GFI on commercial refrigerators

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cpickett said:
If the mfr is sure it won't work with a GFCI (high leakage current), then that sure doesn't make me want to buy the thing! Especially a washing machine for an area that will have water splashed all around.

Unlike AFCIs, GFCIs work every time and when they trip, it's usually for a good reason! I don't like getting shocked...
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It is impossible to reduce leakage current on large appliances to the point a GFCI will never trip... Its not the manufacturer's fault physics is beyond their control.
 
roger said:
Sounds like you don't like the answers you have received. You can try to get around the code but be prepared to take all the liability that goes with it. It would behoove you to read the ROP's that brought the rule into the code.

Roger
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Can you link/copy the ROPs?
 
TomYing said:
Thanks everyone for your input and opinions. I come from a commercial equipment manufacturing background and the number one reason commercial refrigeration manufacturers don't like GFI's, other than the fact that they are not always reliable. Is that in a commercial refrigeration setting, literally thousand of dollars of food could be spoiled and lost over night, commercial ranges tripping can possibly provide undercooked food, neither an acceptable scenario. Commercial appliances are in the business of providing 'safe food'. Kitchens are eclectically and electronically noisy.

NEC made rulings by saying protect everything without drilling down to the causal and impact of the rule. So I guess there is no real answer other than to try to follow the commercial manufacturers installation recommendations and try to discuss and reason with the local safety inspectors for approval or solution,
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Let me start off by saying I am 100% on your side, and 100% on the side of commercial appliance manufacturers.

It is 100% impossible to rid an appliance of capacitance to ground. Any power system will have spikes and sharp rising edges switching and breaking through reactance.

The two combined will trip GFCIs. There is no way around it.

Manufacturers can isolate internal components from ground, they could even add isolation transformers to each fridge reducing the number of trips.

In the end you still have what in total amounts to hundreds of feet of conductor capacitively coupled with the frame and chassis or the iron core of a transformer.

Physics can not be bypassed.

Ultimately what this all boils down to a litigatory reaction to an epic failure in understanding the physics (ohms law) protecting life and property at no fault of the electrician, manufacturer or general user. It is now making itself known that even a litigation reflex isn't a solution.

Just expressing my educated opinion :)
 
TomYing said:
Thanks everyone for your input and opinions. I come from a commercial equipment manufacturing background and the number one reason commercial refrigeration manufacturers don't like GFI's, other than the fact that they are not always reliable. Is that in a commercial refrigeration setting, literally thousand of dollars of food could be spoiled and lost over night, commercial ranges tripping can possibly provide undercooked food, neither an acceptable scenario. Commercial appliances are in the business of providing 'safe food'. Kitchens are eclectically and electronically noisy.

NEC made rulings by saying protect everything without drilling down to the causal and impact of the rule. So I guess there is no real answer other than to try to follow the commercial manufacturers installation recommendations and try to discuss and reason with the local safety inspectors for approval or solution,
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You can get around the GFCI requirement by not using cord and plug connections (for now). I do believe 2020 however does require GFCI for all dishwashers - IMO shouldn't apply to hard wired, but guessing they will be adding more things in years to come with not the greatest justification like the have with most GFCI requirements changes since at least 2005.
 
mbrooke said:
Can you link/copy the ROPs?
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NFPA's site. You will have to search for yourself but there were a few regarding electrocutions in commercial kitchens and I believe refrigerators were involved.

I would guess there are thousands of refrigerators in commercial kitchens working fine on GFCI's since the rule change came into play.

Roger
 
roger said:
NFPA's site. You will have to search for yourself but there were a few regarding electrocutions in commercial kitchens and I believe refrigerators were involved.

I would guess there are thousands of refrigerators in commercial kitchens working fine on GFCI's since the rule change came into play.

Roger
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Thanks :) Do you know the specific code cycle they were mandated?

Personally, the code should allow for other approved means. Mandating GFCIs without options is against the structure and intent of the code IMO.



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I like the concept of a monitored EGC. I've suggested in the past that higher leakage be permitted when it is known that the EGC is intact.

Jon
 
mbrooke said:
Thanks :) Do you know the specific code cycle they were mandated?

Personally, the code should allow for other approved means. Mandating GFCIs without options is against the structure and intent of the code IMO.



View attachment 2556697
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It does allow for other means - so far. Direct wired appliances do not need GFCI, does create more problems if you want to move or frequently interchange for maintenance, cleaning etc.
 
mbrooke said:
What if I want plug in?
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Then buy a unit that works with a GFCI. Over the last 19 years that the requirement has been in the code there are hundreds of thousands (probably more) of refrigerators working fine in commercial kitchens, there is no reason to cater to an inferior product that can not comply.

