On Monday 26 March 2018 00:29:24 Chris Albertson wrote: > 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.
Here, when I replaced my service with a 200amp, making the house a 60 amp subcircuit, in 2007, getting ready to build on a garage, I had to drill thru the concrete, and place 2, 8' ground rods, 8 feet apart, in the holes both tied to the neutral and to the static. Up till then I lost a modem or something everytime the can pole across the street got hit. I have not lost a thing since. The 50kw can itself has been blown, but I've not been hurt. I'd call that a plus. > > 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 -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. 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