GFCI Chatter
Wenatchee Home Inspections
As a home inspector in Wenatchee, as required by our Standards of Practice, I am to test and report any failed or missing GFCI devices or protection as required by industry standards.
From the Washington State Standards of practice for home inspections-
https://apps.leg.wa.gov/WAC/default.aspx?cite=308-408C-110
WAC 308-408C-110
Electrical system.
The inspection of the electrical system includes the service drop through the main panel; subpanels including feeders; branch circuits, connected devices, and lighting fixtures.
(1) The inspector will:
(e) Verify
(iii) Ground fault circuit interrupter (GFCI) protection and arc-fault circuit interrupter (AFCI) protection where required.
(f) Report the location of any inoperative or missing GFCI and/or AFCI devices when they are recommended by industry standards.
(g)
Advise clients that homes without ground fault protection should have GFCI devices installed where recommended by industry standards.
Older GFCI Device
Since I am testing some of these devices I have started to notice a few odd occurrences with these devices, which I refer to as chatter.
What is happening when I test the device I hear a chatter that is occuring in the device and a delay in the device tripping as it is designed to do.
I have talked to several electricians about this and no one seems to know what is going on. My guess from seeing this on several GFCI receptacles that I have tested is that the solenoid and contacts are not opening as they should.
These devices are designed to open when there is a current imbalance between the hot and neutral conductors that creates an electromagnetic field that is detected via the sensing toroid coil.
In the GFCI there is a chip that controls the current that was generated from the toroids that is processed (by chip sets) and sends a signal to the solenoid that opens the circuit.
This is where I think the failure is occurring that the solenoid and contacts are not opening as they should.
What I did not know, and most likely many do not, is that there is also a second sensing toroid on these GFCI devices. This is to sense the current on the ground to neutral.
From the manufacturer:
“One point of confusion among some online commenters is how current can flow in the ground lead without causing a difference in the hot/neutral current that the first toroid would sense.
The answer: One can envision a scenario in which current flows from hot to load, then to neutral, and then to ground. There would potentially be no difference in the line and neutral current. So the GFCI circuit must sense this fault current with the operating assumption that the hot and neutral currents are the same.”
I have found that by pressing the test button and testing with my 3 bulb several times that on some GFCI's with small amounts of chatter you can get them to seemly to start working properly again.
This is a great reason to actually test these older GFCI's regularly or better yet be replaced with the newer devices. When I see this condition I write up that the device may be starting to fail.
Effective June 29, 2015, ground fault circuit interrupter (GFCI) receptacles and circuit breakers were required to be manufactured with an auto monitoring or self-test function. This requirement is another step in the continuous improvement of the Standard for Safety for Ground-Fault Circuit Interrupters, UL 943.
Since the newer GFCI's are designed to self test I feel they can provide a greater safety factor. It will be interesting to see if this chatter will happen on these self-testing devices or they just show up as failed.
Video from NCW Home Inspections-
https://www.youtube.com/watch?v=o5gvSuglvso
GFCI Auto Trip Comment-
https://iaeimagazine.org/magazine/columns/ul-question-corner/ul-question-corner-self-testing-gfci-requirements/
Here is another great video on GFCI and how they work
Teardown: Leviton Ground fault circuit interrupter
Article Link for the teardown video- GFCI Teardown
https://www.eeworldonline.com/teardown-leviton-ground-fault-circuit-interrupter/
“Invention is the most important product of man's creative brain.
The ultimate purpose is the complete mastery of mind over the material world,
the harnessing of human nature to human needs.”
Nikola Tesla
If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.
NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…
Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service
Instructor- Fundamentals of Home Inspection- Bellingham Technical College
WA Home Inspector Advisory Licensing Board
www.ncwhomeinspections.com 509-670-9572
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