Refrigerated Trash room

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dcspector

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Burke, Virginia
I came across something today I have not seen to date. A refrigerated trash room. This enclosed room is located adjacent to the loading dock in a typical mixed use occupancy high rise. The walls are CMU up to concrete deck at ceiling. The refrigeration unit ceiling mounted resemble that of a walk in cooler type. The wiring methods are exposed EMT and FMC to the unit and with set screw connectors, the disconnect for the unit is NEMA 3. Also, the 4 square box (slang term 1900) for AV FA device is standard dry only, luminaire dry only as well. Mechanical Contractor was not on site for information. I did not turn the installation down, just simply quoted section 314.15 and 410.10(A) untill I find out what condition this unit will render....damp? Has anyone dealt with this type of conditioned space before?
 
Is a cooler not a dry location? It may be colder than some other room, but so is a garage. Check the rating on the luminaire, most major mfgs. damp rate all of there fixtures, it is not common to find a "dry rated" fixture that would be used in this case.
 
DRGREG said:
Is a cooler not a dry location? It may be colder than some other room, but so is a garage. Check the rating on the luminaire, most major mfgs. damp rate all of there fixtures, it is not common to find a "dry rated" fixture that would be used in this case.
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Well I look at definition of Damp last sentence and they will be washing this room down in the future that could be a wet location. On that note I am not a "what if inspector" but I am looking at this all around. Also, a cooler as in walk in is not a dry location. The thermostat on this particular unit can be set at 38 degrees and max. 55 degrees. I see condensation and this is a damp location.
 
DRGREG said:
No, by its nature cooling the air removes moisture. Depending on use moisture is introduced just as it is in any other area.
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True, but any air that leaks in will have mositure condense on the first cold surface it finds. I would expect that to include the inside of the light fixture unless they put duct seal in the conduit.

Some people will put fire alarm annunciators anywhere. :rolleyes:
 
I just got off the phone with the designer (1:35 pm) The unit is designed to actually freeze the trash room to prevent rodents and odors (makes sense). Yes! it is subject to wash down and severe condensation due to opening and closing the door as in a walk in freezer. So yep! here we go as I suspected.They (design team) want wet location equipment in the room and said thanks for bringing that to their attention. Oversight on their part for not specifing that on the plans. Thanks DRGREG and Steve.
 
Are the cooler/freezer evaporator units wet location rated? Most of the units I have seen have ODP (open drip proof) motors and would not withstand wash down. Wash down will not make any part of the system easy to install. NEMA 4 or 4X may be required.
 
Temperature should not be a consideration, relative humidity will be of concern. Since they will not be concerned with dehydrating the garbage the refrigeration system could be designed with a lower evaporator temperature inturn drying the air more.

DC Greg- This is what makes our jobs FUN.
 
dcspector said:
I just got off the phone with the designer (1:35 pm) The unit is designed to actually freeze the trash room to prevent rodents and odors (makes sense). Yes! it is subject to wash down and severe condensation due to opening and closing the door as in a walk in freezer. So yep! here we go as I suspected.They (design team) want wet location equipment in the room and said thanks for bringing that to their attention. Oversight on their part for not specifing that on the plans. Thanks DRGREG and Steve.
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Well, the washdown removes any question about it being a wet location.

I'm really wondering if freezing the trash will keep it from smelling, or if the freezer will just lock the odor in enough to really make it unbearable when someone opens the door.

And if there is a way for rodents to get in and out, I don't think the temp will slow them down either.

Of course, none of that is your problem.

Steve
 
dcspector said:
Bob this has turned into a walk in freezer so to speak.....thoughts?
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My thoughts are that it is not a damp location, all the factory wiring will be dry location type methods.

In my area it seems 'traditional' or in the specs to use bell boxes, liquid tight and compression fittings. But here is what I have found from servicing this equipment. This does more harm then good, if moisture gets in the conduits*** it collects in the boxes destroying the box and device or wire nuts.

*** The moisture that I do find can ALWAYS be traced back to insufficient or non-existent conduit sealing from the heated area to the cooled area as directly required by 300.7(A).

If I had my way I would use normal dry location wiring methods (assuming no wash down) and seal the heck out of the raceways where they pass from one area to the other.

IMO inspectors would be doing the customer a lot of good if they really enforced 300.7(A). :smile:
 
iwire said:
Why would a room that is dehumidified be considered 'damp'?
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'
Wouldn't it be just like a freezer? Eventually there will be ice on the walls? And there might even be a defrost cycle and a heated floor drain?


Steve
 
Bob, Steve, Greg

Great points! I am confused and glad I did not cite the install. Gut instinct said no and wanted to here from ya'll about this. The design team is preparing an RFI to correct but I am not persuing this nor did I cite it(repeat) simply verbal. Thanks all for your thoughts and professional input.
 
iwire said:
My thoughts are that it is not a damp location, all the factory wiring will be dry location type methods.

In my area it seems 'traditional' or in the specs to use bell boxes, liquid tight and compression fittings. But here is what I have found from servicing this equipment. This does more harm then good, if moisture gets in the conduits*** it collects in the boxes destroying the box and device or wire nuts.

*** The moisture that I do find can ALWAYS be traced back to insufficient or non-existent conduit sealing from the heated area to the cooled area as directly required by 300.7(A).

If I had my way I would use normal dry location wiring methods (assuming no wash down) and seal the heck out of the raceways where they pass from one area to the other.

IMO inspectors would be doing the customer a lot of good if they really enforced 300.7(A). :smile:
Click to expand...

I have done many conduit installs in "Cold Rooms". I do
a lot of service work for Pharmaceutical Companies.Most labs
have "Walk-INs" I don't care what wiring method you use.
Wet,Damp,Underwater,whatever.If you don't PROPERLY
seal EVERY conduit where it enters the "Cold Enviroment"
IT WILL FAIL.LT.EMT,RIDGID,Compression,set-screw,etc
Even if you use FNMC as IWIRE said the wirenuts will rust
and the BEll Boxes will be full of water in a short amount of time.
 
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