I've got a job wiring a refrigerated walk in building. The Building is approx. 40 ft. X 12ft. It has 2 3 phase outside compressors (240 volt) and 2 1 phase evaporators inside with 3 fans each, and also I'm to wire 120 volt circuit for lights and door heater. I already have a 200 amp. 3 phase 30 circuit pole service that was erected for freezer trucks to plug into. As long as I put the required disconnects for the compressors and evaporators etc., can I not just pull straight from the existing service to the building via junction box etc. providing all the right sizing and overcurrent protection and not have to set another panel on the building itself?? I think I'm right but want to see if I might be missing something per Code. Since the service is not attached to the building, does this present a problem? The existing service is only about 12 ft. from where the building is to be located. The existing service is mounted on 2 X 6 treated lumber that is attached to 2 4X4's ( treated also ). This will be about the same scenario as a mobile home service.. Thanks for your input.....
This might be a bit off, however do you think an emergency light might be required? If this is a total walk in building, and if the power goes out, you might need the emergency light to find your way out of there.
Re: Walk in Refrigerated Building#17775 12/02/0210:04 PM12/02/0210:04 PM
I would consider the following: 1. If you size a feeder, run it from the existing service to the walk in building, set a panel, or gutter, and run your branch circuits from the panel, or tap the gutter, you will (as long as the panel has a main, and you set OCP at the gutter) effectively eliminate the situation that Don has pointed out above. I wouldn't take what Don says lightly, he, from what I've seen, "knows his stuff". 2. Doing it this way will allow the building to be moved in the future by disconnecting the feeder, and "hitting" it with a new feed at it's new location. It makes the building a "self contained" unit. 3. Unless you run the branch circuits from the existing service in separate conduits, you will have to derate the wire. 4. Remember your "within sight of" rules for disconnects.
"Walk in" through the "out" door, Doc
The Watt Doctor Altura Cogen Channelview, TX
Re: Walk in Refrigerated Building#17777 12/04/0208:30 AM12/04/0208:30 AM
Don Thanks for the information. You were exactly right about the sub panel... checked with the AHJ .. said the same... like to get some of my facts together before going to them though That was my first thoughts, then I when I really started thinking, is where I missed it Thanks again,,Doc was right, you know your stuff