Roger
 
roger said:
Then buy a unit that works with a GFCI. Over the last 19 years that the requirement has been in the code there are hundreds of thousands (probably more) of refrigerators working fine in commercial kitchens, there is no reason to cater to an inferior product that can not comply.

Roger
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There is not a single unit that will not eventually trip a GFCI. Unless you know how to bypass physics.
 
mbrooke said:
There is not a single unit that will not eventually trip a GFCI. Unless you know how to bypass physics.
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I didn't say there was and to go another step further, there's not a single unit that will not eventually wear out. When either happens it's time for repairs or replacement.

Roger
 
mbrooke said:
Xc=1/2pifc exists on units of all ages, including brand new units.
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And in normal instances it progressively gets worse to a point beyond safe limits. Have you ever been involved with Isolated Power Systems in OR theaters? If not take time to look at how they are designed and installed to minimize and monitor leakage problems.

It's kind of funny to see you post many "the sky's falling" type threads about code deficiency and here you want to do away with a rule that came about due to electrocutions in work places.

Roger
 
roger said:
And in normal instances it progressively gets worse to a point beyond safe limits. Have you ever been involved with Isolated Power Systems in OR theaters? If not take time to look at how they are designed and installed to minimize and monitor leakage problems.

It's kind of funny to see you post many "the sky's falling" type threads about code deficiency and here you want to do away with a rule that came about due to electrocutions in work places.

Roger
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I encourage you to look into capacitors and why they work in harmonic filtering.

Resistive leakage tends to get worse with age, for all practical purposes Xc=1/2pifc remains the same. This is why tan delta testing works are a reliable indicator.

I'm glad you brought up OR supplies. In addition to using Hypalon or XLPE insulation to limit resistive leakage, run length of isolated ground circuits is kept as short as possible to limit shunt capacitance since it is impossible to eliminate with any type of insulation.

Which takes us to refrigerators. The internal wiring of all refrigerators will always have shunt capacitance to ground, no matter its insulation or routing.

At 60Hz steady state 0.01 uF gives 0.045 milliamps of leakage current. With a sharp or rising edge in the sinewave, 50 milliamps will momentarily pass to ground.

Here is, calculator. The the ohm value decreases as frequency increases:


http://www.sengpielaudio.com/calculator-RC.htm
 
mbrooke said:
I encourage you to look into capacitors and why they work in harmonic filtering.

Resistive leakage tends to get worse with age, for all practical purposes Xc=1/2pifc remains the same. This is why tan delta testing works are a reliable indicator.

I'm glad you brought up OR supplies. In addition to using Hypalon or XLPE insulation to limit resistive leakage, run length of isolated ground circuits is kept as short as possible to limit shunt capacitance since it is impossible to eliminate with any type of insulation.

Which takes us to refrigerators. The internal wiring of all refrigerators will always have shunt capacitance to ground, no matter its insulation or routing.

At 60Hz steady state 0.01 uF gives 0.045 milliamps of leakage current. With a sharp or rising edge in the sinewave, 50 milliamps will momentarily pass to ground.

Here is, calculator. The the ohm value decreases as frequency increases:


http://www.sengpielaudio.com/calculator-RC.htm
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You're missing the point, we all know there is capacitive reactance and leakage in equipment and conductors, it's a given fact, designing equipment to keep it within GFCI limits is all they need to do. You should probably send the calculator link to the refrigerator manufacturer of your choice. As I said before, there are refrigerators in commercial kitchens that are still working on GFCI's that we installed upwards of 20 years ago so you're not going to get anywhere with the argument that they can't be made to do so.

If you think you can put together a convincing argument to change the rule spend some time putting one together for a PI but don't hold your breath thinking you can get it accepted.

Roger
 
roger said:
You're missing the point, we all know there is capacitive reactance and leakage in equipment and conductors, it's a given fact, designing equipment to keep it within GFCI limits is all they need to do. You should probably send the calculator link to the refrigerator manufacturer of your choice. As I said before, there are refrigerators in commercial kitchens that are still working on GFCI's that we installed upwards of 20 years ago so you're not going to get anywhere with the argument that they can't be made to do so.

If you think you can put together a convincing argument to change the rule spend some time putting one together for a PI but don't hold your breath thinking you can get it accepted.

Roger
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I know, however it is not physically possible to design reactive leakage current within limits. Steady state yes, transient no.

Lightning strike, POCO switching, fault on another circuit... those fridges of 20 years will trip.
 
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