walkin coolers

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iwire said:
Same here, unless they are prewired knocked down units that I have wired once assembled that use dry methods.

The inspector did not like it and told me he would fail it, he called the manufacturer and changed his tune it passed fine.

Keep in mind the NEC is not as restrictive as many believe it is.

As an example FMC can be used in wet locations, the key is using conductors rated for wet locations.

If anyone here thinks that using wet location methods in a cooler will keep the conductors dry if the space is indeed damp I have seafront property in death valley for sale.
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Its usually in our specs.One of our freezer builders wont even allow pvc conduit under the slab of a cooler.That can add to cost.Same allows compression fitting on emt.Will that keep water out ? not likely.
 
Watch out for Sanitary Issues

Watch out for Sanitary Issues

A walk-in cooler, especially when used for storing food (as opposed to, say, beer & soda) ought to be given extra consideration.

The real gremlin here is the "health code", or, more importantly, how it is applied locally. Coolers used for food need to be cleaned; this might very well be with a hose. Or a wet mop on the wall,

At the minimum, mineralacs ought to be used to keep the pipe off the wall and ceiling itself; this will allow cleaning behind the pipe, and prevent crud from collecting there. SOME places want the pipes farther off the wall; plumbing houses sell plastic stand-offs for this purpose.

Also for the purpose of cleanliness, the use of Bell boxes is reccomended.

Finally, the NEC does expect you to seal the conduit where it penetrates the wall. Duct seal is one method to prevent outside moisture from entering the pipe, and condensing there.
 
georgestolz said:
So here's a question: should the NEC carry special requirements for the health safety of walkin coolers?
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No, the health codes, where they have the force of law, already do a fine job of that.
 
benaround said:
I agree that the humitity goes down, but how, by removing heat does it do it????
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Quick physics lesson:

There's a difference between absolute humidity and relative humidity. Absolute humidity is simply the amount of water vapor in the air by volume, usually expressed in weight (or volume) of water per volume of air.

A specific amount of water vapor is a different relative humidity at different temperatures. As you lower the air temperature, a given amount of water vapor becomes a higher relative humidity; when you hit 100%, condensation occurs.

For any given air temperature, there is a specific amount of water vapor that the air can hold before condensation occurs. This is 100% relative humidity. The amount of water that this represents varies with the temperature.

Also, the dew point is the temperature at which a given absolute humidity becomes 100% relative humidity. If you reduce the amount of water vapor, the dew point drops. If you cool the air, water vapor condenses.

This is what happens in coolers; cooling the air causes condensation, which becomes liquid water, and drains away (hopefully). If you re-warm the air, you have a lower relative humidity at the beginning temperature.

The reason static electricity is worse in the winter is that, as you warm the air inside the house, the relative humidity drops. There is less water vapor in the colder outside air that infiltrates, so the absolute humidity is low.
 
Walkin coolers

Walkin coolers

Actually, George, the NEC does reference the subject, if somewhat indirectly. The NEC calls for a 1/4" gap where the place is intended to be 'washed down.'

In a similar situation, the Fire Code (ICC) requires the 'egress path' to have backed-up lighting. In effect, now the outside lights near the exit doors have to be battery back-up types. These are not cheap lights, either!

The 'similarity' is that, in both cases, our work is strongly influenced by codes other than the NEC. It's our duty to know these codes.

I got a lot of my earlier experience working in packinghouses. So, when the need later arose for me to wire a walk-in cooler, I "just did it." Now, in some details, my practice was ever-so-slightly different from what the HVAC guy had seen before. Feeling full of himself, this cretin waited until I was putting in the very last screw to tell me where I 'went wrong.' Code, he said.

Little did he know .... the next morning, I came in, having already visited the Health Department, and had my part signed off on. Indeed, the Health Department almost went into shock, when I walked in carrying a copy of their code! I don't think they had ever seen a contractor who actually owned one :) The playful HVAC guy .. who had assembled an audience to witness my humiliation, had his plan backfire. Poor baby! :D
 
renosteinke said:
Actually, George, the NEC does reference the subject, if somewhat indirectly. The NEC calls for a 1/4" gap where the place is intended to be 'washed down.'
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John, is that to minimize bacterial buildup or to protect the raceways and enclosures from damage? :)

Good story, BTW. :cool:
 
walkin coolers

DC, you are correct, I was referring to 312.12(A).

Strictly speaking, this only addresses the enclosures, and says nothing about the pipe. The NEC gives as a reason 'to prevent moisture from entering.'

Most places follow the USDA rules, which simply specify that all pipes will be supported off the walls, etc., for cleaning purposes. Just what is meant by "off the walls" is open to some debate; usually mineralacs are enough. It's a point worth checking out before you run the pipe, though.

I agree that there is a trade-off here; mounting the pipe away from the walls does seem to make it more likely to get damaged.

As for the use of Bell boxes .... again, I like the cleaner profile. Fewer nooks and crannies to catch crud ... and better to have when the janitor comes around with his squirt bottle. This is why I'll sometimes install a "Bell Box" yet still use an ordinary coverplate; "wet location" is not required, but I want the clean look.

For a similar reason, I will use a Bell Box outdoors, even in a sheltered location. One does tire of finding spiders and wasps inside the boxes. You try to remove the cover ... and see six little legs pulling the cover back on!
 
For conduits look at 300.7 (A) - An enclosed cooler and the surrounding building envelope are of differing temperatures. Typically a walk in freezer can be as low as -25 deg F, coolers in the 40 deg F range. Because of these requirements RTV silicone around the outside of conduits and foam in place sealant on the inside are mandatory for any of our supermarket projects. It certainly makes sense to follow this requirement as it prevents the steady ingress of warm moist air and does not denegrate the efficiency of the refrigeration system.


I would certainly consider walk in coolers and freezers damp/wet locations. During normal everyday operation its commonplace to load in, therefore an extended time period with the door open. This allows plenty of warm air to enter. As soon as you close the door and the system begins to lower the temp back down the moisture in this air will condense, usually onto anything at the lower temperature. Also, gasketed light fixtures tend to cool and draw the moisture inside the fixture body. There is definately moisture present, which condenses into its liquid form.
 
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