Hello everyone! My question today is about GFCI trip time. I have a new GFCI tester (Klein Tools RT250) and want to know the acceptable trip limits for a GFCI. I’ve misplaced the booklet, and I wonder if anyone could tell me when a GFCI outlet is taking too long to disrupt the power.
You are opening a can of worms. The UL testing has limits, but I believe it is not something you could detect with your push-button device. The manufacturer-approved method for testing GFCI is using the built-in test button on the receptacle or breaker. Personally, I have been tricked by the delay, but I do not consider it a defect.
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100 milliseconds or about 5 cycles at 60hz.
If if doesn’t trip immediately on your RT250, press the button on the device whether in the wall or the main panel.
A ground fault that is high resistance can take some time(up to 5 seconds or so), but a low resistance fault is a threat to human health and those test buttons are testing for that.
I have tested thousands of these things over the past 25 years or so, if they don’t trip immediately recommend replacement and call it out as a safety hazard.
I have never found a working one that doesn’t trip immediately. I realize the can of worms Brian is mentioning and ideally you should test on the device itself. The button is a fairly good proxy though. If you want to test downstream, it’s useful for that.
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Thanks, Mark and Brian, for your responses. I appreciate it. I love this forum, and members like you make it worthwhile. Now, I will test the outlet button on the receptacle and use the Klein tester simultaneously. The GFCI must trip quickly and immediately to protect people. If not, it’s going on in my inspection report.
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Do you call out a delay as a defect when using your RT250? And what does ‘immediately’ mean?
From the interweb lol…
T = (20/I)^1.43where I is in mA. From that equation, 20mA can take 1 second, 15mA can take 1.5 seconds, and 6mA can take 5.6 seconds.
I checked my tester and it has a 18 kOhm resister for 6.7mA so it can take almost 5 seconds to trip per code.
Here is another source from Mike Holt Forum
I have found this a few times in new construction.
UL943 is the spec for GFCI’s. It does specify maximum time for a GFCI to open as
where I is in mA. From that equation, 20mA can take 1 second, 15mA can take 1.5 seconds, and 6mA can take 5.6 seconds.
Did you just copy and paste that from my post directly above? Sheesh, lol
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The instruction manual is easily available here:
https://www.standardelectricco.com/1150253/product/n/klein-tools-klert250
and suggests that there is a problem with the GFCI if the trip time >6 seconds. To my mind this is a worthless test and it is quite probably that the circuitry inside the tester (RT250) is incapable of measuring time with any degree of accuracy. You get what you pay for and this is hardly lab grade equipment.
IMO you are asking for trouble if you make any more than basic recommendations about any outlet or GFCI. It can be miswired, inoperable (gfci-doesn’t trip), won’t reset (GFCI), or open. Anything beyond this is the domain of the electrician and is sure to cause client, seller, agent controversy or misunderstanding.
You can add improperly installed to the above and there are lots of variations of that descriptor!
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If I get a delay on the rt250, which, I don’t usually use, but if for whatever reason I were to get a delay on the RT250, I’ll try the button. No, I wouldn’t call out a defect unless I’m testing with the button on the device. That said, I’ve never found a discrepancy between the RT250 and the device itself. I’m not saying it doesn’t happen, I’ve never had it happen.
Also, to be clear, I’ve only had the RT250 for about 2 years now as I’ve worked as an inspector. When I was installing this stuff industrially, we rarely had a tester just the button on the device. One of the guys had one and I just sorta never really paid any attention to it because I had a way of testing the GFCIs once installed.
Immediately is immediate. Yes, I can tell the difference between 100ms and 1 second or more. It should be push, click. Not push…tick, tock, tick tock, click.
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Yea, why, you jealous you did not turn to Underwriters laboratories?
Grow up…Really man.
I referenced UL in the very first response to this thread. So no, not jealous.
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Read my posts first sentence. ‘UL943 is the spec for GFCI’s.’
Your reply, “Did you just copy and paste that from my post directly above? Sheesh, lol”
Please, Brian. Get real.