[Gllug] OT: Merging UPS outputs

[Chris Bell]

On Mon 22 Aug, Russell Howe wrote:
> 

> 
> Hm.. this would be a single earth point per circuit, right? (with a
> transformer joining circuits together, so there was no direct current
> path between them). Otherwise, it would sound like a bad idea.. I was of
> the impression that multiple earthing points on a circuit was something
> you strived to avoid, due to ground loops etc.
> 
> Then again, I'm certainly no electrician and won't even pretend I know
> what I'm talking about, so please point any misguided musings.
> 
   It is no longer standard practice to provide an earth cable connection to
the customer, while the "neutral" is now "earthed" to ground at the incoming
main supply. The neutral connection is therefore connected to multiple local
earths, at least one per customer locally. All modern installations have an
earth spike and earth bonds to all other services.
   All metal items that can be touched should be earthed, and that includes
the metal handle on a plastic door or window, and metal fittings in a
ceramic sink or the loo connected only via plastic pipes. Many metal water
pipes are being replaced by plastic, and a substitute earth cable must be
provided to bridge on to any remaining metal items.
   My home incoming supply is an armoured cable, and the armouring may
constitute an earth, but should not be taken as reliable because the
armouring may be rusty and is covered with tarred cloth.

-- 
Chris Bell

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