Re: [PSES] High Touch Current and GFCIs

[Richard Nute]

 

 

Hi Brian:

 

“Touch current” is current through the body when it touches two conductors.  By 
convention, touch current is measured through a 2,000-ohm resistor in series 
with the PE conductor.  Touch current only exists if two conductors are 
touched, for example, when the PE is open.  If the current is sufficient, it 
can cause enough L-N imbalance current to trip the GFCI.

 

PE current is measured with an ammeter in series with the PE conductor.  In 
your situation, PE current, not touch current, trips the GFCI (because the PE 
is not open).  

 

An isolation transformer on the load side of a GFCI will provide a return 
current path to the isolation transformer rather than an imbalance of current 
through the GFCI.  (I am assuming the isolation transformer neutral is 
connected to ground).  The GFCI will not see an imbalance between L and N. 

 

Best regards,

Rich

 

From: Brian Kunde  
Sent: Monday, August 29, 2022 5:45 AM
To: ri...@ieee.org
Cc: EMC-PSTC@listserv.ieee.org
Subject: Re: [PSES] High Touch Current and GFCIs

 

If I have EE or a rake of equipment or several pieces of equipment plugged into 
a power strip that has a combined touch current that trips a GFCI, what can be 
done about that?  Will an isolation transformer solve the problem?

 

Thanks,

The Other Brian

 


-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
_
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

Re: [PSES] High Touch Current and GFCIs

[John E Allen]

Afternoon

 

W.r.t. Doug’s comments, & FWIW, here are a few of my experiences & suggestions:

 

1.  Many years ago I had a customer complain that a model of monitor that 
HP supplied to the UK exceeded the 0.75mA limit. After a lot of investigation 
(including building a small measuring set with switchable IEC and other bypass 
networks) and discussion, I concluded that the monitor was OK but the customer 
must have been using a measuring set with no IEC HF “body simulation” network – 
and that resulted in his measurements being higher than the IEC limit and 
that’s why he had complained. I explained that out to him and no more 
complaints were then heard!

 

Nevertheless, do be aware of that “problem” because I later found that many of 
the cheap  combined “hipot/ leakage/touch current” test-sets on the market ( at 
least in the UK/Europe) still don’t (or at least didn’t a very few years ago) 
include an IEC-type network to filter out the HF currents – therefore they are 
VERY prone to giving very high & fluctuating readings that can provoke 
customers to complain, as per my experience above!!! (I had to use several of 
those on occasions and simply had to ignore the touch/leakage current readings 
because I knew why it was happing!)

 

2.  As has been said here, racked systems pose specific issues because of 
the multiple leakage paths which the assembler can only partially control in 
many cases due to the difficulties in removing filters on individual units, 
and, even then, how does one ensure that subsequent field-placement units are 
similarly modded before installation? (generally you can’t, unless you create 
specific part numbers for the modded units and accompanied by very specific 
replacement instructions!) 

 

3.  Isolation transformers for fully loaded racks will be both heavy and 
expensive – if you can even find space for them? Not really realistic in most 
environments, except possibly medical, unless there is an overriding reason to 
limit possible leakage currents into other associated equipment?

 

4.  Personally, with IT & Industrial electronics systems, I found it 
easier, quicker and cheaper to take advantage of the relaxed 5mA leakage limit 
afforded by specifying that an additional heavy duty grounding cable be 
installed from the rack to the building distribution system – it’s relatively 
easy to require in the installation instructions and then relatively easy to 
actually install in most well-controlled & managed industrial (and even 
office)-type buildings.

 

That gets you out of the problem of having to minutely control the overall rack 
configuration - in my experience both suppliers and end-users are prone to 
changing rack assemblies for something “better” or “new” without telling the 
engineering compliance guys. That extra cable should give a reasonable “safety 
margin” for someone to add (unbeknown to you!) additional units to the rack to 
“upgrade” / “enhance” its facilities.

 

OTOH, just make sure you stick a (preferably several!) large “High Leakage” 
/”Touch current” label on the rack near the power inlet (and possibly on the 
control /connector panels) to alert users to the situation, and explain the 
requirements in the installation & operation instructions.

 

5.  As has been noted, the possible effects on GFCI’s/RCDs  etc., will vary 
somewhat unpredictably around the World according to the distribution systems 
and the actual GFC/RCDs in use. Therefore there may well be no “fits all 
solution” and one might have to negotiate with individual local inspectors 
(etc) on what will be acceptable (&/or even actually test those on sale locally 
to try to identify ones less sensitive to nuisance tripping??) 

 

FWIW, in one “extreme” case I had to resort to a separate RCD to cover a 
particularly leaky rack subsystem which couldn’t be otherwise “fixed” as  it 
had to have multiple “military-grade mains filters” with very low frequency 
bandpass characteristics, and thus high value X/Y capacitors and leakage! 

 

My “3 pennyworth ” / “5 cents” contributions, and anyone is welcome to take 
issue – but please do consider possible “real life” situations before you fire 
the big guns!

 

John E Allen

W. London, UK

 

From: Douglas E Powell  
Sent: 24 August 2022 23:22
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] High Touch Current and GFCIs

 

Brian,

 

Depending on the class of that circuit breaker, the answer is probably yes.  
See this article 
<https://code-authorities.ul.com/about/blog/understanding-ground-fault-and-leakage-current-protection/#:~:text=It%20states%20that%20a%20Class,Ground%2D%20Fault%20Circuit%2DInterrupters.>
 

 

Sometimes when dealing with high leakage current the relevant safety standard 
allows you to go to a much higher level if you provide secondary chassis 
grounding (earthing) and a warning label. Of course, this all depends on how 
the product is configured. Chec

Re: [PSES] High Touch Current and GFCIs

[Don Gies]

If your equipment exceeds touch current limits by summation, and if you think 
your equipment is going to be located in areas where the National Electrical 
Code or Canadian Electrical Code, Part I mandate the installation of 
GFCI-protected branch circuits, then you would certainly need to accommodate 
for this in your design and installation instructions.

