[TowerTalk] Grounding Multiple Buildings

[John Lloyd]

Jim,

Many of today's switching power supplies with RFI filters in the AC input have these capacitor from the line input to ground.

John Lloyd, K7JL




Message: 6
Date: Mon, 15 Sep 2014 07:36:53 -0700
From: Jim Lux<jimlux at earthlink.net>
To:towertalk at contesting.com
Subject: Re: [TowerTalk] Grounding Multiple Buildings
Message-ID:<5416F985.6010304 at earthlink.net>
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On 9/15/14, 7:09 AM, David Jordan wrote:

> Here is how the NAVY would perform the grounding:
> http://www.hnsa.org/doc/radio/index.htm
>
> -

How the navy would do it *in 1946*.
And, there's actually nothing in there about grounding, or electrical
wiring practices. The antennas they talk about are dipoles, for the most
part.

In general, old documents aren't always a good source of "good
construction and engineering practice". There has been substantial
change in grounding, bonding, transient suppression knowledge and
practice in the last 70 years, particularly when it comes to safety.

This is not to say that information in old publications is actually
wrong, but that it might be incomplete or inappropriate in view of
today's practices.  A nice example is old versions of the ARRL handbook
which recommend connecting 0.1 uF capacitors between power line and
chassis for filtering. Today, this would be considered very bad
practice: capacitor failure would lead to a potential line/chassis
short, leakage currents (0.1 uf = 5 mA @ 120V) that will trip a GFCI, etc.