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#167515 - 08/14/07 08:04 PM Light fixture support  
sudsy4  Offline
Member
Joined: Apr 2002
Posts: 32
Elizabeth,PA USA
I'm installing 8 ft plug in fixtures in a large retail commercial building (28 per row). Is there any spec as to the spacing of supports?


Bill

Work Gear for Electricians and the Trades

#167533 - 08/15/07 06:06 AM Re: Light fixture support [Re: sudsy4]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,874
Brick, NJ USA
Best answer may be:
Check mfg specs
or
Apply common sense.
8' fluor channel fixtures are surface mounted at 3 points; suspended at 2 points (each fixture)
It's a 'no definite' answer as the layout is vague by your description above.


John

#167537 - 08/15/07 06:35 AM Re: Light fixture support [Re: HotLine1]  
ITO  Offline
Member
Joined: Nov 2006
Posts: 348
Texas
The only rule I know of is 110.3 (B)...well that and 110.12


101° Rx = + /_\

#167539 - 08/15/07 06:44 AM Re: Light fixture support [Re: sudsy4]  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
With hanging 8' strip lights I usually support the first one at both ends and the far end of each succeeding one.

Here is a job I finished last year, almost 600 fixtures.

[Linked Image]

That said I recently hung some 8' custom linear lights in offices and that jobs foreman had me do the same as I described above. IMO the fixtures being cast where to week for that and should have had three supports a piece for each fixture as they had been designed.

I guess what I am saying is follow Johns advice.....apply common sense. smile


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#167576 - 08/15/07 06:46 PM Re: Light fixture support [Re: iwire]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,874
Brick, NJ USA
Bob:
NICE....
BTW, quite a while back...like you said, 2 on the first; chase nip/ln thru end ko's, one on each additional.
I didn't want to write a novel on the many ways....
Now the 'old' 8' INdustrial type with the full reflector shade...nice old heavy mag ballast, and a housing made from real live steel, not recycled Pepsi cans (man's fixture), that was a definite 'two chainer'.

Back to my serious mode....any shot to get good old common sense into the NEC??

Stay safe


John

#167584 - 08/15/07 09:23 PM Re: Light fixture support [Re: sudsy4]  
sudsy4  Offline
Member
Joined: Apr 2002
Posts: 32
Elizabeth,PA USA
Thanks for the input everyone. I agree on the 2 on first fixture then one a foot or so from the end of all the rest; however, bar joists don't fit that senario. I guess my actual question was can you miss a hanger on a fixture or must you have a support on every fixture? Checked manufactures specs, told me nothing. The store is a Wal-Mart Superstore.....many many fixtures.


Bill

#167585 - 08/15/07 09:28 PM Re: Light fixture support [Re: iwire]  
sudsy4  Offline
Member
Joined: Apr 2002
Posts: 32
Elizabeth,PA USA
Thanks for the pics...nice job


Bill

#167604 - 08/16/07 06:28 AM Re: Light fixture support [Re: sudsy4]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,874
Brick, NJ USA
Bar joist locations not 'matching' a place for a support are solved by bridging b'twn bar joists with strut, or another suitable alternate.
What about the plans/specs? Most, if not all will provide a detail on the REQUIRED method of installation by the Architect/Engineer of record.

Your 'client' is not a small operation, so you should have details available, or submit an RFI.


John

#167617 - 08/16/07 02:52 PM Re: Light fixture support [Re: sudsy4]  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Originally Posted by sudsy4
I guess my actual question was can you miss a hanger on a fixture or must you have a support on every fixture?


I would not skip a support, as John mentioned you need to come up with a way to get a support where you need it.

In my picture above out of over 600 supports only a few actually land on a truss. If you notice the fixtures are diagnal...a major pain in the rear.

Anyway we used these from Caddy...

[Linked Image]

[Linked Image]

To install most of them you use this tool...

[Linked Image]

But before we got started I sent an RFI to the engineer asking if this method of supporting from the deck was OK. He approved it and away we went.

I can tell you these are very strong.

BTW, also the fixtures in the above photos are joined with factory couplers with 4 tek screws added per coupling to ensure the fixture could not pull apart and drop.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#167632 - 08/16/07 06:17 PM Re: Light fixture support [Re: iwire]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,136
Estero,Fl,usa
How does this grab the deck?


Greg Fretwell

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