Commercial refrigerator malfunctioning on gfi.

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Just had a customer call and say their commercial refrigerator was malfunctioning, shutting off, circuit board resetting. He called the manufacturer, and they asked if it was on a gfi circuit, which it is. They said he needed some sort of filter, because their product doesn’t like gfi’s.
I wonder if the refrigerator has some internal ground fault detection circuitry of its own that is falsely tripping due to an interaction with the grounded neutral detection circuit in the GFCI breaker or receptacle (which Jon mentioned in his post #9 above). It seems hard to believe that a small test signal of several kHz at the line input of the refrigerator would directly cause internal digital logic in its controller to malfunction. But such a test signal intentionally has common-mode content, which ground fault detection circuitry is designed to pick up with a high level of sensitivity. A filter which attenuates such signals (as it seems the manufacturer is suggesting) might prevent this from happening.
 

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
The owner said they recommended a Tripplite isobar surge protector, which he wrote down the model back at the plant, but doesn’t have it with him. We are spending the weekend down at his coastal property right now.
Can’t get away from work, his nephew’s camper cord wasn’t long enough to reach the pedestal, (I had dibs on connecting closer) so I had to run another outlet.
 

garbo

Senior Member
Just had a customer call and say their commercial refrigerator was malfunctioning, shutting off, circuit board resetting. He called the manufacturer, and they asked if it was on a gfi circuit, which it is. They said he needed some sort of filter, because their product doesn’t like gfi’s. Doesn’t trip the outlet, just screws up the electronics in the refrigerator. Just a heads up if anybody else has came across this problem. Manufacture said the problems started when the code requirements changed.
The large hospital that I retired from had several freezers and an expensive doubled sided refrigerated case with 4 full size doors on both sides ( one side was clean room where they mixed medicines ). They would trip out 5 ma trip GFCI bolt on 20 amps on single pole circuit breakers once every 5 to 7 days. I spent time on fancy 8 door unit. Removed wires and meggered everything but the control board with a megger first using 250 volts then 500 volts and all readings were good. Finally replaced GFCI 5 ma trip circuit breakers with think they were called equipment GFCI circuit breakers and none of them ever tripped out. Would clear it with the local AHU before changing over to 30 ma trip breakers.
 

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
The large hospital that I retired from had several freezers and an expensive doubled sided refrigerated case with 4 full size doors on both sides ( one side was clean room where they mixed medicines ). They would trip out 5 ma trip GFCI bolt on 20 amps on single pole circuit breakers once every 5 to 7 days. I spent time on fancy 8 door unit. Removed wires and meggered everything but the control board with a megger first using 250 volts then 500 volts and all readings were good. Finally replaced GFCI 5 ma trip circuit breakers with think they were called equipment GFCI circuit breakers and none of them ever tripped out. Would clear it with the local AHU before changing over to 30 ma trip breakers.
What’s weird is, it is not tripping the gfi, the refrigerator circuit board is resetting, and the manufacturer says it’s the gfi causing it, and to remove it. Haven’t got back out there yet, I think the owners son has already changed out the receptacle. I’m on a far more important project for him right now finishing up a new 1600 amp service for him.
 
Top