You are correct about just being a differential current measurement.  But 20mA is deadly.  The trip point is typically around 5mA.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Drew meyer
Sent: Friday, June 07, 2013 2:19 PM
To: [log in to unmask]
Subject: Re: [TN] Hipot Testing

Hello,

Perhaps I am wrong but I will speak up.  My understanding of a GFI device was that it compared the currents in the hot lead and the nuetral lead.  As long as the two were the same all is well.  If the two are different that means that some of the current flowing through the hot lead is not returning through the neutral, an unacceptable condition as the path could be through a human body.  The differential trigger point was around 20mA.

Drew Meyer 

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