I don’t believe using an isolated transformer to create an internal 
separately-derived power system would work because you would still be 
connecting all of your pluggable equipment (Type A) to ground.

If the equipment is industrial, then the best solution would be to use an 
industrial plug (Pluggable Equipment Type B) or permanent connection and comply 
with the rules that permit equipment to exceed touch current limits.  This is 
typical of many IEC standards, including IEC 62368-1.  For equipment such as 
AC-powered outdoor mobile telephone network equipment, this  tends to be more 
of the norm than the exception, as you tend to get quite a bit of touch current 
when the system is ungrounded for test, but never close to the  5% of the input 
current allowed for protective conductor current.

Best regards,

Don Gies




Internal
From: Brian Kunde 
Sent: Monday, August 29, 2022 8:45 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] High Touch Current and GFCIs


[External email: Use caution with links and attachments]




If I have EE or a rake of equipment or several pieces of equipment plugged into 
a power strip that has a combined touch current that trips a GFCI, what can be 
done about that?  Will an isolation transformer solve the problem?

Thanks,
The Other Brian

On Sat, Aug 27, 2022 at 6:38 PM Richard Nute 
mailto:ri...@ieee.org>> wrote:

I wouldn’t describe the phenomenon as “cancellation.”  The touch current is 
always present and must have a path to earth/ground.

The equivalent equipment circuit:
Y1 capacitor L-(line)-to-PE.
Y2 capacitor N-(neutral)-to-PE.  Capacitor value is 25x Y1 capacitor value.
4.6 volts N-to-(grounded)-PE.

In the USA, N is connected to a ground rod at the building service entrance.  
PE is connected to N at the breaker box.  In the building, PE is parallel to N, 
but is a non-current-carrying conductor except in the case of a fault.

The Y1 and Y2 capacitors are in series and comprise a voltage divider to an 
open PE.  Because the Y2 capacitor is 25x the Y1 capacitor, the open-circuit 
voltage at the PE connection is very low compared the line voltage (instead of 
the usual half the line voltage).

Normal condition touch current path is from L to Y1 to PE (open) to a 2,000-ohm 
resistor to ground,  Touch current is calculated using Ohm’s Law from the 
measured voltage across the 2,000-ohm resistor. The 2,000-ohm resistor is (in 
essence) parallel to the Y2 capacitor.  Some of the L-to-Y1 current (not touch 
current!) returns to ground through the Y2-N-ground circuit, depending on the 
parallel network of capacitance reactance and the 2,000-ohm resistor.

Reverse polarity (L and N reversed in the supply to the equipment) current path 
is N to Y2 to PE (open) to the 2,000-ohm resistor to ground.  Because Y2 is 25x 
Y1, the touch current is much higher than normal polarity.  As in the normal 
polarity condition, some of the current (very small) returns to ground through 
the Y1 capacitor.

If the Y1 and Y2 capacitors are of equal value, the supply voltage is 120 
volts, and the touch current limit is 0.5 mA, the Y1 and Y2 capacitance 
reactance is 238,000 ohms each. The Y2 capacitance is shunted by the 2,000-ohm 
resistor and can be ignored as the voltage across the Y2 and 2,000-ohm resistor 
is 1 volt.  (The current through the 238,000-ohm reactance is 4.2 microamps.)

We have a parallel circuit to ground from the junction of Y1 and Y2 when the PE 
is open and when touch current is being measured.  One circuit to ground is 
through the touch current measuring circuit.  The other circuit to ground (via 
the N) is through the Y2 capacitor. If the Y2 reactance is small, a significant 
N current can be in that path to ground thereby reducing the touch current, not 
a partial cancel of the touch current.

Best regards,
Rich


From: John Woodgate mailto:j...@woodjohn.uk>>
Sent: Thursday, August 25, 2022 12:32 PM
To: ri...@ieee.org<mailto:ri...@ieee.org>; 
EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] High Touch Current and GFCIs


There is also a question in my mind as to whether there can be partial 
cancellation of touch current. I suspect this is highly improbable in the US, 
due to the distribution system ensuring that the neutral has a very low voltage 
difference from the PEC. But in Europe, it's not inconceivable that the neutral 
could be, say, 4.6 V relative to PEC and the neutral-to-PEC capacitance 25 
times that of L to PEC, so that half the L-to-PEC leakage current is cancelled 

[PSES] Fwd: [PSES] High Touch Current and GFCIs

[John Woodgate]

Forgot to Reply All

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK
It all depends





 Forwarded Message 
Subject:Re: [PSES] High Touch Current and GFCIs
Date:   Mon, 29 Aug 2022 14:07:46 +0100
From:   John Woodgate 
Organisation:   J M Woodgate and Associates
To: Brian Kunde 



In all such cases, the best approach is to draw the schematic. You can 
usually see the current paths quite clearly then.  I can't answer your 
question because I can't visualise the schematic of your set-up. It may 
be that you are measuring the total current in the PEC somehow. What is 
the current rating of the fuse?


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK
It all depends



On 2022-08-29 13:41, Brian Kunde wrote:
When I run the Touch Current test and the EUT is not isolated from PE 
when I press the Test Button that opens the PE conductor, the meter on 
the test will max out. Sometimes it will even blow the fuse.  What is 
happening at that point?  Am I reading the Touch Current from every 
piece of equipment in the building?


Thanks,
The Other Brian

On Sat, Aug 27, 2022 at 6:38 PM Richard Nute  wrote:

I wouldn’t describe the phenomenon as “cancellation.”  The touch
current is always present and must have a path to earth/ground.

The equivalent equipment circuit:

Y1 capacitor L-(line)-to-PE.

Y2 capacitor N-(neutral)-to-PE.  Capacitor value is 25x Y1
capacitor value.

4.6 volts N-to-(grounded)-PE.

In the USA, N is connected to a ground rod at the building service
entrance.  PE is connected to N at the breaker box.  In the
building, PE is parallel to N, but is a non-current-carrying
conductor except in the case of a fault.

