When I plug my freezer to an outlet not gfi protected it works fine, but when I plug it into an outlet that is gfi protected it pops the breaker. I dont understand why.
All fridge and freezers should be plugged into an NON-GFCI protected outlet, since the inital start of the compressor can cause the GFCI to detect a millivolt surge, when the compressor starts, causing the GFCI to trip.
If this is in a kitchen, you should change out the outlet to a non-GFCI outlet BUT only to a single outlet that only has the freezer plugged into.
If it's in a basement, garage, or some other place with a GFCI outlet, you can change out that one outlet to a standard single outlet device of which ONLY the freezer will be plugged into and remain code compliant. You will need to make sure that any other outlets served by that current GFCI outlet stay protected, by installing the GFCI you swap out, and put it in place of the NEXT outlet in the circuit.
By doing that, you will have the first outlet that was the GFCI, now a single outlet NON-GFCI serving the freezer, but the next outlet in the branch circuit gets a GFCI outlet, thus protecting the rest of the circuit, in compliance with the NEC (National Electric Code)
If you need further help with this, please comment back and I'll check back later and provide you more detailed info. Of course, be sure to turn off the breaker to this circuit before making any changes to the outlets, etc.
Hope you find this Very Helpful and best regards!