Supermarket Display Case ... Appliance? Disconnect?

[mdwyer]

Historically, refrigerated display cases in a grocery store (e.g, reach-in frozen food) have power (lights, defrost, fans, controls) from multiple panels, often different voltages (e.g, some 120, some 208). Not sure if it is usually considered an appliance or not (um, industrial?), given the vague definition of appliance, but if it is an appliance, then looking at 2011 sec 422.30, I see

422.30 General. A means shall be provided to simultaneously disconnect each appliance from all ungrounded conductors in accordance with the following sections of Part III. If an appliance is supplied by more than one branch-circuit or feeder, these disconnecting means shall be grouped and identified as the appliance disconnect.

That seems pretty hard to meet. Any EC's doing grocery store work running into problems with this section in the field?

From section 100: Appliance. Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, and so forth.

 

[iwire]

Yes I work for a company that is always doing supermarkets.

No we have not run into any problems with disconnects but I have thought about it as well.

 

[Gregg Harris]

Historically, refrigerated display cases in a grocery store (e.g, reach-in frozen food) have power (lights, defrost, fans, controls) from multiple panels, often different voltages (e.g, some 120, some 208). Not sure if it is usually considered an appliance or not (um, industrial?), given the vague definition of appliance, but if it is an appliance, then looking at 2011 sec 422.30, I see

422.30 General. A means shall be provided to simultaneously disconnect each appliance from all ungrounded conductors in accordance with the following sections of Part III. If an appliance is supplied by more than one branch-circuit or feeder, these disconnecting means shall be grouped and identified as the appliance disconnect.

That seems pretty hard to meet. Any EC's doing grocery store work running into problems with this section in the field?

From section 100: Appliance.Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, and so forth.

Would you not be applying article 440 for your application?

 

[iwire]

Would you not be applying article 440 for your application?

440 may or may not apply

440.3 Other Articles.

(B) Articles 422, 424, or 430. The rules of Articles 422,
424, or 430, as applicable, shall apply to air-conditioning and
refrigerating equipment that does not incorporate a hermetic
refrigerant motor-compressor. This equipment includes devices
that employ refrigeration compressors driven by conventional
motors, furnaces with air-conditioning evaporator coils
installed, fan-coil units, remote forced air-cooled condensers,
remote commercial refrigerators, and so forth.

 

[kwired]

Would you not be applying article 440 for your application?

Iwire quoted the applicable section.

Basically if the compressor is remote from the unit in question, then 440 doesn't apply.

 

[charlie b]

If a disconnect is even required for this type equipment, then 422.31(B) would allow the breaker to serve as the disconnect (if it is lockable).

 

[K8MHZ]

If a disconnect is even required for this type equipment, then 422.31(B) would allow the breaker to serve as the disconnect (if it is lockable).

I think the question was also about the grouping of the disconnects, be they breakers or not.

For instance, if the lights are fed from a 120 volt panel and the glass defrosters are fed from a 277 panel, how do you group them together?

 

[GoldDigger]

I think the question was also about the grouping of the disconnects, be they breakers or not.

For instance, if the lights are fed from a 120 volt panel and the glass defrosters are fed from a 277 panel, how do you group them together?

It does sound as if you need to provide additional disconnects beyond just the ones in the panels in order to allow the needed grouping.

 

[kwired]

I think the question was also about the grouping of the disconnects, be they breakers or not.

For instance, if the lights are fed from a 120 volt panel and the glass defrosters are fed from a 277 panel, how do you group them together?

Ask Iwire he does more installs that may present this problem.

The ones I have done were always 120 volt or 120/240, 120/208, and all fed from same panel, or possibly even all on same breaker.

I think it is also becoming more popular to defrost via pumping hot gas (reversing the refrigerant flow) through the coil than to use an electric heating element which helps out with this issue.

 

[charlie b]

For instance, if the lights are fed from a 120 volt panel and the glass defrosters are fed from a 277 panel, how do you group them together?

By placing the two panels side-by-side.

 

[iwire]

By placing the two panels side-by-side.

:lol:

Much easier said than done.

Typically the cases I work on may have circuits from four or five panels and control circuits from a control panel.

 

[kwired]

:lol:

Much easier said than done.

It is always easier said for the PE than done by the installer:happyyes:

 

[iwire]

Ask Iwire he does more installs that may present this problem.

The ones I have done were always 120 volt or 120/240, 120/208, and all fed from same panel, or possibly even all on same breaker.

I will ramble a bit here, my experience is with larger, chain type supermarkets and what I see likely differs from small stores. In small stores things are more likely to be self contained or at least each case will be independent from the others.

On the other hand the systems I work on are generally all linked together.

The cases will share compressors, controls, condensers etc.

A typical set up like this

Is made up out of many individual cases, often each case is four or five 'doors' each group of 10 to 15 doors will be on separate electrical circuits.

In the frozen aisle you will commonly have:

1) A ligting circuit, often from a contactor controlled lighting panel

2) A fan circuit, often from a panel of just other fan circuits

3) An anti-condensate circuit that often comes from another panel of just anti-condensate circuits and usually run through solid state controls that pulse the feed based on store humidity levels to save power.

4) Electric defrost circuits, these may come directly from a panel board or from a refrigeration control panel

5) Control circuits, they seem to all be going low voltage but many are line voltage

6) Solenoid circuits are sometimes needed from the refrigeration control panel

I think it is also becoming more popular to defrost via pumping hot gas (reversing the refrigerant flow) through the coil than to use an electric heating element which helps out with this issue.