The Y1 and Y2 capacitors are in series and comprise a voltage
divider to an open PE.  Because the Y2 capacitor is 25x the Y1
capacitor, the open-circuit voltage at the PE connection is very
low compared the line voltage (instead of the usual half the line
voltage).

Normal condition touch current path is from L to Y1 to PE (open)
to a 2,000-ohm resistor to ground,  Touch current is calculated
using Ohm’s Law from the measured voltage across the 2,000-ohm
resistor. The 2,000-ohm resistor is (in essence) parallel to the
Y2 capacitor.  Some of the L-to-Y1 current (not touch current!)
returns to ground through the Y2-N-ground circuit, depending on
the parallel network of capacitance reactance and the 2,000-ohm
resistor.

Reverse polarity (L and N reversed in the supply to the equipment)
current path is N to Y2 to PE (open) to the 2,000-ohm resistor to
ground.  Because Y2 is 25x Y1, the touch current is much higher
than normal polarity.  As in the normal polarity condition, some
of the current (very small) returns to ground through the Y1
capacitor.

If the Y1 and Y2 capacitors are of equal value, the supply voltage
is 120 volts, and the touch current limit is 0.5 mA, the Y1 and Y2
capacitance reactance is 238,000 ohms each. The Y2 capacitance is
shunted by the 2,000-ohm resistor and can be ignored as the
voltage across the Y2 and 2,000-ohm resistor is 1 volt.  (The
current through the 238,000-ohm reactance is 4.2 microamps.)

We have a parallel circuit to ground from the junction of Y1 and
Y2 when the PE is open and when touch current is being measured. 
One circuit to ground is through the touch current measuring
circuit.  The other circuit to ground (via the N) is through the
Y2 capacitor. If the Y2 reactance is small, a significant N
current can be in that path to ground thereby reducing the touch
current, not a partial cancel of the touch current.

Best regards,

Rich

*From:*John Woodgate 
*Sent:* Thursday, August 25, 2022 12:32 PM
*To:* ri...@ieee.org; EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] High Touch Current and GFCIs

There is also a question in my mind as to whether there can be
partial cancellation of touch current. I suspect this is highly
improbable in the US, due to the distribution system ensuring that
the neutral has a very low voltage difference from the PEC. But in
Europe, it's not inconceivable that the neutral could be, say, 4.6
V relative to PEC and the neutral-to-PEC capacitance 25 times that
of L to PEC, so that half the L-to-PEC leakage current is
cancelled by the N to PEC current.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk <http://www.woodjohn.uk>
Rayleigh, Essex UK
It all depends


On 2022-08-25 19:12, Richard Nute wrote:

Re: [PSES] High Touch Current and GFCIs

[Brian Kunde]

If I have EE or a rake of equipment or several pieces of equipment plugged
into a power strip that has a combined touch current that trips a GFCI,
what can be done about that?  Will an isolation transformer solve the
problem?

Thanks,
The Other Brian

On Sat, Aug 27, 2022 at 6:38 PM Richard Nute  wrote:

>
>
> I wouldn’t describe the phenomenon as “cancellation.”  The touch current
> is always present and must have a path to earth/ground.
>
>
>
> The equivalent equipment circuit:
>
> Y1 capacitor L-(line)-to-PE.
>
> Y2 capacitor N-(neutral)-to-PE.  Capacitor value is 25x Y1 capacitor value.
>
> 4.6 volts N-to-(grounded)-PE.
>
>
>
> In the USA, N is connected to a ground rod at the building service
> entrance.  PE is connected to N at the breaker box.  In the building, PE is
> parallel to N, but is a non-current-carrying conductor except in the case
> of a fault.
>
>
>
> The Y1 and Y2 capacitors are in series and comprise a voltage divider to
> an open PE.  Because the Y2 capacitor is 25x the Y1 capacitor, the
> open-circuit voltage at the PE connection is very low compared the line
> voltage (instead of the usual half the line voltage).
>
>
>
> Normal condition touch current path is from L to Y1 to PE (open) to a
> 2,000-ohm resistor to ground,  Touch current is calculated using Ohm’s Law
> from the measured voltage across the 2,000-ohm resistor. The 2,000-ohm
> resistor is (in essence) parallel to the Y2 capacitor.  Some of the L-to-Y1
> current (not touch current!) returns to ground through the Y2-N-ground
> circuit, depending on the parallel network of capacitance reactance and the
> 2,000-ohm resistor.
>
>
>
> Reverse polarity (L and N reversed in the supply to the equipment) current
> path is N to Y2 to PE (open) to the 2,000-ohm resistor to ground.  Because
> Y2 is 25x Y1, the touch current is much higher than normal polarity.  As in
> the normal polarity condition, some of the current (very small) returns to
> ground through the Y1 capacitor.
>
>
>
> If the Y1 and Y2 capacitors are of equal value, the supply voltage is 120
> volts, and the touch current limit is 0.5 mA, the Y1 and Y2 capacitance
> reactance is 238,000 ohms each. The Y2 capacitance is shunted by the
> 2,000-ohm resistor and can be ignored as the voltage across the Y2 and
> 2,000-ohm resistor is 1 volt.  (The current through the 238,000-ohm
> reactance is 4.2 microamps.)
>
>
>
> We have a parallel circuit to ground from the junction of Y1 and Y2 when
> the PE is open and when touch current is being measured.  One circuit to
> ground is through the touch current measuring circuit.  The other circuit
> to ground (via the N) is through the Y2 capacitor. If the Y2 reactance is
> small, a significant N current can be in that path to ground thereby
> reducing the touch current, not a partial cancel of the touch current.
>
>
>
> Best regards,
>
> Rich
>
>
>
>
>
> *From:* John Woodgate 
> *Sent:* Thursday, August 25, 2022 12:32 PM
> *To:* ri...@ieee.org; EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] High Touch Current and GFCIs
>
>
>
> There is also a question in my mind as to whether there can be partial
> cancellation of touch current. I suspect this is highly improbable in the
> US, due to the distribution system ensuring that the neutral has a very low
> voltage difference from the PEC. But in Europe, it's not inconceivable that
> the neutral could be, say, 4.6 V relative to PEC and the neutral-to-PEC
> capacitance 25 times that of L to PEC, so that half the L-to-PEC leakage
> current is cancelled by the N to PEC current.
>
>
> ==
> Best wishes John Woodgate OOO-Own Opinions Only
> www.woodjohn.uk
> Rayleigh, Essex UK
> It all depends
>
>
> On 2022-08-25 19:12, Richard Nute wrote:
>
>
>
>
>
> I wish to make two points:
>
>
>
>1. Kirchoff’s Current Law states that the sum of currents entering a
>node equals the sum of currents leaving the node.  The Law applies to
>summation of leakage (touch) currents (e.g., through a 2,000-ohm resistor)
>and to summation of protective conductor currents (through 0 ohms).  In a
>power strip protective grounding conductor, I’m assuming 0 ohms to ground,
>so the current is slightly higher (1 to 10 % depending on the leakage
>current limit and the voltage you are using) in the protective grounding
>conductor than leakage (touch) current.
>
>
>
> See IEC 60990 for touch (leakage) current and protective conductor current
> measurement procedures.
>
>
>
>1. A GFCI measures the current difference between line and neut

