>the ground wire must now be on top of the stack-up.
Never, from what I've ever heard. Ground connection should be the first one on,
last one to come off.
Eric Petitpierre
Pulsecom
Herndon, VA
[email protected]
______________________________ Reply Separator _________________________________
Subject: RE: Proper Protective Earth Ground Symbol
Author: [email protected] at smtp
List-Post: [email protected]
Date: 1/18/00 11:00 AM
I agree with Kurt's summary of the ground marking and stack-up requirements,
but there is a point of clarification I would like to have. Years past, it
was explained to me that an appliance inlet ground must be first on the
stack-up against the chassis. The point was to ensure that any maintenance
action did not compromise the grounding of the enclosure. In the case of a
power cord, the opposite was true however. Since a power cord is by
definition frequently replaceable (hence the specific requirements for
strain relief's and terminal blocks) the ground wire must now be on top of
the stack-up. This facilitates easy replacement without jeopardizing the
ground.
What is the consensus on this?
Rick Busche
Evans & Sutherland
[email protected]
-----Original Message-----
From: Andrews, Kurt [mailto:[email protected]]
Sent: Tuesday, January 18, 2000 8:26 AM
To: [email protected]; Jackson; William;
'[email protected]'
Subject: RE: Proper Protective Earth Ground Symbol
Jim,
For the Protective Earth Terminal, that is the ground from
the power cord or
IEC Inlet that should be located just inside the equipment
needs to be IEC
417, No. 5019, the circle upside down tree. Also the
incoming ground MUST be
the first on a stud and secured by its own lockwasher and
nut. You may then
stack other grounds to other parts of the equipment on top
of this ground.
You may use a separate lockwasher and nut for each
additional ground or one
for all of the additional grounds. There may also be other
ground studs in
the unit if you don't want to run wires to the Protective
Earth Terminal.
This assumes an all metal construction, which is what we
use. We have used
both the upside down tree symbol, IEC 417 No. 5017, and the
Equipotentiality
symbol, IEC 417 No. 5021 for these additional grounds with
no problems. For
an additional ground on the outside of the equipment we have
used the same
symbol as for the Protective Earth Terminal. When we sent a
unit in once for
safety testing to UL we had the upside down tree without the
circle next to
an outside ground terminal and they told us it has to be the
one with the
circle around it. I would think that the frame ground
symbol, IEC 417 No.
5020 (pitchfork) would also be acceptable although we
haven't used it.
Hope this helps,
Kurt Andrews
Compliance Engineer
Tracewell Systems, Inc.
567 Enterprise Dr.
Westerville, OH 43081
Ph. 614-846-6175
Fax 614-846-7791
Email: [email protected]
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