I appreciate the responses to this but I want to emphasize that the
"standards" give you an out to open earth leakage current
testing if the mains connection means meets certain requirements. This
has nothing to do with internal product construction of the protective
bonding circuit. That is covered elsewhere in most standards. Therefore,
what is the origin of this requirement and why are you allowed to waive a
touch current test if your mains connection means meets certain plug type
requirements?
Also, I am aware of the two-wire USA NEMA 1-15P versus the three wire
NEMA 5-15P plug/socket connection issues. Is it because of this that we
have the plug type exemptions from touch current testing?
Best regards,
Ron Wellman
> As I recall, touch current is effectively measured with the ground
pin
> lifted. The rationale is that there should be no hazard even if
the
> safety ground is left floating.
>
>
>
> Joe Randolph
>
> Telecom Design Consultant
>
> Randolph Telecom, Inc.
>
> 781-721-2848 (USA)
>
> <mailto:[email protected]> [email protected]
>
> <http://www.randolph-telecom.com>
http://www.randolph-telecom.com
>
>
>
>
From: Scott Aldous [mailto:[email protected]]
> Sent: Monday, November 10, 2014 11:40 AM
> To: [email protected]
> Subject: Re: [PSES] Open Protective Earth Conductor Fault
>
>
>
> Standards typically apply touch or leakage current limits to
> plug-connected products. I believe that potential for an unreliable
ground
> connection at the receptacle the product plugs into is at least
as
> important a concern as the potential for faults inside the product
itself.
> For example, in an old house in the USA with 2 prong outlets, it is
common
> for the homeowner to simply use "cheater plug" adapters to
avoid having to
> connect the ground pin at all. This could well be considered outside
the
> intended use, but people will do it anyway, at least for a
consumer
> product.
>
>
>
> On Sun, Nov 9, 2014 at 11:00 PM, John Woodgate
<[email protected]
> <mailto:[email protected]> > wrote:
>
> In message <[email protected]
> <http://wellman.com> >, dated Sun, 9 Nov 2014, Ronald
Wellman
> <[email protected] <mailto:[email protected]> >
writes:
>
>
> I would like to know if anyone has had an experience where a
product
> actually experienced an open protective earth conductor fault after
it
> left the factory. If you have, what was the Root Cause?
>
>
> Two cases:
>
> - failure of weld of PE connection stud to metalwork;
>
> - enclosure fixing screw severed PE connection in mains cable
internal to
> the product.
>
> Both products were small and no excessive touch current occurred.
>
> I ask this because there are various standards that allow you to
waive the
> touch current test because of the product connection means to the
> building branch circuit. Because of this, I would like to know who
has
> actually experienced a touch current hazard and under what
conditions.
>
>
> Regardless of what the standard allows, I would measure and minimise
touch
> current, and as far as possible make the internal PE connection
secure
> (i.e. screw or nut and bolt, no welded stud).
> --
> OOO - Own Opinions Only. With best wishes. See
www.jmwa.demon.co.uk
> <http://www.jmwa.demon.co.uk>
> Quid faciamus nisi sit?
> John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
>
> -
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> --
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> Scott Aldous
>
> Compliance Engineer
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