GFCI, only built in tester trips

Mike Holt’s blog is a fantastic resource for information. More Inspectors should make it a regular read. The reason for the development was to protect people from electrical shock.

I saw a video a while ago that poked fun, in an educational way, at the GFCI. It went something like this…how many times when a GFCI trips, do you phone around to your friends and say, I’m having a party to celebrate the GFCI that saved my life? Then think how many times you’ve cursed a GFCI because it tripped ad you blamed it for not being able to complete what you were doing?

Knowing of a risk, and then properly classifying it should be part of our care of duty. Exaggerating risks because we don’t understand the principles behind the fundamentals we’ve learned is not.

Any electrical shock is a risk. How many Inspectors get static shocks from homes and then warn their clients that the home is potentially hazardous to them if they have a pacemaker fitted? (Hopefully, the answer comes back ‘nil’)

If you told someone without a pacemaker this, their mind immediately goes to the fact that the house has an electrical fault.

The same thing with this thread.

Sure you can identify the risk that if you come across an ungrounded GFCI, and you test it (against all recommendations) with a 3-light receptacle tested with GFCI button, and it has a metal front, and you are kneeling on damp ground, the 6mA shock you might get for the time you press the button, it might kill you.

But really!!! If you travel to the USA and you choose to go to a bank that is being robbed by armed gunpersons and you choose to ignore their demands to get down on the ground, that might kill you too. I don’t see anyone posting threads about that, and I suspect given the current gun crime in the U.S. (another thread please) the risks would be much higher.

Th real lesson to be learned here is don’t use a night-light (aka a 3-light receptacle tester) which are notoriously inaccurate at identifying defects anyway, to test a GFCI. Use the manufacturers recommended test method. The test button on the receptacle.

This must have been said thousands of times on this and other Inspection threads, but the situation keeps coming up and keeps generating reams of comments about the effects.

Part of being a professional is using the right tool for the job.

A 3-light tester is a quick and dirty method for rapidly identifying some very simple cases where wiring might be incorrect. They are not infallible, they fail to detect many dangerous defects.

Do I use one? Yes

Do I also use other equipment to back up my concerns? Absolutely.

Do I use them for testing GFCI’s? Absolutely not.

and although Mike Holt’s blog is great as a learning tool, sometimes a picture tells a thousand words, so here’s one for you.

https://www.physics.ohio-state.edu/~p616/safety/fatal_current.gif

The original paper from the physics department at OHIO State University can be read here.

Electrical Safety: The Fatal Current

Good stuff. Since the OP in this thread is about an ungrounded GFCI receptacle I felt that the potential danger from plug-in testers was worth mentioning. As you’ve and a few others have stated the go to test method should be the test button on the receptacle or the circuit breaker.

The Ideal 61-501 is a very common Receptacle/GFCI Tester that many HI’s use. Has everyone that uses it read GFCI Testing steps 3 & 4 (especially 3) of the instructions. Comports well with what the GFCI manufacturers say it would seem.

Ideal 61-501 Instructions

Back to the ungrounded GFCI though. Once, many years ago I came across a GFCI that the homeowner has installed on his garage wall about 18" off the concrete floor. I knelt down, steadied myself on the EMT running on the wall to the metal box and GFCI. I pushed the button on my tester and quickly found myself on my butt from the shock. The EMT was not grounded at any point and my cargo short bare knee on the concrete was a great conductor. Agreed, the tester shunt amperage is probably not enough to kill you but it delivered a significant jolt. Had I been on a ladder it would not have been pretty.

The instructions in step 6 could be expanded to include an ungrounded device.

Here is an additional reference for GFCI operation

http://www.inspectcheck.net/client_link_i_had_an_inspection/i_need_electrical_repairs/GFCI%20How%20Do%20They%20Work

Good one Thanks Don

good question and answers. thanks everyone

Thanks everyone for the great info.
So I think the basic MO to follow would be- if one is using the 3 bulb tester-if you come across a receptacle that shows it isn’t grounded, to not use the tester to trip the GFCI. Would you agree?
Thank you

If you want to eliminate the potential shock hazard from an ungrounded installation that’s one way to do it. :smiley:

Sorry for the late response, I used a multi meter.

Not much point since it will not trip the gfi.