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,



From: Brian Kunde <bkundew...@gmail.com> 
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?



The Other Brian


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