018 at 4:24 PM, a k <pccncmach...@gmail.com> wrote: > I am in portland . > 30 to 40 v ac I read between water pipe _ which is real ground and ground > on the outlet pin that has cylindrical shape. > Is this normal?
No. Something is seriously wrong to the point off being dangerously wrong. At some point where the power comes into your building the grounded wire and the cold water pipe should be connected together. Also at the same location where should be a ground rod or a connection to metal that was embedded in a concrete foundation for this purpose. 30 volts means something is broken. In the US we have a neutral conductor. It is the longer of the two slot-shape holes in the outlet. This pin is allowed to be a few volts above ground but only a few. You don't say but you might be in an outbuilding like a detached garage. Some times these are written up by a "do it yourself" type home owner who does not wrong. There are a million ways it might be broken, lose conations, incompetent installation, water filling a a buried conduit (yes I've seen this, completely flooded) Or the most likely two cases: 1) You house was built before a ground outlet was required and there are no ground wires. That three-prong outlet was install later and the ground pin is not even hooked up. 2) Some one used metal conduit for the ground. This used to be allowed. Then some section of the conduit became rusted and you are back to #1 above. You might take the outlet off and look to see if there is even a green or bare wire. But with 30 volts to the cold water line, it is take for a electrician to look. I would walk this problem backwards to the course. Or all the outlets like this? > > > > > On Mar 23, 2018 4:03 PM, "Chris Albertson" <albertson.ch...@gmail.com> > wrote: > >> Aram, >> >> Where to you live? In North America, UK, ....? >> >> Building wiring conventions are different in different places. but in >> general your system, taken as a whole needs to be connected to exactly ONE >> ground reference. No more no less. The best way to place a bolt some >> place and define that is "The Ground" >> >> If you have 30+ volts AC on a ground pin on an outlet you have a problem >> that needs to be looked at by a good electrician. It should never be that >> high. Some cases are thinks like corosion and loose connections. One >> cause I that think of is that in some older buildings they were allowed to >> use metal conduit as the ground connection. Works OK at first but meta >> conduit rusts ofter time. Now day we are required to pull a group cable >> >> On Fri, Mar 23, 2018 at 2:04 PM, a k <pccncmach...@gmail.com> wrote: >> >> > hi >> > i reassemble my lcnc mill, and i found that axis move by them self. >> > i think it is something to do with static electricity. >> > i found ground - and when grounded lcnc body of machine - breaker turn >> off. >> > i measure with dc voltage between machine and ground 2. vdc and when i >> > measure ac voltage between lcnc machine and ground it was 35 v AC. >> > >> > i know that when use real ground like a water pipe and ground in outlet >> > there always will be current they always be 30 v ac. >> > can it cause problem? >> > >> > thanks >> > aram >> > ------------------------------------------------------------ >> > ------------------ >> > Check out the vibrant tech community on one of the world's most >> > engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> > _______________________________________________ >> > Emc-users mailing list >> > Emc-users@lists.sourceforge.net >> > https://lists.sourceforge.net/lists/listinfo/emc-users >> > >> >> >> >> -- >> >> Chris Albertson >> Redondo Beach, California >> ------------------------------------------------------------ >> ------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