First off, for those that do not know, all the refrigerated cases go through defrost cyscles 2 to 4 times a day. There are 3 ways I am aware of that this is accomplished

1) Off time. It is what it implies, the refrigeration is simply shut down for 30 - 45 minutes. (This is used on medium temp cases, not frozen)

2) Reverse gas. The refrigerant is re-routed and the cold coil in the case becomes hot melting the ice off of it.

3) Electric Defrost. Literally electrical heating elements are placed under the evaporator coils and the heat from them melts the ice.



My experience is that reverse gas is going away, but it seems to be very much a design issue and it's like asking if Ford or Chevy is better.

To my mind reverse gas makes sense, it puts the heat right into the iced up evaporator coil and only really requires a reversing valve installed in the refrigeration lines.

On the other hand electrical defrost adds a lot of cost to the installation of the equipment, more circuits, often 30 amp 208 volts, more contactors and controls.

When I have asked refrigeration contractors why reverse gas is being used less they tell me it tends to cause leaks due to the expansion and contraction that takes place to the piping when the hot pipe goes cold and the cold pipe goes hot.

Anyway ... I have to go to work, I am spending the night in a Supermarket.

 

[GoldDigger]

I will ramble a bit here, my experience is with larger, chain type supermarkets and what I see likely differs from small stores. In small stores things are more likely to be self contained or at least each case will be independent from the others.

On the other hand the systems I work on are generally all linked together.

Anyway ... I have to go to work, I am spending the night in a Supermarket.

The first lesson I take from your description is that although the aisles of doors may be constructed from a variety of standardized parts, they are not the sort of prefabricated self-contained units that would obviously qualify as appliances.
And even for a packaged single case, if the compressor and condenser are remote, I would not necessarily call those appliances either.
Some inspector might want to call them appliances anyway, but that is debatable, IMHO.

PS: Since we are coming up to Halloween, do you have any haunted supermarket stories for the Campfire Chat?

 

[iwire]

The first lesson I take from your description is that although the aisles of doors may be constructed from a variety of standardized parts, they are not the sort of prefabricated self-contained units that would obviously qualify as appliances.
And even for a packaged single case, if the compressor and condenser are remote, I would not necessarily call those appliances either.
Some inspector might want to call them appliances anyway, but that is debatable, IMHO.

We have some cases apart now, I will see if I can look at the listing and see what category they are.

PS: Since we are coming up to Halloween, do you have any haunted supermarket stories for the Campfire Chat?

All I will say is even the cleanest supermarkets have horror shows under the cases.

 

[iwire]

Here is what the UL tag says

"LISTED COMMERCIAL
REFRIGERATOR
AND/OR FREEZER
LESS CONDENSING UNIT
177G"​

 

[GoldDigger]

Here is what the UL tag says

"LISTED COMMERCIAL
REFRIGERATOR
AND/OR FREEZER
LESS CONDENSING UNIT
177G"​

There may still be a grey area as to whether they constitute an Appliance under NEC

...normally built in standardized sizes or types and is installed or connected as a unit...

If they do meet that criterion, then you may have to run a web of strings connecting breakers in different panels or something equally absurd to meet the grouped disconnect criterion.
I suppose if the entire aisle or row is considered one "appliance" then you could group the disconnects by having one motor panel, one lighting panel, etc. for each aisle placed compactly together and call it a grouping.
But once you put several aisles on one panel, the grouping becomes pretty tricky.

PS: The more I think about it, the more I would say that an individual case section would not be an appliance, but the whole aisle might be.... Or at least the whole part of the aisle that shares the same air space inside the doors.

 

[iwire]

The thing is, from a real world standpoint under the standard practices and current rules it is almost impossible to kill all the circuits without a circuit tracer and a lot of time.

Further complicating things is the fact that many times the units are used as raceways to the next units.

So the circuits for a the entire row may enter at one end with many circuits just passing through.

I have gone to a number of service calls where the FD has shut down the entire service and closed the store because the could not locate the branch circuits to kill a particular unit.

This happens when fluorescent lamp holders burn up or the electric defrost burns up wiring or trash that fell into it.

Lots of smoke and smell, no real danger but the FD being a cautious group freaks out and wants to shut down everything.

 

[Little Bill]

Anyway ... I have to go to work, I am spending the night in a Supermarket.

So you are already picking out your supper? Let me guess...."Hungry Man TV Dinner"
and "Haagen Dazs" ice cream?

Just set the TV dinner on one of the compressors.:lol:

 

[kwired]

The first lesson I take from your description is that although the aisles of doors may be constructed from a variety of standardized parts, they are not the sort of prefabricated self-contained units that would obviously qualify as appliances.
And even for a packaged single case, if the compressor and condenser are remote, I would not necessarily call those appliances either.
Some inspector might want to call them appliances anyway, but that is debatable, IMHO.

PS: Since we are coming up to Halloween, do you have any haunted supermarket stories for the Campfire Chat?

Art 100 Definitions:

Appliance. Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, and so forth.

Why is is not an appliance? They are built in standard sizes, they are installed/connected as a unit to perform a function.

Next question is what do instructions say that go with the listing. I have hooked a few of these up myself, never seen any instructions other than what may be on nameplates or limited instructions on a warning tag or sticker or something similar.

If it is not an appliance, what section of NEC applies?