KJayI may be able to offer you assistance on this subject.
The Company I work for deals primarily in Cold Storage Warehouses / Logistics Facilities & Processing Facilities, along with a variety of other Industrial Projects.
Cold Storage Warehouses, "Box In Box", & Logistics Facilities range from 2,000 Square Feet to 300,000 Square Feet, with areas such as:
- 40� F Loading Docks,
- 40� to 32� F Coolers,
- Freezers, down to as low as -20� F,
- Dry Storage areas, at Ambient Temperature
We perform Design / Build services for > 90% of the Projects.
My tasks are mostly in the Designs area (Electrical Design / Engineering), but also perform Project Management.
With that being said, let me address your original posted questions. Afterwards I will add some additional things to consider, and a few suggestions.
Will try keeping this posted message as concise as I can!***** COLD ENVIRONMENTS WIRING METHODS & MISC. EQUIPMENT ******** 1: Conduits...
Typically EMT with Compression Fittings is used for Projects without crucial specifications, and in "Non-Washdown" areas.
Evaporators (or Air Units, as sometimes termed) connect with LFMC (Metallic Sealtite) for the Fans' Power Circuits, Defrost Heaters' Circuits, and the Control Circuits.
In areas where Processing is involved + Washdown is daily, either PVC 80 is used, or PVC Coated GRC (AKA: "OCAL" and "ROB ROY").
The Building Department is queried to verify their requirements. Normally, with 480 VAC Circuits, the DBS (Dept. of Building Safety) requires GRC. We use ROB ROY to reduce the issues associated with oxidation.
Lastly, some Clients will specify the use of GRC, ROB ROY, or some "High Dollar" Conduits, such as:
* Rigid Aluminum Conduit,
* Stainless Steel Rigid Conduit,
* Stainless Steel EMT.
As you can see, there are many options for Conduits. All depends on the Client's specifications -vs- the requirements of the DBS.
At minimum, EMT with Compression fittings is acceptable above the lid, or inside the box.
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*** 2: Conductor Insulation...
If the controlled Temperature is 34� F or higher, then THHN Insulation may be used, unless specifications call out differently.
For less than 34� F environments, use XHHW Insulation.
For Sub Zero environments subjected to extreme conditions (high levels of vibration, frequent moving, etc.), the use of Cables and Insulation designed for "Low Temperatures, Extreme Conditions" should be used.
In these areas, "FREP" Cable is used instead of Sealtite with XHHW Conductors.
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*** 3: Disconnect Switches for Evaporators ...
DEFINITELY install local Disconnect Switches at the Air Units (Evaporators). Use lock-off types.
Check the job specs, and any AHJ to determine if NEMA 4X enclosures should be used.
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Some things to consider:
a: Seal-Off any Penetrations between Ambient, Non Conditioned areas, and the areas with Controlled Temperatures - even if the Controlled areas are above 32 degrees F.
This is necessary to avoid building up condensation in the Raceway.
I have a copy of the Seal-Off Details used on our Plans, which may be of great assistance to you. Have some saved as a PDF, and even more Details in .DWG file format.
Seals should be placed on the _WARMER_ side of the penetrated partition.
b: Lighting Fixtures should be designed for Extreme Conditions, and have sealable, gasketed panels.
In areas with Temperatures below 25 Degrees F, best to use an application which heats the Fixture.
With Fluorescent Fixtures (T5 HO), we have the inner 2 Lamps on during working hours, and the outer Lamps controlled via Occupancy sensors.
Avoid using any Instant Start, Cold Cathode Lamp Operations, and "Standard" output Lamps (420 ma).
Go with HO (High Output / 800 ma) Lamps, driven by Programmed Start, Hot Cathode Ballasts.
Additionally, in subzero areas, the output lumens of Fluorescent Fixtures will be dramatically reduced (same as extremely warm areas). When designing a Lighting layout, increase the desired average Foot-Candles by 15 to 20%.
c: In Freezers, there may be Floor Heat applied via Heat Trace Cables. This requires certain design criteria.
Along with Floor Heat, Man Doors + Lift Doors will have Heat Strips internal.
d: Evaporators may be Defrosted Electrically - via internal Heater Elements, or via "Hot gas".
With most Electric Defrost Heat, the Fans and the Heaters are different Circuits, fed separately - but from the same C.U. / Rack.
In these cases, Two (2) separate disconnects will be mounted to the A.U.s (Air Units).
e: Drain Lines from the A.U.s may require Heat tape, with appropriate Circuits.
Normal figures use Self-regulating Heat Tape, rated at 6 Watts per foot, in Voltage ratings of 120, 208, 230, and 277 Volts.
Typical wrap patterns on 2" Drain Lines increases the Linear footage by 141%. This should be verified prior to Circuiting the Drain Heat.
f: Surface mounted Outlet boxes, used in 40 degree and lower areas, should be something with a hub - such as Bell Boxes, FS Boxes, and similar.
If at all possible, mount devices outside the box, and where a NEMA 4X rating does not apply.
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That's all for right now.
Let me know if you have specific questions, if you would like some more information, or if you would like a copy of Penetration Details.
Reply either directly to the thread, via P.M., or by E-mail.
Good luck.
Scott
