GFCI trip random times and locations

[BMacky]

Having a little trouble with some GFCIs I installed a while ago. Here's the scenario:

A year and a half ago, I upgraded a 100A service to 200A, along with the grounding upgrades per NEC. Added some convenience outlets in the customer's garage: 2 off a sub panel in the proximity, and one right near the new main, still in the garage. Everything metal is grounded back to each panel, exposed wiring is all MC cable.

Customer has an alarm system, Internet router, battery charger for cordless tool, and a tankless water heater connected in the garage, between the two circuits that are powering three separate devices. Tankless water heater has a zone control relay that converts line to 24VAC for thermostat inside the house.

Internet connection was down a while back and they went to the garage and found the GFCI tripped where the router was plugged in. I stopped by and ran the router cord/plug over to another GFCI (these two are on the same circuit but are not line/load wired) just to see if the fault followed the load. It worked for a while (week or so) but tripped again. As well as the original GFCI which also had a cordless phone base connected to it. Later, the third GFCI where the cordless tool battery charger was plugged in tripped. It's on a separate circuit and different panel.

I checked the grounding, connections in panels, etc. Cannot seem to come up with a common denominator to this. The GFCIS are not name brands, and they are all tripping regardless of what is plugged in. Beginning to wonder if they are sub-par products. I realize they are designed to trip on legit faults but these were doing fine for a year and then all started acting strange just recently, and only in the garage setting. Other household GFCIs are not affected, and are Leviton.

What I am wondering before I replace all three is if anyone out there has ever had some sort of transient GFCI tripping where there were several GFCIs in a residence that all seemed to be affected, yet on different circuits and not downline loaded?

Thanks in advance for any tips or feedback.

Bob

 

[Smart $]

My thought while reading you post was bad bunch of GFCI's...

The I got toward the end and see you are thinking the same but questioning your instincts. Go with your gut... :happyyes:

 

[PetrosA]

I recommend using name brand GFIs from a supply house which will usually take them back within the warranty period and replace them for free. I use mostly PNS and Hubbell. I worked for a guy who was buying the $7 GFCIs from some outfit in Florida. They had a pretty high failure rate. I once had to drive 1 hour each way to a customer to replace one of these units two weeks after it was installed. So this guy was paying me 2.5 hours to make a warranty repair which eats up an awful lot of savings on cheap GFCIs. In the last three years I've had one call back on a PNS GFCI receptacle and one on a Hubbell TRWR GFCI - probably a 1 in 400 failure rate. If you do the math it might look like this for a 1 in 10 failure rate:

10x$7=$70 for cheap GFCIs
10x$13=$130 for name brand
Difference=$60
One and half hours lost time per failure at your billable rate (in my case $65/hr)=$97.50
I just lost $37.50 over the $60 difference on a warranty repair, and I know it will happen again if I'm using the cheapies, plus if you're ordering from out of state you either can return them and pay shipping or just pay for the replacement yourself which increases your losses even more.