Re: [PSES] High Touch Current and GFCIs

[Brian Kunde]

When I run the Touch Current test and the EUT is not isolated from PE when
I press the Test Button that opens the PE conductor, the meter on the test
will max out. Sometimes it will even blow the fuse.  What is happening at
that point?  Am I reading the Touch Current from every piece of equipment
in the building?

Thanks,
The Other Brian

On Sat, Aug 27, 2022 at 6:38 PM Richard Nute  wrote:

>
>
> I wouldn’t describe the phenomenon as “cancellation.”  The touch current
> is always present and must have a path to earth/ground.
>
>
>
> The equivalent equipment circuit:
>
> Y1 capacitor L-(line)-to-PE.
>
> Y2 capacitor N-(neutral)-to-PE.  Capacitor value is 25x Y1 capacitor value.
>
> 4.6 volts N-to-(grounded)-PE.
>
>
>
> In the USA, N is connected to a ground rod at the building service
> entrance.  PE is connected to N at the breaker box.  In the building, PE is
> parallel to N, but is a non-current-carrying conductor except in the case
> of a fault.
>
>
>
> The Y1 and Y2 capacitors are in series and comprise a voltage divider to
> an open PE.  Because the Y2 capacitor is 25x the Y1 capacitor, the
> open-circuit voltage at the PE connection is very low compared the line
> voltage (instead of the usual half the line voltage).
>
>
>
> Normal condition touch current path is from L to Y1 to PE (open) to a
> 2,000-ohm resistor to ground,  Touch current is calculated using Ohm’s Law
> from the measured voltage across the 2,000-ohm resistor. The 2,000-ohm
> resistor is (in essence) parallel to the Y2 capacitor.  Some of the L-to-Y1
> current (not touch current!) returns to ground through the Y2-N-ground
> circuit, depending on the parallel network of capacitance reactance and the
> 2,000-ohm resistor.
>
>
>
> Reverse polarity (L and N reversed in the supply to the equipment) current
> path is N to Y2 to PE (open) to the 2,000-ohm resistor to ground.  Because
> Y2 is 25x Y1, the touch current is much higher than normal polarity.  As in
> the normal polarity condition, some of the current (very small) returns to
> ground through the Y1 capacitor.
>
>
>
> If the Y1 and Y2 capacitors are of equal value, the supply voltage is 120
> volts, and the touch current limit is 0.5 mA, the Y1 and Y2 capacitance
> reactance is 238,000 ohms each. The Y2 capacitance is shunted by the
> 2,000-ohm resistor and can be ignored as the voltage across the Y2 and
> 2,000-ohm resistor is 1 volt.  (The current through the 238,000-ohm
> reactance is 4.2 microamps.)
>
>
>
> We have a parallel circuit to ground from the junction of Y1 and Y2 when
> the PE is open and when touch current is being measured.  One circuit to
> ground is through the touch current measuring circuit.  The other circuit
> to ground (via the N) is through the Y2 capacitor. If the Y2 reactance is
> small, a significant N current can be in that path to ground thereby
> reducing the touch current, not a partial cancel of the touch current.
>
>
>
> Best regards,
>
> Rich
>
>
>
>
>
> *From:* John Woodgate 
> *Sent:* Thursday, August 25, 2022 12:32 PM
> *To:* ri...@ieee.org; EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] High Touch Current and GFCIs
>
>
>
> There is also a question in my mind as to whether there can be partial
> cancellation of touch current. I suspect this is highly improbable in the
> US, due to the distribution system ensuring that the neutral has a very low
> voltage difference from the PEC. But in Europe, it's not inconceivable that
> the neutral could be, say, 4.6 V relative to PEC and the neutral-to-PEC
> capacitance 25 times that of L to PEC, so that half the L-to-PEC leakage
> current is cancelled by the N to PEC current.
>
>
> ==
> Best wishes John Woodgate OOO-Own Opinions Only
> www.woodjohn.uk
> Rayleigh, Essex UK
> It all depends
>
>
> On 2022-08-25 19:12, Richard Nute wrote:
>
>
>
>
>
> I wish to make two points:
>
>
>
>1. Kirchoff’s Current Law states that the sum of currents entering a
>node equals the sum of currents leaving the node.  The Law applies to
>summation of leakage (touch) currents (e.g., through a 2,000-ohm resistor)
>and to summation of protective conductor currents (through 0 ohms).  In a
>power strip protective grounding conductor, I’m assuming 0 ohms to ground,
>so the current is slightly higher (1 to 10 % depending on the leakage
>current limit and the voltage you are using) in the protective grounding
>conductor than leakage (touch) current.
>
>
>
> See IEC 60990 for touch (leakage) current and protective conductor current
> measurement procedures.

Re: [PSES] High Touch Current and GFCIs

[Richard Nute]

 

I wouldn’t describe the phenomenon as “cancellation.”  The touch current is 
always present and must have a path to earth/ground.  

 

The equivalent equipment circuit:

Y1 capacitor L-(line)-to-PE. 

