Chris PSNet,
This issue was discussed on this forum last January. Check the archives
for more details...
There is a considerable body of knowledge that shows for the usual
socket outlets (NEMA 15 in North America) or less technical, but equally
acceptable information for similar Euro
by: cc:
emc-p...@majordomo.ieee.org
owner-emc-pstc@majordomSubject: Re: Secondary
Grounding
o.ieee.org
Hi Chris:
Consider a product with two, independent protective
grounding/earthing connections. This may be by
means of two power cords (as is done for uptime
reliablity by employing parallel power supplies) or
by means of one power cord and a separate ground
connection (as, for example, by
Hmm,
This question centers around whether two separate ground cables equals
double protection.
Safety standards call for single fault testing. For Class I equipment, one
of the single fault test conditions is removal of the ground connection.
I'm curious how most test labs would
wiring or other external factor. Using Class II insulation
would
require a third fault, i.e. a failure of the supplemental insulation, for a
shock hazard
to occur.
Applying the principles above, there would be no need to provide parallel or
secondary grounding paths.
George Alspaugh
Lexmark
Martin,
I agree with Peter about designing even Class I (grounded) power supplies with
Class II (double-insulated) internal construction. Our Product Safety folks
require this, and have required it going back to our IBM Lexington days. The
grounding of wall outlets can not be trusted in many
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-Original Message-
From: marti...@appliedbiosystems.com [mailto:marti...@appliedbiosystems.com]
Sent: Thursday, May 31, 2001 12:25 AM
To: emc-p...@majordomo.ieee.org
Subject: Secondary Grounding
Group,
This is a general
of08958f39.0dda511c-on88256a5c.007a1...@pe-c.com,
marti...@appliedbiosystems.com inimitably wrote:
In order to avoid test failures during a single fault condition where the
primary ground is removed, what design methods can be used to add a second
ground to the system so that a ground is still
Group,
This is a general product safety question:
In order to avoid test failures during a single fault condition where the
primary ground is removed, what design methods can be used to add a second
ground to the system so that a ground is still provided even during a
single fault condition of
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