GFCI's and Circuit tester

[TVH]

I recentely used my hand held GFCI Tester on a GFCI protected ciruit. The tester showed satisfactory wiring but the circuit did not trip when the GFCI button was pressed on my tester. Back at the panel I pushed the test button located on the circuit breaker and it tripped.

Can someone tell me what is going on? Is the test button on the GFCI breaker a mechanical trip only or is an actual fault current created when the GFCI Breaker is pushed? Appreciate your response.
TVH

 

[GoldDigger]

I recentely used my hand held GFCI Tester on a GFCI protected ciruit. The tester showed satisfactory wiring but the circuit did not trip when the GFCI button was pressed on my tester. Back at the panel I pushed the test button located on the circuit breaker and it tripped.

Can someone tell me what is going on? Is the test button on the GFCI breaker a mechanical trip only or is an actual fault current created when the GFCI Breaker is pushed? Appreciate your response.
TVH

Simple enough, and the subject of several other threads here.
The built in test button uses a resistor to take a controller amount of current from the hot wire on the load side of the receptacle and feed it around the sensing transformer back to the neutral (or take a controller amount of current from the not on the line side of the transformer and feed it into the neutral on the load side.
Since it has access to both sides of the sensing coil (transformer) it can do this.
An external tester only has access to the load side of the sensor, so to create a current imbalance it has to send some current through the actual ground wire.
If there is no ground at the outlet, the plug-in tester cannot work.

The NEC allows the use of a three wire GFCI receptacle as a replacement for a two-wire receptacle with no ground feed to the box if a label is attached saying that there is no ground.

If the receptacle had a false ground, created by attaching its ground terminal to the neutral, the plug-in tester would not be able to detect that and the GFCI test button would just be sending current back down the neutral, which would not trip the breaker.

 

[hurk27]

I recentely used my hand held GFCI Tester on a GFCI protected ciruit. The tester showed satisfactory wiring but the circuit did not trip when the GFCI button was pressed on my tester. Back at the panel I pushed the test button located on the circuit breaker and it tripped.

Can someone tell me what is going on? Is the test button on the GFCI breaker a mechanical trip only or is an actual fault current created when the GFCI Breaker is pushed? Appreciate your response.
TVH

It sounds like you have either a high impedance grounding path back to the panel or none at all, the three light testers can show a receptacle to be wired correctly even if there is a very high impedance path for a ground fault, capacitive coupling can also light the second neon light even when there is no EGC, while the GFCI does not require a ground to function and is allowed to protect a non-grounded circuit if the circuit is expected to have a ground you might want to test this path by using a loaded meter like a wiggy or an Ideal Volt con solenoid type voltage tester.

The three light tester using a 15k ohm resistor from the load side hot to ground to test the circuit, the button on the GFCI breaker or receptacle type uses a 15k ohm resistor from the load side hot to the line side neutral through the test button, this is why the test button on the device is the only UL listed method for testing a GFCI.

Also note that if you push the test button on a three light tester and one of the lights goes out that is a good indication that you don't have a true ground, but not always as it is only applying a 15k ohm load that if there is enough capacitive coupling or inductive voltage even this can cause a false reading of the circuit.

Gold digger is a faster typer them me LOL

 

[hurk27]

I didn't think of the bootleg ground off the neutral and gold digger is very correct, connecting the ground to the receptacle is a vary dangerous thing to do and not only not allowed by the NEC if someone were to get hurt from this it could be a liability issue, It would be a good idea to check if this was done.

If this was done at a receptacle type GFCI and was done from th eline side neutral the three light tester would trip the receptacle GFCI, but still not good to do.