Y2 capacitor N-(neutral)-to-PE.  Capacitor value is 25x Y1 capacitor value.

4.6 volts N-to-(grounded)-PE.

 

In the USA, N is connected to a ground rod at the building service entrance.  
PE is connected to N at the breaker box.  In the building, PE is parallel to N, 
but is a non-current-carrying conductor except in the case of a fault. 

 

The Y1 and Y2 capacitors are in series and comprise a voltage divider to an 
open PE.  Because the Y2 capacitor is 25x the Y1 capacitor, the open-circuit 
voltage at the PE connection is very low compared the line voltage (instead of 
the usual half the line voltage).  

 

Normal condition touch current path is from L to Y1 to PE (open) to a 2,000-ohm 
resistor to ground,  Touch current is calculated using Ohm’s Law from the 
measured voltage across the 2,000-ohm resistor. The 2,000-ohm resistor is (in 
essence) parallel to the Y2 capacitor.  Some of the L-to-Y1 current (not touch 
current!) returns to ground through the Y2-N-ground circuit, depending on the 
parallel network of capacitance reactance and the 2,000-ohm resistor.

 

Reverse polarity (L and N reversed in the supply to the equipment) current path 
is N to Y2 to PE (open) to the 2,000-ohm resistor to ground.  Because Y2 is 25x 
Y1, the touch current is much higher than normal polarity.  As in the normal 
polarity condition, some of the current (very small) returns to ground through 
the Y1 capacitor.  

 

If the Y1 and Y2 capacitors are of equal value, the supply voltage is 120 
volts, and the touch current limit is 0.5 mA, the Y1 and Y2 capacitance 
reactance is 238,000 ohms each. The Y2 capacitance is shunted by the 2,000-ohm 
resistor and can be ignored as the voltage across the Y2 and 2,000-ohm resistor 
is 1 volt.  (The current through the 238,000-ohm reactance is 4.2 microamps.)

 

We have a parallel circuit to ground from the junction of Y1 and Y2 when the PE 
is open and when touch current is being measured.  One circuit to ground is 
through the touch current measuring circuit.  The other circuit to ground (via 
the N) is through the Y2 capacitor. If the Y2 reactance is small, a significant 
N current can be in that path to ground thereby reducing the touch current, not 
a partial cancel of the touch current.

 

Best regards,

Rich

 

 

From: John Woodgate  
Sent: Thursday, August 25, 2022 12:32 PM
To: ri...@ieee.org; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] High Touch Current and GFCIs

 

There is also a question in my mind as to whether there can be partial 
cancellation of touch current. I suspect this is highly improbable in the US, 
due to the distribution system ensuring that the neutral has a very low voltage 
difference from the PEC. But in Europe, it's not inconceivable that the neutral 
could be, say, 4.6 V relative to PEC and the neutral-to-PEC capacitance 25 
times that of L to PEC, so that half the L-to-PEC leakage current is cancelled 
by the N to PEC current.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk <http://www.woodjohn.uk> 
Rayleigh, Essex UK
It all depends




On 2022-08-25 19:12, Richard Nute wrote:

 

 

I wish to make two points:

 

1.  Kirchoff’s Current Law states that the sum of currents entering a node 
equals the sum of currents leaving the node.  The Law applies to summation of 
leakage (touch) currents (e.g., through a 2,000-ohm resistor) and to summation 
of protective conductor currents (through 0 ohms).  In a power strip protective 
grounding conductor, I’m assuming 0 ohms to ground, so the current is slightly 
higher (1 to 10 % depending on the leakage current limit and the voltage you 
are using) in the protective grounding conductor than leakage (touch) current. 

 

See IEC 60990 for touch (leakage) current and protective conductor current 
measurement procedures.  

 

2.  A GFCI measures the current difference between line and neutral 
conductors, not current in the protective conductor.  It nominally operates at 
5 mA.  We assume (with a reasonable degree of accuracy) that leakage (touch) 
current is 100% of the differential current measured by the GFCI.  It is 
possible, although unlikely, for some of the GFCI differential current to find 
another return path than the protective grounding conductor.

Best regards,

Rich

 

 

From: Lfresearch Jose  
<mailto:00734758d943-dmarc-requ...@listserv.ieee.org> 
<00734758d943-dmarc-requ...@listserv.ieee.org> 
Sent: Wednesday, August 24, 2022 1:44 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: Re: [PSES] High Touch Current and GFCIs

 

I have wondered about something similar.

 

If I use a 6 way power strip, I’m 

Re: [PSES] High Touch Current and GFCIs

[John Woodgate]

Good point.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK
It all depends



On 2022-08-26 17:02, Don Gies wrote:


The cancellation that Mr. Woodgate points out could occur with 
industrial equipment that was powered from North American  120/240 V 
ac, 3-wire single phase or 240 Vac, single phase circuits (where there 
are two line conductors separated in phase by 180 degrees on a 
center-tapped, single-phase distribution transformer) or from 208 Vac, 
single-phase equipment  (where the two line conductors are separated 
in phase by 120 degrees on a 3-phase distribution transformer).


If your market was strictly North America, you might use this to your 
advantage.  It is likely, though, that such equipment is sold on the 
global market, so you might test for touch current with a 230 V, 
single phase input (that is, 230V to earthed neutral).  Then, no such 
cancellation of touch current.


