As I've said elsewhere on this site, I find no-contact voltage testers to be unreliable. I've seen both false positives and false negatives with mine, especially in the presence of multiple conductors, some of which are hot. The only thing I would use a no-contact voltage tester for is to confirm a condition I already know, and even then I would only use it to test if an entire circuit is live or not, not individual conductors.
If you are getting confusing readings, the first thing I would do is use a proper multimeter to get reliable voltages, then you can go from there.
But to answer your question: no, the GFCI should not be reversing the polarity of the circuit. Are you sure you're wiring up the GFCI correctly? Most (all?) GFCI outlets have different "LINE" and "LOAD" terminals, which are you using?
Residential Kitchen
In a dwelling unit (residential), GFCI protection is only required for kitchen receptacles that serve the countertop surfaces. There's no requirement to GFCI protect receptacles that serve a refrigerator. Unless the fridge is plugged into a countertop receptacle.
National Electrical Code 2014
Chapter 2 Wiring and Protection
Article 210 Branch Circuits
I. General Provisions
210.8 Ground-Fault Circuit-Interrupter Protection for Personnel. Ground-fault circuit-interrupter protection for personnel shall be provided as required in 210.8(A) through (C). The ground-fault circuit-interrupter shall be installed in a readily accessible location.
(A) Dwelling Units. All 125-volt, single-phase, 15- and
20-ampere receptacles installed in the locations specified in
210.8(A)(1) through (10) shall have ground-fault circuit interrupter protection for personnel.
(6) Kitchens— where the receptacles are installed to serve the countertop surfaces.
Garages, Unfinished Basement, and Other Locations
If the refrigerator is in a garage, boathouse, or unfinished basement. All the receptacles are required to be GFCI protected, so the fridge will have to be plugged into a GFCI protected receptacle.
Why does the fridge trip the GFCI?
Any inductive load when switched off, can produce electromagnetic interference (EMI). This interference can, and often does, trip GFCI devices. Most vapor compression refrigerators have a few inductive loads, any of which could cause the trip.
Is there anything that can be done?
There are devices called snubbers that can be used to reduce, or eliminate the effects of EMI. Installing one between the fridge and the GFCI device, could prevent nuisance trips. The best solution though, is to connect the fridge to a non-GFCI protected circuit.
If that's all it takes, why isn't there already one built in?
While most (all) manufacturers are aware that refrigerators can cause nuisance tripping of GFCI devices, most (none) seem willing to provide a solution. It would be complete speculation for me to try and tell you why they don't care, so of course I'll go through a few possibilities.
- Cost.
Plain and simple, it costs money to implement a solution.
- Warranties and Operating Conditions.
Most refrigerators are designed to operate in a kitchen. Running them in dusty, dirty garages and basements could lead to more warranty covered repairs.
Best Answer
The test button on the GFCI should work it doesn’t use the ground. The tester uses the ground with a resistor to create a ground fault since the ground is not there the test function will not work with the plug in tester. As long as the test function on the receptacle works the receptacle is protected as required by code.
The electronics compare both the hot and neutral, a imbalance of more than ~5mA will cause a trip. This is a legal method of GFCI protection with a 2 wire circuit.
IF you want to run a ground wire back to the panel that feeds this circuit OR if there is a grounded circuit in the area that is fed from the same panel recent code changes allow a new separate ground wire to be installed. However if the test button on the GFCI works the receptacle is protected.
Just a note, in my jurisdiction a rental requires a licensed electrician to do anything more than replace a device (light, receptacle or switch) for example. I have heard of some that require a license for even those but have not worked in a state that has that strict requirements. I would verify your local regs so you don’t get in trouble.