Patrick,
That certainly is bad news about the open ground on an AC outlet. However,
the "tingle" you get with 2-prong, non-polarized plug devices in metal
housings has nothing to do with the AC wiring; rather, that is leakage
current on the chassis or case of an item, and is due to either one or more
AC line by-pass caps or the inherent capacitance between the mounting frame
of a transformer or motor and the primary winding. If you get the tingle
when the device is "off", then reversing the plug should help. That's
because the power switch on the device works on only one side of the power
cord. The problem can be reduced by cutting off the factory power plug and
replacing it with a polarized plug that you can buy at the hardware store.
73,
Dale Svetanoff, WA9ENA
Sr EMC Engineer
E-N-A Systems, LLC
Specializing in shielding applications, system grounding, and lightning
protection
> [Original Message]
> From: Patrick Dyer <pjdyer@swbell.net>
> To: <jim@audiosystemsgroup.com>; rfi@contesting.com <rfi@contesting.com>
> Date: 9/12/2012 3:57:22
> Subject: Re: [RFI] Noise changes when room lights turn on / off
>
> For a long time I had a similar puzzling noise on 20m that shifted in
> frequency when the central air conditioning unit came on/off. As I'm on
> that band only for contests with a low fan-dipole antenna it wasn't a
> high-priority item to track down.
>
> Then one day with a 30-50 MHz receiver on I happened to walk thru the
> dinette and heard it. It was quickly isolated to the charging unit for
> a pair of (c. 2002) Cobra FRS handhelds there.
>
> Sometime before this that circuit had triggered a warning on an APC UPS
> unit when plugged in there. A Klein RT100 tester says "open ground".
> From the get-go here in Jun 1972 it had been noticed that some
> non-polarized plug metal appliances would present a tingling to the
> touch if plugged in one way. If this had been determined to be a
> contractor-wiring error at the start a demand for remedy would have been
> instituted.
>
> 73, Pat - WA5IYX
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