Best regards,

*Don Gies*


Internal

*From:*John Woodgate 
*Sent:* Thursday, August 25, 2022 3:32 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] High Touch Current and GFCIs

[External email: Use caution with links and attachments]



There is also a question in my mind as to whether there can be partial 
cancellation of touch current. I suspect this is highly improbable in 
the US, due to the distribution system ensuring that the neutral has a 
very low voltage difference from the PEC. But in Europe, it's not 
inconceivable that the neutral could be, say, 4.6 V relative to PEC 
and the neutral-to-PEC capacitance 25 times that of L to PEC, so that 
half the L-to-PEC leakage current is cancelled by the N to PEC current.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk 
<https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk%2F=05%7C01%7Cdonald.gies%40se.com%7C7046b051e9cd42fd084908da86d07966%7C6e51e1adc54b4b39b5980ffe9ae68fef%7C0%7C0%7C637970527292966147%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=YTPpuf0fmAT3zFhO2daPXwkAknmm000tpUrSpv941i8%3D=0>

Rayleigh, Essex UK
It all depends

On 2022-08-25 19:12, Richard Nute wrote:

I wish to make two points:

 1. Kirchoff’s Current Law states that the sum of currents
entering a node equals the sum of currents leaving the node. 
The Law applies to summation of leakage (touch) currents
(e.g., through a 2,000-ohm resistor) and to summation of
protective conductor currents (through 0 ohms).  In a power
strip protective grounding conductor, I’m assuming 0 ohms to
ground, so the current is slightly higher (1 to 10 % depending
on the leakage current limit and the voltage you are using) in
the protective grounding conductor than leakage (touch) current.

See IEC 60990 for touch (leakage) current and protective conductor
current measurement procedures.

 2. A GFCI measures the current difference between line and
neutral conductors, not current in the protective conductor. 
It nominally operates at 5 mA.  We assume (with a reasonable
degree of accuracy) that leakage (touch) current is 100% of
the differential current measured by the GFCI.  It is
possible, although unlikely, for some of the GFCI differential
current to find another return path than the protective
grounding conductor.

Best regards,

Rich

*From:* Lfresearch Jose
<00734758d943-dmarc-requ...@listserv.ieee.org>
<mailto:00734758d943-dmarc-requ...@listserv.ieee.org>
*Sent:* Wednesday, August 24, 2022 1:44 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
    *Subject:* Re: [PSES] High Touch Current and GFCIs

I have wondered about something similar.

If I use a 6 way power strip, I’m assuming all the leakage
currents for anything plugged in sum. Is that correct? I recall
getting a few trips when I used a power strip and It’s only just
twigged that might be why.

Cheers,

Derek.

Sent from my iPad



On Aug 24, 2022, at 3:27 PM, Brian Kunde
 wrote:



If I have a rake of electrical equipment with a single power
cord and a combined touch current exceeding 6mA, and I plug
the rake into a circuit with a GFCI, will it trip?

Thanks.

The Other Brian

-


This message is from the IEEE Product Safety Engineering
Society emc-pstc discussion list. To post a message to the
list, send your e-mail to 

All emc-pstc postings are archived and searchable on the we

Re: [PSES] High Touch Current and GFCIs

[Don Gies]

The cancellation that Mr. Woodgate points out could occur with industrial 
equipment that was powered from North American  120/240 V ac, 3-wire single 
phase or 240 Vac, single phase circuits (where there are two line conductors 
separated in phase by 180 degrees on a center-tapped, single-phase distribution 
transformer) or from 208 Vac, single-phase equipment  (where the two line 
conductors are separated in phase by 120 degrees on a 3-phase distribution 
transformer).

If your market was strictly North America, you might use this to your 
advantage.  It is likely, though, that such equipment is sold on the global 
market, so you might test for touch current with a 230 V, single phase input 
(that is, 230V to earthed neutral).  Then, no such cancellation of touch 
current.

Best regards,

Don Gies




Internal
From: John Woodgate 
Sent: Thursday, August 25, 2022 3:32 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] High Touch Current and GFCIs


[External email: Use caution with links and attachments]





There is also a question in my mind as to whether there can be partial 
cancellation of touch current. I suspect this is highly improbable in the US, 
due to the distribution system ensuring that the neutral has a very low voltage 
difference from the PEC. But in Europe, it's not inconceivable that the neutral 
could be, say, 4.6 V relative to PEC and the neutral-to-PEC capacitance 25 
times that of L to PEC, so that half the L-to-PEC leakage current is cancelled 
by the N to PEC current.
==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk<https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk%2F=05%7C01%7Cdonald.gies%40se.com%7C7046b051e9cd42fd084908da86d07966%7C6e51e1adc54b4b39b5980ffe9ae68fef%7C0%7C0%7C637970527292966147%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=YTPpuf0fmAT3zFhO2daPXwkAknmm000tpUrSpv941i8%3D=0>
Rayleigh, Essex UK
It all depends

On 2022-08-25 19:12, Richard Nute wrote:


I wish to make two points:


  1.  Kirchoff’s Current Law states that the sum of currents entering a node 
equals the sum of currents leaving the node.  The Law applies to summation of 
leakage (touch) currents (e.g., through a 2,000-ohm resistor) and to summation 
of protective conductor currents (through 0 ohms).  In a power strip protective 
grounding conductor, I’m assuming 0 ohms to ground, so the current is slightly 
higher (1 to 10 % depending on the leakage current limit and the voltage you 
are using) in the protective grounding conductor than leakage (touch) current.

See IEC 60990 for touch (leakage) current and protective conductor current 
measurement procedures.



  1.  A GFCI measures the current difference between line and neutral 
conductors, not current in the protective conductor.  It nominally operates at 
5 mA.  We assume (with a reasonable degree of accuracy) that leakage (touch) 
current is 100% of the differential current measured by the GFCI.  It is 
possible, although unlikely, for some of the GFCI differential current to find 
another return path than the protective grounding conductor.
Best regards,
Rich


From: Lfresearch Jose 
<00734758d943-dmarc-requ...@listserv.ieee.org><mailto:00734758d943-dmarc-requ...@listserv.ieee.org>
Sent: Wednesday, August 24, 2022 1:44 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] High Touch Current and GFCIs

I have wondered about something similar.

If I use a 6 way power strip, I’m assuming all the leakage currents for 
anything plugged in sum. Is that correct? I recall getting a few trips when I 
used a power strip and It’s only just twigged that might be why.

Cheers,

Derek.
Sent from my iPad


On Aug 24, 2022, at 3:27 PM, Brian Kunde 
mailto:bkundew...@gmail.com>> wrote:

If I have a rake of electrical equipment with a single power cord and a 
combined touch current exceeding 6mA, and I plug the rake into a circuit with a 
GFCI, will it trip?

