I would like to hear if anyone else is having some of the same problems that I am. My company does build outs of restaurants each year. Every time that we finish one of these it seems like I receive phone calls about the GFI's tripping and not being able to reset in the kitchen. Even if I replace the GFI with a new device, that new device will trip also. This happens on all different kinds of equipment so there is no pattern on which unit is causing the GFI's to trip. They range from the safe to the deep fryer. I am not using cheap devices and the circuitry is installed professionally. Some of the circuits are dedicated with a dedicated neutral and ground. Just curious to see if anyone else is having this same issue?
GFI's in commercial kitchens
- Thread starter cdb277
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kwired
Electron manager
- Location
- NE Nebraska
The device is doing exactly what it is intended to do, protecting the user from a ground fault within the equipment plugged into it. Stop treating the symptoms and treat the actual problem.
(I don't mean to sound sarcastic but it is what it is.)
The problem is the manufacturers haven't done their job in building a piece of equipment that will work with code compliant wiring. We always hear "the manufacturer says the GFCI is not needed" and of course we have to tell them they're wrong.
Roger
Roger
PetrosA
Senior Member
- Location
- Lancaster, Pennsylvania
I suspect it's a problem with the appliance equipment as well. If you've ever taken any commercial equipment apart, you know that all kinds of grease, dirt, soap scum and other crap gets built up inside from cleaning or from lack of cleaning. Some things aren't used as designed, and can't keep out the contaminants they're subjected to (like warming shelves in Auntie Anne stores used as butter melters 
GROSS!). Some switches, indicator lights and other controls aren't very well sealed and grease or wash liquid can get in there and coat things from frame to contacts which is enough to trip a GFI. Manufacturers need to do better with sealing and/or potting controls in the units.
GROSS!). Some switches, indicator lights and other controls aren't very well sealed and grease or wash liquid can get in there and coat things from frame to contacts which is enough to trip a GFI. Manufacturers need to do better with sealing and/or potting controls in the units.fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
I got a complaint that the GFCI outlet was bad that fed an ice-maker. I plugged it into a regular outlet through a test cord that had all three conductors exposed. The exposed wires were each wound into a ten-turn coil. With the hot and neutral coils in a clamp-on meter's jaws I read 0.3 amps, indicating an unbalanced current of 0.030amps.
I cut the plug off the ice-maker, red tagged it, and told them to buy a new one.
I cut the plug off the ice-maker, red tagged it, and told them to buy a new one.
cadpoint
Senior Member
- Location
- Durham, NC
It's a kitchen, and then there is equipment!
I agree with the others!
I agree with the others!
squaredan
Senior Member
- Location
- Pennsylvania
kwired
Electron manager
- Location
- NE Nebraska
If you pass the conductor you are measuring through your CT ten times you will get a measurement of 10 times the actual current. Easy way of getting a more accurate measurement of low values.
He also measured both the supply and return conductor of a circuit at same time. Since they will cancel each other any reading you get is equal to amount of current that is flowing outside the intended path. This is exactly what the GFCI uses to sense ground faults, both conductors pass through a CT inside the device, if current coming in is equal to current going out there is no voltage developed in the CT, if there is a ground fault some current is not going to be returning on either of the conductors passing through the CT - then you will develop some voltage in the CT and it will activate the trip mechanism if the current level reaches the designed trip level.
Most meter manufacturers have accessories to assist you in doing such measurements.
Here is one by amprobe.
http://www.amprobe.com/Amprobe/usen/Accessories/Other/ELS2A.htm?PID=73229
Here is one by amprobe.
http://www.amprobe.com/Amprobe/usen/Accessories/Other/ELS2A.htm?PID=73229
I wouldn't recommend that method. What happens if you get 10 turns with one wire, and 9.9 with the other? I think you would get a much more accurate measurement just isolating the ground wire and directly measuring the current through it.
As Augie mentioned, you can get test equipment made to measure ground fault current.
kwired
Electron manager
- Location
- NE Nebraska
How are you only going to pass 9.9 turns through your meter?
Just because you don't measure any current on the equipment grounding conductor doesn't mean there isn't any current returning through some other path. This is exactly why GFCI's are permitted for replacing two wire receptacles even though there is no equipment ground present at the receptacle. More than 4-6 mA flows outside the intended circuit path - it trips.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Thank you KWired.
Thank you KWired.
Your explanations were better than I would have done.
I measured for difference current in hot/neutral because I didn't know where the leakage current was going, it could have been through the grounding wire, the copper pipe connected to the ice maker or into the concrete the ice maker sat on. Actually I didn't care, all I wanted to know was if the leakage was above the trip current of a GFCI.
The Amprobe adapter referenced by augie47 is a newer version of the one I have from 1970's. It does not serve the purpose of measuring the difference current in the hot/neutral as explained above, it just measures the current in the hot conductor.
