testing gfci's

[LarryFine]

Now that statement brings out my skeptical nature. As I understand it, the test button shunts a small current to the line side grounded conductor, while a plug in tester shunts roughly the same small current to the equipment grounding conductor. The imbalance seen by the sensing coil should be roughly the same by either method. I can't see how a plug in tester could cause premature failing of the device any more than use of the test button. :roll:

Same here, plus down-stream receptacles fed from GFCI load-side terminals can only be tested with a plug-in tester (or a wiggie or other 'artificial' hot-to-ground load.)

 

[Mike03a3]

Same here, plus down-stream receptacles fed from GFCI load-side terminals can only be tested with a plug-in tester (or a wiggie or other 'artificial' hot-to-ground load.)

I believe the recommended way to test the load side receptacles is to plug in a lamp, push the GFCI test button and see if the light goes out.

Having typed that, I have to admit I generally use a plug-in tester or an Ideal Sure-Test. I'd be interested in the official logic behind the claim that a plug-in shortens the life of a GFCI more than the test button.

 

[don_resqcapt19]

I had a long phone conversation with a tech guy from one of the major GFCI manufacturers last year. He said that you can't call the button a test of the GFCI, but only of the mechanics of the GFCI. His postion was because the resistor is sized to flow 8 to 12 mA of current it doesn't really test the 4-6 mA trip point.
Don

 

[Mike03a3]

I had a long phone conversation with a tech guy from one of the major GFCI manufacturers last year. He said that you can't call the button a test of the GFCI, but only of the mechanics of the GFCI. His postion was because the resistor is sized to flow 8 to 12 mA of current it doesn't really test the 4-6 mA trip point.
Don

So, what does he consider an appropriate test?

The resistor is probably sized that way because you might have to hold the test button in for more than 6 seconds if it was sized correctly. The UL curve of current vs trip time allows a lot of time at 6ma.

 

[LarryFine]

I believe the recommended way to test the load side receptacles is to plug in a lamp, push the GFCI test button and see if the light goes out.

Of course, the light will go off if the GFCI trips, but that doesn't tell us whether a downstream 5ma fault will trip the device.

E = I X R, so R = E/I

120 = 0.005 x R, so R = 120/0.005

A 24K resistor should just trip a GFCI. If I wanted to make my own tester, I'd probably use a 12K resistor to produce 10ma.

 

[al hildenbrand]

What about the neutral / "ground" short?

What about the neutral / "ground" short?

Don't forget, part of a GFCI includes the line to neutral winding that creates an unbalance current only if the downstream neutral looses integrity and completes a circuit back to the main bonding jumper.

I'm not aware of any tester, internal or external, that verifies that this little circuit is still intact and operational.

I'm talking about the right hand toroid primary winding (in red) in the graphic below.

 

[don_resqcapt19]

Mike,

So, what does he consider an appropriate test?
The resistor is probably sized that way because you might have to hold the test button in for more than 6 seconds if it was sized correctly.

He didn't specify a test. As far as the sizing of the resistor, he said that it was to make sure that the relay worked and nothing else.
Don

 

[tom baker]

All: Why fuss with making jigs and jumping the GFCI to test it?
The best, easiest and only way (110.3(B) is to use the test button. Jumping to ground may not work if there is no ground. And you are taking a risk, old GFCIs fail in the energized condition.