Thanks.

The Other Brian
-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html<https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=05%7C01%7Cdonald.gies%40se.com%7C7046b051e9cd42fd084908da86d07966%7C6e51e1adc54b4b39b5980ffe9ae68fef%7C0%7C0%7C637970527292966147%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=iOWJbGDVA2VIgouaMohdShgvwFzojuN1gl1ubfZXDkU%3D=0>

Website: 
http://www.ieee-pses.org/<https://eur

Re: [PSES] High Touch Current and GFCIs

[John Woodgate]

There is also a question in my mind as to whether there can be partial 
cancellation of touch current. I suspect this is highly improbable in 
the US, due to the distribution system ensuring that the neutral has a 
very low voltage difference from the PEC. But in Europe, it's not 
inconceivable that the neutral could be, say, 4.6 V relative to PEC and 
the neutral-to-PEC capacitance 25 times that of L to PEC, so that half 
the L-to-PEC leakage current is cancelled by the N to PEC current.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK
It all depends



On 2022-08-25 19:12, Richard Nute wrote:


I wish to make two points:

 1. Kirchoff’s Current Law states that the sum of currents entering a
node equals the sum of currents leaving the node.  The Law applies
to summation of leakage (touch) currents (e.g., through a
2,000-ohm resistor) and to summation of protective conductor
currents (through 0 ohms).  In a power strip protective grounding
conductor, I’m assuming 0 ohms to ground, so the current is
slightly higher (1 to 10 % depending on the leakage current limit
and the voltage you are using) in the protective grounding
conductor than leakage (touch) current.

See IEC 60990 for touch (leakage) current and protective conductor 
current measurement procedures.


 2. A GFCI measures the current difference between line and neutral
conductors, not current in the protective conductor.  It nominally
operates at 5 mA.  We assume (with a reasonable degree of
accuracy) that leakage (touch) current is 100% of the differential
current measured by the GFCI.  It is possible, although unlikely,
for some of the GFCI differential current to find another return
path than the protective grounding conductor.

Best regards,

Rich

*From:* Lfresearch Jose 
<00734758d943-dmarc-requ...@listserv.ieee.org>

*Sent:* Wednesday, August 24, 2022 1:44 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] High Touch Current and GFCIs

I have wondered about something similar.

If I use a 6 way power strip, I’m assuming all the leakage currents 
for anything plugged in sum. Is that correct? I recall getting a few 
trips when I used a power strip and It’s only just twigged that might 
be why.


Cheers,

Derek.

Sent from my iPad



On Aug 24, 2022, at 3:27 PM, Brian Kunde  wrote:



If I have a rake of electrical equipment with a single power cord
and a combined touch current exceeding 6mA, and I plug the rake
into a circuit with a GFCI, will it trip?

Thanks.

The Other Brian

-


This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. To post a message to the list, send your
e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to
unsubscribe) <http://www.ieee-pses.org/list.html>
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher 
David Heald 



To unsubscribe from the EMC-PSTC list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1
<https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1>

-


This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your 
e-mail to 


All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html


Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to 
unsubscribe) <http://www.ieee-pses.org/list.html>

List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher 
David Heald 



To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1 
<https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1>


-


This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your 
e-mail to 


All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html


Website: http://www.ieee-pses.org/
Instruct

Re: [PSES] High Touch Current and GFCIs

[Richard Nute]

 

 

I wish to make two points:

 

1.  Kirchoff’s Current Law states that the sum of currents entering a node 
equals the sum of currents leaving the node.  The Law applies to summation of 
leakage (touch) currents (e.g., through a 2,000-ohm resistor) and to summation 
of protective conductor currents (through 0 ohms).  In a power strip protective 
grounding conductor, I’m assuming 0 ohms to ground, so the current is slightly 
higher (1 to 10 % depending on the leakage current limit and the voltage you 
are using) in the protective grounding conductor than leakage (touch) current. 

 

See IEC 60990 for touch (leakage) current and protective conductor current 
measurement procedures.  

 

2.  A GFCI measures the current difference between line and neutral 
conductors, not current in the protective conductor.  It nominally operates at 
5 mA.  We assume (with a reasonable degree of accuracy) that leakage (touch) 
current is 100% of the differential current measured by the GFCI.  It is 
possible, although unlikely, for some of the GFCI differential current to find 
another return path than the protective grounding conductor.

Best regards,

Rich

 

 

From: Lfresearch Jose <00734758d943-dmarc-requ...@listserv.ieee.org> 
Sent: Wednesday, August 24, 2022 1:44 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] High Touch Current and GFCIs

 

I have wondered about something similar.

 

If I use a 6 way power strip, I’m assuming all the leakage currents for 
anything plugged in sum. Is that correct? I recall getting a few trips when I 
used a power strip and It’s only just twigged that might be why.

 

Cheers,

 

Derek.

Sent from my iPad





On Aug 24, 2022, at 3:27 PM, Brian Kunde mailto:bkundew...@gmail.com> > wrote:



If I have a rake of electrical equipment with a single power cord and a 
combined touch current exceeding 6mA, and I plug the rake into a circuit with a 
GFCI, will it trip?  

 

Thanks.

 

The Other Brian

-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org> >

All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html

Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 
<http://www.ieee-pses.org/list.html> 
List rules: http://www.ieee-pses.org/listrules.html 

For help, send mail to the list administrators:
Mike Cantwell mailto:mcantw...@ieee.org> > 

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org> >
David Heald mailto:dhe...@gmail.com> > 

  _  

To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC 
<https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1> =1 

-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org> >

All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html

Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 
<http://www.ieee-pses.org/list.html> 
List rules: http://www.ieee-pses.org/listrules.html 

For help, send mail to the list administrators:
Mike Cantwell mailto:mcantw...@ieee.org> > 

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org> >
David Heald mailto:dhe...@gmail.com> > 

  _  

To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC 
<https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1> =1 


-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
_
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

Re: [PSES] High Touch Current and GFCIs

[Douglas E Powell]

Brian,

Depending on the class of that circuit breaker, the answer is probably
yes.  See this article


Sometimes when dealing with high leakage current the relevant safety
standard allows you to go to a much higher level if you provide secondary
chassis grounding (earthing) and a warning label. Of course, this all
depends on how the product is configured. Check for this provision in the
safety standard you are using.

