20amp QO combo breaker won’t trip with plug tester

R

Roger9

Member
Location
Tampa
Occupation
Electrican
I was at a call today a noticed a circuit outside wouldn’t trip with my plug tester. I was trying to trip the circuit to work on it which wasn’t a big deal cause I have a circuit tracer but I’ve run into this several times and I’m curious if anyone else has. I’ve read online that the only accurate way to test a GFI or GFI/Arc breaker is to push the test button on the breaker?
 
Are you sure the circuit is GFCI protected?

It is not unusual for GFCIs to fail closed so they won't trip.

It is also possible that the ground wire was not run to that receptacle. The test introduces a small current from L to G to trip the GFCI. If the ground is not connected, no current.
 
The plug-in tester relies on the EGC as a place to sink the test current so that there is an imbalance between the two monitored circuit wires.
When a GFCI device is used to allow the continued use of two wire circuits where no EGC was originally installed, the plug-in tester simply cannot be used.

The most common reason for a plug-in tester to not trigger a GFCI device is the absence of an EGC connection.

Individual testers might vary in the amount of current they inject when testing, or may simply have an open test circuit. Have you tried more than one tester?
 
If the circuit is a two wire circuit with out an EGC or missing an EGC your analyzer will not trip it
 
Did you try the tester elsewhere or try another tripping method here?

I use my solenoid tester to trip GFCI circuits away from the GFCI itself.

If there is no EGC, I can use a water faucet or other grounded surface.
 
ptonsparky said:
That's the mfg recommendation, suggestion, etc, but the GFCI should trip with your tester. Did it trip when you pressed the Test button ?
Click to expand...
No egc and the GFCI won’t trip. The tester inserts a resistance from hot to ground, the test button is internal from hot to neutral and will trip with no EGC
 
Correct. The tester doesn't have access to either line ahead of the current sensor ring like the GFCI does.
 
Roger9 said:
I was at a call today a noticed a circuit outside wouldn’t trip with my plug tester. I was trying to trip the circuit to work on it which wasn’t a big deal cause I have a circuit tracer but I’ve run into this several times and I’m curious if anyone else has. I’ve read online that the only accurate way to test a GFI or GFI/Arc breaker is to push the test button on the breaker?
Click to expand...
How long did you hold down the test button? I read somewhere that these testers may take up to 6 seconds to trip the CB.
 
infinity said:
How long did you hold down the test button? I read somewhere that these testers may take up to 6 seconds to trip the CB.
Click to expand...
Egad! 😯 I hope that it doesn't take that long to respond to a shock!

Maybe my testing method is more indicative of real-world operation.
 
For an in-depth look at these analyzers how they can be fooled and their limitations check out Mike Sokol
 
ptonsparky said:
That solenoid tester should pass enough current!!

Have you ever measured the operating current of it?
Click to expand...
No, but it's rated to be approximately 4k ohms; the current obviously varies with the voltage.

About 0.03a at 120v, 0.12a at 480v.
 
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