GFCI trip or not to trip

Alright, can the big shots expain these for me.

  1. Sometimes i have GFCI’s that don’t trip either with the tester or the test button?
  2. Sometimes i have GFCI’s that trip at the trip button but not on my tester?
  3. How do you/can you wire a GFCI with the old two wire BX no ground to protect the outlet when they don’t have the funds to re-wire or they just don’t want to? Are the down stream 2 wire protected or do you need one per?
  4. Anything else i might need to know?

I think i know the answers but i don’t want to confuse anyone and i want to make sure i talk the talk and walk the walk.
I appreciate all the help!


  1. Defective GFCI. Call it out.

  2. Manufacturer’s test is to trip with the button on the GFCI. Your tested may be bad. I trip them with the button and with my tester and write in the report “GFCI receptacles tested by two methods and operated properly”. Marketing.

  3. The ground wire is not reauired for a GFCI to trip. The only process that trips them is a variance between the current on the hot and neutral prongs. If a GFCI is installed with no ground, it will still supply ‘shock protection’, i.e., it will trip if the hoty and neutral vary by more than 1/50th of an amp for more than 1/10th of a second. Check here:

Downstream receptacles with still have GFCI protection if wired to the load side of the GFCI.

  1. Read the article, and other offerings on the net.

Hope this helps;

I carry 3 testers. If i question something, i try the other. That is why i am asking that question. So if someone else has an answer to that, that would be great!
As always, i apprecaite you help Will. I ahve read many things from your links and they are awesome!

An ungrounded GFCI will not trip with your plug in tester because it uses the grounding wire to create the imbalance. No grounding wire, no imbalance. It will however trip with a Wiggy between the hot and a grounded surface. Like Will said, the test buttons are an acceptable test according to UL and the mfgs.

If they dont trip…they can be malfunctioning…, incorrectly wired on some older models that still show voltage but don’t trip…

Either way…Note they don’t test correctly, note to contact a licensed electrical contractor and always recommend GFCI’s on older 2 wire systems to protect against electrocution in all areas we would require them today…

Small price to pay for safety…:slight_smile:

the new GFCI’s (in OCT.) will not work on the 2 wire system.

More info?


I think someone is pulling your leg
This is the new standard

The new UL and CSA requirements include:
End of Life Provision: when a GFCI receptacle is incapable of passing its internal test function (it can no longer provide ground fault protection) it will either a) render itself incapable of delivering power, or b) indicate by visual or audible means that the device must be replaced.
Reverse Line-Load Miswire: a GFCI will deny power to the receptacle face if it is miswired.
In the United States, manufacturers must stop producing old versions of GFCIs on July 28, 2006, and must introduce new, redesigned GFCIs after that date. Distributors can sell and contractors can install old GFCIs until their supplies run out. The UL revisions will not affect the NEC, which regulates installations, not products.

lol…I am in the present Mike…lol…speaking to HI’s will without a doubt run into more older GFCI’s than Newer GFCI’s…:slight_smile:

But I got ya brother…I undestand…:slight_smile:

Thanks, Greg. :wink:

Excellent Greg…Great To Know…Guess everything is speculation until which time it is NOT speculation…:slight_smile:

I have heard the rumor about the required ground on a GFCI too but I can’t find any real reference to it in the literature. Where is Snopes when you need it?