Re: Equipotential bonding

On Fri, 02 Jan 2009 11:28:00 +0000, Ian Jackson wrote:

In article <EtWdnYpt9rRyfMDUnZ2dnUVZ8sTinZ2d@xxxxxx>, beamends
<sales@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Tue, 30 Dec 2008 12:56:41 +0000, Lester Caine wrote:
So having a clean 0V reference makes perfect sense to me, with a
nice quiet +24V supply in my case to take load off the DCC feeds.

0V is a tested connection to physical earth, it has a specific meaning
when wiring panels, transformers etc.

Maybe that's what 0V means in the US when talking about mains wiring.
But in this (UK) group and in the context of model trains, it doesn't
mean anything of the kind.

0V in this context just means the nominal baseline against which other
voltages (in the low voltage system) are quoted. It may or may not be
earthed inside the mains power supply, but there is no need to earth it
separately.

Indeed in some systems with multiple power supply rails, a rail other
than the nominal 0V may be earthed inside the PSU although I would
expect most model railway systems to avoid that - since in such a setup
a naive user who earths the 0V output PSU terminal effectively shorts
out the PSU.

(Assuming of course you're using reputable equipment!)

I can assure you that 0V specifically means a true reference earth in
panel and control wiring - indeed for testing of electrical switch gear
the factory will have a line to each test station very visibly marked as
such, and testing is not valid unless it is connected.

However, 0V has also crept in automotive applications as meaning the same
as battey -ve, but that is not strictly correct, though I suppose common
usage overrules all, hence the confusion.

Cheers
Richard


--
I have become...............comfortably numb
.

Relevant Pages

  • Re: Equipotential bonding
    ... 0V is a tested connection to physical earth, it has a specific meaning ... when wiring panels, transformers etc. ...
    (uk.rec.models.rail)
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  • Re: Equipotential bonding
    ... 0V is a tested connection to physical earth, ... voltages (in the low voltage system) are quoted. ... Indeed in some systems with multiple power supply rails, ... setup a naive user who earths the 0V output PSU terminal effectively ...
    (uk.rec.models.rail)
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