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#88364 - 05/29/04 06:30 PM Electrical Equipment on Roof Tops
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
I would like to discuss some of the rules as they related to the NEC and other codes that may be applied on the roof top of this multifamily dwelling.

_________________________
Joe Tedesco, NEC Consultant

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#88365 - 05/30/04 06:32 AM Re: Electrical Equipment on Roof Tops
DougW Offline
Member

Registered: 06/08/03
Posts: 1083
Loc: North Chicago, IL
As a firefighter, I think of having a fire in a room, or the cockloft under those A/C units. With the damage to the structure, and the building not being designed for the load, having one of those come down on us is a real possibility.

As an EC, do you have any closer pics for us Joe? And which articles are you thinking of in particular?

The one which first pops to mind for me is about having a 15 or 20A GFCI protected "Heating, Air-Conditioning, and Refrigeration Equipment Outlet" on the rooftop, per 210-63 ('96 NEC).

Edited to add - just looked at my NEC - sorry!


[This message has been edited by DougW (edited 05-30-2004).]

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#88366 - 05/30/04 06:44 AM Re: Electrical Equipment on Roof Tops
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
210.63 is the section that requires the outlet for servicing the equipment.

It requires the outlet be within 25' of the equipment, so in Joe's picture there should be a few outlets at least.

As far as the roofs being designed for the weight of the equipment that is considered / required.

I doubt a structural engineer is involved when it is a small unit that would be the equivalent of a couple of people standing on the roof.

The roofs under large units must be built for it.

I was recently in a roof unit on a supper market that was tagged as weighing 18,000+ lbs.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#88367 - 05/30/04 06:45 AM Re: Electrical Equipment on Roof Tops
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
Yes, NEC 210.63 calls for one within 25 feet of the HACR units:

 Quote:
210.63 Heating, Air-Conditioning, and Refrigeration Equipment Outlet.

A 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed at an accessible location for the servicing of heating, air-conditioning, and refrigeration equipment. The receptacle shall be located on the same level and within 7.5 m (25 ft) of the heating, air-conditioning, and refrigeration equipment. The receptacle outlet shall not be connected to the load side of the equipment disconnecting means.

FPN: See 210.8 for ground-fault circuit-interrupter requirements.


Article 440 covers this equipment, and 440.14 includes the disconnecting means rules.
_________________________
Joe Tedesco, NEC Consultant

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#88368 - 05/30/04 06:55 AM Re: Electrical Equipment on Roof Tops
DougW Offline
Member

Registered: 06/08/03
Posts: 1083
Loc: North Chicago, IL
Above post edited after I fetched my NEC.

<>

(Open mounth, insert Code book)

I have seen the mentioned outlets mounted to the equipment frames or support structures.

What about working room requirements? I could see a problem if the D/C's were in the space between the two units.

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#88369 - 05/30/04 07:03 AM Re: Electrical Equipment on Roof Tops
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
closeup




The following gets you back to 110.26 for working space, always a problem in the field because the space is never enough.
 Quote:
440.3 Other Articles.

(A) Article 430. These provisions are in addition to, or amendatory of, the provisions of Article 430 and other articles in this Code, which apply except as modified in this article.


[This message has been edited by Joe Tedesco (edited 05-30-2004).]
_________________________
Joe Tedesco, NEC Consultant

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#88370 - 05/30/04 07:07 AM Re: Electrical Equipment on Roof Tops
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
A big mistake is the disconnect is mounted to the unit on a panel that needs to be removed for unit servicing.

Part of 440.14
 Quote:
The disconnecting means shall not be located on panels that are designed to allow access to the air-conditioning or refrigeration equipment.


Sometimes it is almost imposable to find a mounting place on the unit that is not a removable panel, a condenser coil, a vent for air flow and still provides the 110.26 workspace that some inspectors require and some do not.

Creative use of uni-strut will get you around these issues.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#88371 - 05/30/04 07:12 AM Re: Electrical Equipment on Roof Tops
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
From the looks of the picture
guard rails between the units
and the roof edge may be needed
here.

I believe Ryan has told me the
distance from the roof edge must
be 6' or guard rails required by
building code.

Bob
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#88372 - 05/31/04 03:14 PM Re: Electrical Equipment on Roof Tops
Ryan_J Offline
Moderator

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
Bob is right in that there would probably be a 42" gaurdrail installed, but this proviosion actually kicks in at 10',not 6'.
_________________________
Ryan Jackson,
Salt Lake City

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#88373 - 06/01/04 12:21 AM Re: Electrical Equipment on Roof Tops
Big Jim Offline
Member

Registered: 07/18/03
Posts: 377
Loc: Denver, CO USA
More likely an A/C problem but why would there be a pedestal fan sitting up there pointed at one of the condensing units - trying to cover for a too-small or overloaded unit?
Around here, they have to build for a 30 pounds per sq. ft. snow load. The rooftop units likely are less than that and would not need any special structural consideration beyoun making the penetrations watertite and distributing the loads.

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