Manufactured Mechanical Rooms - Roof Mounted

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robva

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Hi All

I have a manufactured mechanical room that includes supply fans, return fans, outside air fans, circulator pumps, lights, receptacles, ddc panel and freeze protection heaters.

The unit will be provided with variable frequency drives for the motors, each with line and load side switches.

All of the elements will be field wired - the assembly will come with conduits to a junction box.

Note that there is no compressors within the unit.

I believe this is a Motor Operated Appliance per 422.11 (G) as supplemented by 430 with 422 taking precedence if 430 is less strict.

And, I currently do NOT beleive this is a ROOM as identified by the IBC, specifically as the Architect will not certify the assembly as a room relative to projects buidling classifications.

I also believe that I need to disconnect the assembly prior to anyone openning the door.

Yet, I can not find any specific statement supporting my belief.

All thoughts are appreciated.

Best Regards
RobT
 
Rob,

I'm having a hard time with, Motor Operated Appliance, it might be good to have a disco.

before opening the door but I don't believe it's NEC requirement. It's just a big room with

fans in it ! No manafactures instructions with this thing?
 
Sounds interesting, is the "room" listed? Or does it have a nameplate?

Otherwise, I don't really see how I would treat it differently than if it had been built in place, with the exception of grounding. (?)
 
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I would not consider this an appliance or even a motor or motor driven apparatus.
We are seeing quite a bit of manufactured items as you are speaking of, not just on roofs, but installed in all portions of buildings.


Here is an example of one that is on a job I am inspecting. It is a refrigeration unit preassembled at a plant and shipped to the job. It is then put in position via a crane.
BJs-550941.jpg
 
Its all in the engineering stage, from the HVAC guys. And, no UL Listing either. Everything is field wired.
 
robva said:
I believe this is a Motor Operated Appliance per 422.11 (G) as supplemented by 430 with 422 taking precedence if 430 is less strict.
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I think it is a space with varied utilization equipment located within.

robvaI also believe that I need to disconnect the assembly prior to anyone openning the door.[/QUOTE said:
If once you stepped inside the door it was all exposed live parts (as if you where inside a real 'appliance) then I would say you need a disconnecting means outside. However it is essentially a room wired to the requirements of the NEC so it is safe to be inside the room with the power on.

TOOL_5150 said:
so thats what those things are on top of food stores.
Click to expand...

Yes and many are a 'double wide'. :smile:

The ones I work in typically have the the service gear, distribution, energy management systems, refrigeration equipment, water heaters, emergency generators, phone board, PA systems all in place and ready to be connected to the building.
Click to expand...
 
iwire said:
Yes and many are a 'double wide'. :smile:

The ones I work in typically have the the service gear, distribution, energy management systems, refrigeration equipment, water heaters, emergency generators, phone board, PA systems all in place and ready to be connected to the building.
Click to expand...


I saw a pretty big one on top of a safeway food store. It looked like one of those 53' trailor mounted cat generators. That seems like a really good way to speed up production and allow the store to open faster rather than plumbing, wiring as well as installing all the equipment into into the store itself.

Hopefully some day soon I can get some commercial experience. Right now, Im happy with getting 16 hours in a week.

~Matt
 
This is becoming fascinating! And, thanks much for the interest. Currently I am hearing both sides of the issue. Many (on this forum and my other colleagues) agree that it should be treated as a room. Some believe if there are live parts, then a disconnect is needed outside. Others say, that be cautious and have the switch outside. Yet, so far, no one is able to point to specific standard to use.
 
Ongoing...

Ongoing...

Live parts could include wiring to the damper motors, the control circuitry, and to any individual extra components, including any louver damper assemblies. Yet, this might be over reacting a bit.

Here's another perspective from a local engineer:

Rob,

I argue that the ?machine room? is a controller for the unit and houses group of devices for the controls of internal components of the unit.

Refer to article 430 - I

NEC 430-101 requires disconnecting means capable of disconnecting motors and controllers from the circuit. The circuit in this case will be feeder to the unit.

See figure 430-01.

NEC 430-102 requires this controller disconnecting means to be located in sight from the controller location.

NEC 430-107 requires ?one of the disconnecting means to be readily accessible.

Refer to definition of readily accessible.

Accessible (as applied to equipment) "Admitting close approach; not guarded by locked doors, elevation or other effective means"

The units door is lockable

My friend makes a compelling case.

Rob
 
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