GFCI outlet trip time

Many believe it is more accurate if its digital. Not so. Digital just means it has better resolution, accuracy could be out to lunch but you’ll think you have an exact measurement.
8-25-03badmood

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I was actively training apprentice electricians when the digital meters started to become popular. The digital meters made my job a little harder. I had to start going deeper into electrical theory and not how electronics work so that the electricians could understand how to interpret the readings on digital meters.

Most electricians trained after the early 1980s do not have good troubleshooting skills. Electrical apprenticeships were expanded from four years to five because of new and emerging technologies, but they stop short of going deep enough into how electricity works for younger electricians to develop good troubleshooting skills.

I expect that future electrical apprenticeship programs will go deeper into electrical theory and electronics. I had an advantage because I was a self-taught serious electronics hobbyist long before I got into the electrical trades. The difference was clear to me during my apprentice. Many of my fellow apprentices struggled with basic electrical concepts.

Later in my career, when I had the opportunity to help develop apprenticeship programs, I pushed for more electrical theory and electronics and an emphasis on developing troubleshooting skills. I also advocated for not putting too much emphasis on model codes such as the NEC until after the apprentices demonstrated a good basic understanding of electricity and electrical systems.

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Morning, George.
The accuracy of the instrument is not in question. From the manufacturer.
Range and Resolution Accuracy:
Line Voltage (Single phase) 100.0 to 250.0 VAC ± (1.0% + 0.2V)
Peak Line Voltage 121.0 to 350.0 VAC ± (1.0% + 0.2V)
Frequency 45.0 to 65.0 Hz ± (1.0% + 0.2Hz)
Voltage drop (%) 0.1 to 99.9% ± (2.5% + 0.2%)
Voltage (under load) 10.0 to 250.0 VAC ± (2.5% + 0.2V)
Neutral to Ground Voltage 0.0 to 10.0 VAC ± (2.5% + 0.2V)
Impedance
0.00 to 3.00 Ω (Hot) ± (2.5% + 0.02Ω)

3 Ω (Neutral, Ground) Unspecified
GFCI Trip Current 6.0 to 9.0mA ± (1.0% + 0.2mA)
EPD Trip Current 30.0 to 37.0mA ± (1.0% + 0.2mA)

31.7 mA is above the 5-6mA threshold yet the equipment tripped. The screen remained blue, it turns red when there is an issue or goes blank.
Is replacement of the GFI recommended?

It functioned properly with the test button so no the GFCI does not need to be replaced. From reading the Extech manual it sounds like you set the GFCI test to the incorrect test parameter. You can toggle between GFCI and EPD which is the two different mA settings. Not sure why Extech uses EPD when the correct term from the NEC is GFPE.

From the user manual:
GFCI Button
The GFCI (Ground Fault Circuit Interrupt) feature performs two tests:
GFCI: Faults a circuit when 6 to 9mA from hot to ground is detected
EPD (Equipment Protective Device): For breakers equipped with an EPD, the breaker trips for
ground faults greater than 30mA.
To display the GFCI main menu window, press the GFCI button. To toggle the two tests use the ►
button. Once the desired test is selected, press the GFCI button to start the test. These tests are
further detailed below.

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The problem with high input-impedance meters is that they can give false readings and too many users lack a basic understanding of electricity so they don’t know how to interpret what they find with the meters.

In the case of a GFCI the measured trip times are almost completely meaningless. There are many variables that will determine the trip time in an actual ground fault. The best way to test a GFCI is to use the test button.

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We are talking about a $20 GFCI receptacle being a bit slow to respond and at a slightly higher amperage than recommended. Just report what you observed. I would suggest that you recommend that the homeowner consider replacing it, because it could be deteriorating and fail to trip at all in the future. I would also point out the expected life expectancy of a GFCI receptacle, which generally falls into the 10 to 20 year range.

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A whole useless thread based on operator error! Once a WAFI always a WAFI!

Don’t replace the GFCI, get a real inspector!

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I agree Bob, if the receptacle test button showed that the GFCI performed as required why would you someone think that you needed to replace the device. It seems to me from reading the user manual that the test device was set to the wrong scale.

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GFPE (Ground-Fault Protection of Equipment) GFPE protection used for protecting equipment will trip at 30mA.
The Differences between GFCI, IDCI, and GFPE
Interesting discussion and how some inspectors reacted.

This sums it up!

I disagree.
Where the GFCI is required to provide ‘protection’ for personnel, the level must be above 4 milliamperes but not more than 6 milliamperes and must operate within a time-frame of 'less than 25 milliseconds.
A ground fault circuit interrupter (GFCI) breaks the fault current. The GFCI is designed to open the circuit, or a portion of the circuit to a load, within a predetermined value. This value must be less than the current level required to operate the overcurrent protective device of the circuit.
Best Practices-How Ground Fault Detection and Protection Requirements Protect People and Equipment
The most widespread use of the Class A GFCI is for receptacles located near water or the earth. The Canadian Electrical Code requires that a Class A GFCI be provided to protect all receptacles within 1.5 meters of a sink.
As well, outlets above counters used to prepare food and beverages

So to sum up this entire thread, if the GFCI trips when it is supposed to, that doesn’t mean it works!

We now have to apply testing down to millivolts and milliseconds, using only equipment that is approved by a majority of our peers for fear of being called out for substandard equipment!

How about: The GFCI works as intended folks - nothing to see here, move along!

Any complaints about the milli-level operation of these devices would be better suited on the web pages of those device manufacturers. This website deals with (gasp!) home inspections!

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image

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:rofl: :rofl: :rofl: :rofl: :rofl::rofl: :rofl: :rofl: :rofl: :rofl::rofl: :rofl: :rofl: :rofl: :rofl::rofl: :rofl: :rofl: :rofl: :rofl:
Exactly!

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Gave these to all my kids to teach them about electrical currents and how to deal with them in the future. :stuck_out_tongue_winking_eye:

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If you plugged that in would the GFCI receptacle trip?

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It should if you are grounded, right?

Matbe not, but the breaker should after it burns your finger off!

That’s exactly what was done in this case, it’s right in the OP’s pic:

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PS: I had multiple CT70s and got rid of them because they couldn’t test the wiring correctly in some instances – the support is clueless, they just kept sending me the same malfunctioning model in a new unit. So I gave up and got rid of them – they don’t really care about this tester.

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Thanks Simon. I was hoping that someone with hands on knowledge of this tester would respond. The fact that it worked normally with the test button would be indicative of an incorrect testing method using the CT70 tester.

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