Posted by
BiBrun on
URL: https://www.es-forum.com/Dirty-Power-tp1545631p1545636.html
Aha--low voltage lights! It's the power supply.
Common mode means the noise is the same on hot and neutral.
Apparently this happens especially with switching power supplies, and
may depend on the load I think. Unfortunately I have no experience
measuring it.
The info comes from Bruce McCreary, aka the "ES engineer".
Theoretically you could measure common mode by the voltage of neutral to
ground. But in a house the ground is bonded to neutral, so it might work
kind
of for detecting sources in the house but it useless for looking at dirty
power
from outside, unless you use a grounding rod not connected to power company
stuff.
The other big question is whether the power distribution in your area is Wye
or Delta.
Wye is much more common except in California. With Delta you are
'transformer isolated'
giving cleaner power, but with Wye you are not. So dirty power flows freely
through the transformers via the
neutral.
I am pretty new to this stuff... I can try to put you in touch with Bruce if
you want.
He has built low EMF computers etc.
Bill
On Nov 30, 2007 9:03 PM, jaime_schunkewitz <
[hidden email]>
wrote:
> --- In
[hidden email] <eSens%40yahoogroups.com>, "Bill Bruno"
> <wbruno@...> wrote:
> >
> > Were you measuring hot to neutral or hot to a true ground?
>
> I'm measuring and filtering Hot to Neutral.
>
> >
> > Common mode noise by definition will not show up on hot relative to
> neutral.
>
> Can you please describe common mode noise in more detail, Bill?
> How do you measure it? It's common between what lines? How do you
> filter it? Why will it not show up on hot relative to neutral?
>
> >
> > Do you find halogen bulbs different from incandescent? If so, why
> is that?
> > I assume there is no dimmer switch involved? I suspect track
> lights in
> > general
> > might actually be prone to interference (i.e., act like an antenna)
> if they
> > are
> > true track lights in the sense that you can slide the lamps in the
> track
> > (after loosening a screw).
>
> They're 12 volt bulbs. It looks like there's a switching supply
> module feeding each bulb. Incadescents don't produce such noise.
>
> >
> > Thanks for posting-
> > Bill
>
>
>
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