I have a kit I use for puzzling measurement problems. It has a variety of digital and analog meters. It also has a set of adapters I make out of IEC extension cords. (The connectors are those you see in old computer power supply cords and power supplies.) I bought a half dozen from Cyberguys.com. It consists of the following:
1. NEMA 15A 120V 3 prong plug to female IEC
2. NEMA 15A 240V 3 prong plug to female IEC
3. three alligator clips to female IEC
4. NEMA 20A 120V 3 prong outlet to male IEC
5. NEMA 20A 240V 3 prong outlet to male IEC
6. three alligator clips to male IEC
7. Female IEC cord -- with each conductor exposed and wound into a 10-turn coil -- to male IEC
also
8. edison base male to 15A 120V 2 prong outlet
9. edison base female to 15A 120V 2 prong plug
10. 15A 120V 2 prong plug to 3 prong 15A 120V outlet.
With these items I can cobble together almost any corded circuit I need for measurements.
Thank you KWired.
Your explanations were better than I would have done.
I measured for difference current in hot/neutral because I didn't know where the leakage current was going, it could have been through the grounding wire, the copper pipe connected to the ice maker or into the concrete the ice maker sat on. Actually I didn't care, all I wanted to know was if the leakage was above the trip current of a GFCI.
The Amprobe adapter referenced by augie47 is a newer version of the one I have from 1970's. It does not serve the purpose of measuring the difference current in the hot/neutral as explained above, it just measures the current in the hot conductor.
I have a kit I use for puzzling measurement problems. It has a variety of digital and analog meters. It also has a set of adapters I make out of IEC extension cords. (The connectors are those you see in old computer power supply cords and power supplies.) I bought a half dozen from Cyberguys.com. It consists of the following:
1. NEMA 15A 120V 3 prong plug to female IEC
2. NEMA 15A 240V 3 prong plug to female IEC
3. three alligator clips to female IEC
4. NEMA 20A 120V 3 prong outlet to male IEC
5. NEMA 20A 240V 3 prong outlet to male IEC
6. three alligator clips to male IEC
7. Female IEC cord -- with each conductor exposed and wound into a 10-turn coil -- to male IEC
also
8. edison base male to 15A 120V 2 prong outlet
9. edison base female to 15A 120V 2 prong plug
10. 15A 120V 2 prong plug to 3 prong 15A 120V outlet.
With these items I can cobble together almost any corded circuit I need for measurements.
kwired
Electron manager
- Location
- NE Nebraska
I just have 2 test cords, one with 15 amp 125 volt male end and one with female end and both with alligator clips on opposite end. There are many things you can cobble together with those for testing something - if they need to be longer for some reason just plug an extension cord into them.
I'm just saying there are better ways - especially before cutting the cord off someone's appliance. Just because there is a 30 mA ground fault doesn't mean the appliance is trash.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
School classroom commercial kitchen
School classroom commercial kitchen
This was in a school. The machine was older than dirt. The "repairman" had already moved the cord to an unprotected receptacle.
I always erred on the side of safety in schools. Every now and then I would have to lead a school administrator through a "guided meditation" of how his idea of "safe enough" would sound on the witness stand.
If they didn't like it, they could fire me. Being an electrician in the schools was basically a hobby -- I didn't NEED the job so I could impose my ideas of safety more easily than those who needed their jobs.
School classroom commercial kitchen
This was in a school. The machine was older than dirt. The "repairman" had already moved the cord to an unprotected receptacle.
I always erred on the side of safety in schools. Every now and then I would have to lead a school administrator through a "guided meditation" of how his idea of "safe enough" would sound on the witness stand.
If they didn't like it, they could fire me. Being an electrician in the schools was basically a hobby -- I didn't NEED the job so I could impose my ideas of safety more easily than those who needed their jobs.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Huh?
Huh?
ul_GroundFaultProtectiveDevices.pdf
"It states that a Class A GFCI trips when the current to ground has a value in the range of 4 milliamps to 6 milliamps, and references UL 943, the Standard for Safety for Ground-Fault Circuit-Interrupters." White Book KCXS
"GFPE (Ground-Fault Protection of Equipment) This type of device is designed typically to trip in the 30 mA or higher range, and therefore is not used for personnel protection." White Book KDAX
Huh?
ul_GroundFaultProtectiveDevices.pdf
"It states that a Class A GFCI trips when the current to ground has a value in the range of 4 milliamps to 6 milliamps, and references UL 943, the Standard for Safety for Ground-Fault Circuit-Interrupters." White Book KCXS
"GFPE (Ground-Fault Protection of Equipment) This type of device is designed typically to trip in the 30 mA or higher range, and therefore is not used for personnel protection." White Book KDAX
So why did you cut the plug off of the machine? You stated you read 30 mA. GFCI's in commercial kitchens are for personnel protection and must be class A devices.
Roger
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fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Roger, please read post #16 as to why I cut the cord.
And please read the text you quoted Class A GFCI trips 4-6milliAmps.
In a school I could care less about protecting the equipment, it's the personnel and the students I care about.
And please read the text you quoted Class A GFCI trips 4-6milliAmps.
In a school I could care less about protecting the equipment, it's the personnel and the students I care about.
Exactly, a class A device has to trip at a much lower current than a class B device. With that said, even though you did this at a school that has nothing to do with the NEC requirement and this is the "NEC" forum we are discussing this in.
Roger
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