Wrist strap / mat grounding

[Ken Kopp-3]

As others have said .... NEVER use the "U" hole in the
outlet for a wrist-strap or anti-static mat connection!

Mine goes to the station ground buss ... 2" wide CU
strap ... that's connected directly to a number (12)
of 8' ground rods that are all bonded together with #8
CU wire.  There is no connection between this ground
system and the power company's entrance ground.

There is often measurable potential between the white
neutral wire, the green "ground" wire and a ground rod.

In some parts of Canada there is just one wire used in
the power distribution, especially in rural areas.  The
earth is the other side of the distribution circuit.  This
was the case for rural phone lines in the US in the past.

73! Ken Kopp - K0PP
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[Don Wilhelm-4]

Ken Kopp wrote:
> Mine goes to the station ground buss ... 2" wide CU
> strap ... that's connected directly to a number (12)
> of 8' ground rods that are all bonded together with #8
> CU wire.  There is no connection between this ground
> system and the power company's entrance ground.
>  
A ground rod that is not connected to the electrical utility entry
ground in in direct violation of National Electrical Code requirements.  
For the safety of yourself and others in your household, please add the
missing wire.  If a fault condition happens in your house wiring that
causes current to be carried on the 'green wire ground' conductor, the
potential between your extra ground and anything connected to the 'green
wire ground' can become quite high and anyone in contact with both can
become a conductor.


73,
Don W3FPR
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[Tim Havens]

Yes well said Don,
Ken this is a very unsafe condition to have two ground points which are not
tied together.  The potential between the two can be deadly in the event of
a fault.I know first hand from previous experience that this is true :-(

Be safe!  And be sure you understand why this NEC code is SO important.

Tim (NW0W)

On Tue, Sep 1, 2009 at 6:37 AM, Don Wilhelm <[hidden email]> wrote:

> Ken Kopp wrote:
> > Mine goes to the station ground buss ... 2" wide CU
> > strap ... that's connected directly to a number (12)
> > of 8' ground rods that are all bonded together with #8
> > CU wire.  There is no connection between this ground
> > system and the power company's entrance ground.
> >
> A ground rod that is not connected to the electrical utility entry
> ground in in direct violation of National Electrical Code requirements.
> For the safety of yourself and others in your household, please add the
> missing wire.  If a fault condition happens in your house wiring that
> causes current to be carried on the 'green wire ground' conductor, the
> potential between your extra ground and anything connected to the 'green
> wire ground' can become quite high and anyone in contact with both can
> become a conductor.
>
>
> 73,
> Don W3FPR
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>

--
"The whole world is you. Yet you keep thinking there is something else." -
Xuefeng Yicun 822-902 A.D.

Tim R. Havens
1232 Pine Street
Leadwood, MO 63653
mobile: [phone]
home: 573.747.4879
ham radio callsign: NW0W
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[David Woolley (E.L)]

Ken Kopp wrote:

> Mine goes to the station ground buss ... 2" wide CU
> strap ... that's connected directly to a number (12)
> of 8' ground rods that are all bonded together with #8
> CU wire.  There is no connection between this ground
> system and the power company's entrance ground.

Do not do this in the UK.  It breaches the electrical codes and can
create a significant shock hazard on systems with protective multiple
earthing (PME) under fault conditions.  All "functional" grounds must be
bonded to mains ground unless you are in an otherwise earth free area.

--
David Woolley
"we do not overly restrict the subject matter on the list, and we
encourage postings on a wide range of amateur radio related topics"
List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm>
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[Ken Kopp-3]

Hi Dave, others

You probably missed my "correction" to my hastily-
written posting.  The elaborate RF counterpoise and
power ground system --is-- connected to the mains
ground.  They -are bonded together.

I'm retired from an electric utility, so I have myself
convinced that I know the subject.  I just didn't put
the right wording into the message. (;-))

73! Ken Kopp - K0PP
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[Paul ZL3IN-2]

When I was about 8 years old I discovered that there was a few volts AC
between the hot and cold taps in my parents house, so I rigged a
night-light in the kitchen using a bicycle dynamo bulb. It glowed away
for years, mostly dim, but sometimes very bright, until I learned enough
about AC power systems to realize how dangerous it was. The hot water
cylinder and piping were grounded to the utility ground, and the cold
water piping was grounded via the metal water pipe feeding the house,
but the hot and cold were isolated by a plastic header tank. We lived
right next door to a power company 11kV/230 transformer. By the grace of
God, nobody was ever electrocuted in the house!

73 Paul ZL3IN
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[Mel]

May I please put an end to this off topic subject???   While all have presented various points and some good ones, they beg the original point that should be made about wrist straps and use during construction of static sensitive devices.  The ONLY point of concern is that the assembly surface where the parts are located and the person making contact with any components are at the same static potential.  A resistive conductive surface bench and a wrist strap electrically connected to it will present to any component the same static potential and the chance of component damage is reduced to near zero.  Whether the bench is connected to earth ground is not as important as a good static compliant conductive path from the wrist strap the the bench where assembly work will be done.  AND yes, the testing of the wrist strap to the conductive surface needs to be done regularly to ensure proper operation.  Part of ISO protocol.


Mel, K6KBE

--- On Tue, 9/1/09, Paul ZL3IN <[hidden email]> wrote:

From: Paul ZL3IN <[hidden email]>
Subject: Re: [Elecraft] Wrist strap / mat grounding
To: [hidden email]
Date: Tuesday, September 1, 2009, 3:33 PM

When I was about 8 years old I discovered that there was a few volts AC
between the hot and cold taps in my parents house, so I rigged a
night-light in the kitchen using a bicycle dynamo bulb. It glowed away
for years, mostly dim, but sometimes very bright, until I learned enough
about AC power systems to realize how dangerous it was. The hot water
cylinder and piping were grounded to the utility ground, and the cold
water piping was grounded via the metal water pipe feeding the house,
but the hot and cold were isolated by a plastic header tank. We lived
right next door to a power company 11kV/230 transformer. By the grace of
God, nobody was ever electrocuted in the house!

73 Paul ZL3IN
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[Eric Swartz - WA6HHQ]

(Note added for this parallel topic.)

Guys - We're getting a flood of posts on this topic. Let's slow it down
a bit and end this thread totally by the end of today.
(0700 UTC)

73, Eric
Elecraft List Moderator



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