This may be a case where your rack system has multiple devices, each with
their own EMI line filter.  And the "Y" caps in all the line filters add up
to a larger contribution of leakage current.  One option might be to remove
the individual filters (if possible) and provide a single low-leakage EMI
filter on the rack power inlet.  Alternatively you could entertain the idea
often used on equipment that requires very low leakage current in the 50 uA
range.  That is, an approved isolation transformer built into the rack
power distribution.

-Doug


Douglas E Powell
Laporte, Colorado USA
LinkedIn 

(UTC -06:00) Mountain Time (US-MDT)


On Wed, Aug 24, 2022 at 2:27 PM Brian Kunde  wrote:

> If I have a rake of electrical equipment with a single power cord and a
> combined touch current exceeding 6mA, and I plug the rake into a circuit
> with a GFCI, will it trip?
>
> Thanks.
>
> The Other Brian
> -
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to 
> emc-p...@ieee.org
>
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
>
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe) 
> List rules: http://www.ieee-pses.org/listrules.html
>
> For help, send mail to the list administrators:
> Mike Cantwell mcantw...@ieee.org
>
> For policy questions, send mail to:
> Jim Bacher j.bac...@ieee.org
> David Heald dhe...@gmail.com
> --
>
> To unsubscribe from the EMC-PSTC list, click the following link:
> https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1
>

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
_
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

Re: [PSES] [EXTERNAL] [PSES] High Touch Current and GFCIs

[Ted Eckert]

Hi Brian,

Yes, it will trip. I have even worse news for you. It may trip if your touch 
current is less than 5 mA. We use the human body model for touch current 
measurement, and it's frequency limited. I had a product that was less than 1.5 
mA touch current when measured with IEC 60990 methods, but it measured 9 mA 
when measured by a meter that went up to 100 kHz frequency response. There was 
a lot of high-frequency current blocked by the touch current network. However, 
the product regularly tripped GFCIs, since GFCIs don't necessarily have a 
low-pass filter.

The Y-caps on many IT product power supplies might allow current at higher 
frequencies onto the ground which could trip GFCIs. Plug a bunch of IT products 
into the same GFCI circuit, and the risk of nuisance tripping goes up.

Ted Eckert
The opinions expressed are my own and do not necessarily reflect those of my 
employer.

From: Brian Kunde 
Sent: Wednesday, August 24, 2022 1:27 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [EXTERNAL] [PSES] High Touch Current and GFCIs

If I have a rake of electrical equipment with a single power cord and a 
combined touch current exceeding 6mA, and I plug the rake into a circuit with a 
GFCI, will it trip?

Thanks.

The Other Brian
-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=05%7C01%7Cted.eckert%40microsoft.com%7Cff2f9a7566f64b29dcdf08da860f12f3%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637969696549312115%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=Fa3Vt2WI4ejMxVeKFsMNjPdNsfEMMC0AT%2BKrNQIzwWY%3D=0>

Website: 
http://www.ieee-pses.org/<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2F=05%7C01%7Cted.eckert%40microsoft.com%7Cff2f9a7566f64b29dcdf08da860f12f3%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637969696549312115%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=SNjI39rCns7DirWXDdhMLJTjWOj1p%2Feu%2BGBDcZcMvjA%3D=0>
Instructions: http://www.ieee-pses.org/list.html (including how to 
unsubscribe)<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flist.html=05%7C01%7Cted.eckert%40microsoft.com%7Cff2f9a7566f64b29dcdf08da860f12f3%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637969696549312115%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=O2TweDV12aSXphuk1F3qF%2FxKpBaTTeFrXKAXQO%2FKkQM%3D=0>
List rules: 
http://www.ieee-pses.org/listrules.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flistrules.html=05%7C01%7Cted.eckert%40microsoft.com%7Cff2f9a7566f64b29dcdf08da860f12f3%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637969696549312115%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=KMHJdwsE8GiuKJzHVUY73aWQj%2FetJy7ZpoV%2BT0%2Bu%2Fi4%3D=0>

For help, send mail to the list administrators:
Mike Cantwell mailto:mcantw...@ieee.org>>

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org>>
David Heald mailto:dhe...@gmail.com>>



To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
_
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

Re: [PSES] High Touch Current and GFCIs

[Lfresearch Jose]

I have wondered about something similar.

If I use a 6 way power strip, I’m assuming all the leakage currents for 
anything plugged in sum. Is that correct? I recall getting a few trips when I 
used a power strip and It’s only just twigged that might be why.

Cheers,

Derek.

Sent from my iPad

> On Aug 24, 2022, at 3:27 PM, Brian Kunde  wrote:
> 
> 
> If I have a rake of electrical equipment with a single power cord and a 
> combined touch current exceeding 6mA, and I plug the rake into a circuit with 
> a GFCI, will it trip?  
> 
> Thanks.
> 
> The Other Brian
> -
> 
> This message is from the IEEE Product Safety Engineering Society emc-pstc 
> discussion list. To post a message to the list, send your e-mail to 
> 
> 
> All emc-pstc postings are archived and searchable on the web at: 
> http://www.ieee-pses.org/emc-pstc.html
> 
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to 
> unsubscribe)
> List rules: http://www.ieee-pses.org/listrules.html
> 
> For help, send mail to the list administrators:
> Mike Cantwell 
> 
> For policy questions, send mail to:
> Jim Bacher 
> David Heald 
> 
> To unsubscribe from the EMC-PSTC list, click the following link: 
> https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
_
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1

[PSES] High Touch Current and GFCIs

[Brian Kunde]

If I have a rake of electrical equipment with a single power cord and a
combined touch current exceeding 6mA, and I plug the rake into a circuit
with a GFCI, will it trip?

Thanks.

The Other Brian

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
_
To unsubscribe from the EMC-PSTC list, click the following link: 
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC=1