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#97918 - 04/14/06 02:10 AM freezer coil disconnecting means  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
I have a walk-in freezer/refer with a fan coil hung from the ceiling in the freezer side. The freezer/refer is a prefab modular unit. You have to walk thru the refer to get to the freezer. They want a defrost
clock and fused disconnect in the electrical room about 5 feet away on the outside of the freezer. There are 5 conductors going to the 240V fan coil to control the defrost elements and fan motors from the clock. What
are the options for providing a disconnect for the fan coil? Do I need a 5 pole disconnect in the freezer?


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#97919 - 04/14/06 05:03 AM Re: freezer coil disconnecting means  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
We usually use two separate disconect switches.

One for the fan power and the other for the defrost power.

Most times these are low current applications (under 30 amps) so we just use 1, 2 or 3 pole toggle switches in weather proof boxes.

No need for fused disconnects inside the chest.

[This message has been edited by iwire (edited 04-14-2006).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#97920 - 04/14/06 07:52 AM Re: freezer coil disconnecting means  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
In some situations these evaporator units have a cord/cap type hook up inside the unit that should be acceptable as as disconnect. IMHO. Of course you'd still need a disconnect within sight of the controller what and where ever it might be located.


George Little

#97921 - 04/14/06 11:38 AM Re: freezer coil disconnecting means  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
I was thinking it had to be one simulatious
disconnecting means. two switches solves the problem. I have seen weatherproof boxes full
of condensation inside walk-ins. Is there any reason not to use conventional 4S boxes?


#97922 - 04/15/06 07:18 AM Re: freezer coil disconnecting means  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Quote
I was thinking it had to be one simulatious disconnecting means.


As long as the switches are 'grouped' it is no problem.

Quote
I have seen weatherproof boxes full
of condensation inside walk-ins.


[Linked Image]

Yes that is a common problem and it is caused by failing to comply with 300.7(A)

Quote
300.7 Raceways Exposed to Different Temperatures.

(A) Sealing. Where portions of a cable raceway or sleeve are known to be subjected to different temperatures and where condensation is known to be a problem, as in cold storage areas of buildings or where passing from the interior to the exterior of a building, the raceway or sleeve shall be filled with an approved material to prevent the circulation of warm air to a colder section of the raceway or sleeve. An explosionproof seal shall not be required for this purpose.


If 300.7 is ignored you will get water.

Quote
Is there any reason not to use conventional 4S boxes?


No not really.

For my work it is usually a customer requirement.

But it is not a problem if you follow 300.7 and make a small drain hole in the box all is good.

Just trimming a notch in the covers gasket at the bottom is enough to make sure the box does not fill with water.

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#97923 - 04/17/06 10:33 AM Re: freezer coil disconnecting means  
wewire2  Offline
Member
Joined: Nov 2002
Posts: 244
California
Thanks. You guys are great. I appreciate the input.



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