GFCI Pickle Plug

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From: DonRath@aol.com
Date: Sat Apr 15 2000 - 13:13:32 PDT 

From: DonRath@aol.com
Message-ID: <30.3cb3037.262a276c@aol.com>
Date: Sat, 15 Apr 2000 16:13:32 EDT
Subject: GFCI Pickle Plug

r.e. GFCI Pickle Plug
Pinhole Digest #391, 4/15/2000

Eric --

Good question about how the GFCI knows to turn off for the person, but not
the pickle. When the pickle is the only thing in the circuit, the amount of
current leaving the outlet to go to the pickle is the same as the amount
coming back from the pickle. The GFCI keeps track of this. If you touch the
pickle or other part of the circuit, and current goes through you to ground,
the GFCI detects that there is a "leakage" in the circuit and shuts if off.
It's not the total amount of current present that activates the GFCI
(overload problems are handled by the normal circuit breaker), but rather the
LOSS of current. Thus the fact that you have more resistance than the pickle
isn't the issue -- the GFCI isn't comparing you to the pickle, but rather
it's concerned about the fact that you have provided a path to ground which
drains current from the circuit.

Here are some interesting quotes from various sources ( boxes that the
outlets come in, accompanying instruction sheets, home wiring books, etc.):

"How does a Ground Fault Circuit Interrupter Work? The Ground Fault Circuit
Interrupter detects leakage current flowing to the ground. When the sensor
detects 4-6 milliamps of leakage, it automatically turns off the power fast
enough to help prevent injury to any adult in normal health. Leakage greater
than 200 milliamps can be fatal."

"Current leakage between 5 and 15 milliamps can cause muscle contractions
strong enough to prevent release of a faulty appliance."

"Ground Fault Circuit Interrupter (GFCI). A safety circuit breaker that
compares the amount of current entering a receptacle with the amount leaving.
If there is a discrepancy of 0.005 volt, the GFCI breaks the circuit in 1/40
of a second. Usually required by code in areas that are subject to dampness."

"WARNING: The GFCI will NOT protect against:
• Line-to-line shocks like the kind gotten by touching metal inserted in both
straight slots of an outlet.
• Current overloads or line-to-line short circuits; the fuse or circuit
breaker at the distribution box or panel must provide such protection."

Hope all this helps answer your question.

Don Rathjen

   

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