Does anyone know of a building code requirement for seismic wires to limit the swing of pendant mounted light fixtures? This is not in T-Bar, just an open ceiling but the jack chain that suspends the high bay 2x4 fixtures can hit the HVAC duct in some places. I am in CA and I know that there is a DSA requirement for schools that says if the fixture can swing and hit an obstruction within 45 degrees in any direction then the seismic wires are needed, but this is for a commercial building. Anyone know a code section that would require seismic wires?
Seismic Wires for Pendant Light Fixtures
- Thread starter mwslo
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- Location
- Simi Valley, CA
That's a hard one to answer. You would be best talking to your local AHJ. You can limit the swing, but in reality you would need 4 cables and even then how do you limit the bounce, which happened during the '94 earthquake?
We just kind of gave up out here in my town.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
yeah... they called it the northridge quake, but i suspect you called it the "too damn close" quake.
btw, what kind of lag bolts do you use now to keep your freeways from bouncing?
i remember the civil engineer being interviewed...
saying they designed for the sway, it was the bouncing that surprised them.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Ya all know that '89 in SF was not fun either. I was near the marina, 1 block off Lombard and Filmore.
- Location
- Simi Valley, CA
Yeah, at the time we were really only about 5 miles from the epicenter.
We had buildings that the roofs fell in on and the engineers said the same thing about the "uplift" and not really designing for it, which is why we now have square washers in the building code for the sill plates, among other things. The mountains around us are now 12-24" taller than before the earthquake. We learned all kinds of things after that one. When it hit I swore that a bomb had gone off in my garage, it shook that hard. They say what happened was that the shock wave hit the sandstone mountains, that were about a half mile from my house, and that compressed the wave, then when it came out on our side it just went off like a rubber band snapping back.
Seismic Wires
Seismic Wires
I think my question got hi-jacked by earthquakes. I can't find any requirement in any building code. Anyone familiar with the UBC or the CBC, etc. that can weigh in on this? We have about 100 of these fixtures to hang with all kinds of HVAC ducting in the way. Nobody has mentioned anything about needing the wires yet, I just don't want to have to go back later to add them in. If they are required, I'd like my foreman to get it right the first time.
Seismic Wires
I think my question got hi-jacked by earthquakes. I can't find any requirement in any building code. Anyone familiar with the UBC or the CBC, etc. that can weigh in on this? We have about 100 of these fixtures to hang with all kinds of HVAC ducting in the way. Nobody has mentioned anything about needing the wires yet, I just don't want to have to go back later to add them in. If they are required, I'd like my foreman to get it right the first time.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
John answered you in post #2. I believe that CA allows local amendments, so ask the inspector/AHJ.
- Location
- Simi Valley, CA
What exactly did you think that a siesmic event was?
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Was I correct about local amendments to the state code?
- Location
- Simi Valley, CA
Yes sir. Los Angeles used to have some pretty strict ones. Here if you put it in the suspended ceiling you need to put a seismic wire on it and we don't care how much it weighs.
I don't, as a rule, worry to much about what other cities are doing, so I don't have copies of their local stuff.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
well, that explains the name jumper, and why you are on the other coast now.... ;-)
to the original poster, californicaters talk about earthquakes, and traffic. we weren't trying to be rude.
our stories disclose in a general way what it was like, what happened, where we were stuck in traffic at.
it's a cultural thing.
i'm a c-10 in socalif. and i've never gotten dinged on the sway thing. everything needs a seismic wire, and cable tray and other substantial
items need sway bracing, and i'd just ask the inspector what he wants to see, and if it's reasonable, do it.
my experience with inspectors is that they don't sign off stuff they don't like, and if you win the argument on fine points in the NEC or UBC,
it's quite easy for them to inspect away any profit you might expect to make on the job. i've found it's a battle not worth winning, literally.
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jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Yeah a lot of good that did, last month we had that little 5.8 quake out here right before Irene graced us with her presence.
People here freaked, most have never been rattled before.
- Location
- Simi Valley, CA
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
today, i was putting in power for an exhaust fan in a college, in californicate.
there were suspended four tube t5 HO luminaries. they were sway protected within an
inch of their lives.
they were cable hung with 1/4" gal cable, and three clamps top, and three clamps bottom.
there was a grid of 1/8" cable across the room at fixture height, with cable clamps keeping
the fixtures from swinging. the cables were anchored to the walls of the building.
nothing will sway except the state budget deficit. it would take more than 1/8" gal wire
rope to keep it steady.
3/4" min conduit size
all conduit below 8' GRC, including above panels
2 hole conduit straps
compression fittings
then there were the structural requirements.....
a 70 LB mushroom fan took 4 x 8 cross bracing
between glue lams. grade 1 timber, with grading
stamp visible from floor.
http://i470.photobucket.com/albums/rr66/FulThrotl/1fc3aaa3.jpg?t=1317082052
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ron
Senior Member
- Location
- New York, 40.7514,-73.9925
This is the information I have.
http://www.usg.com/rc/technical-art...ixture-hanger-wire-requirements-en-SC2493.pdf
The International Building Code (IBC) details the positive attachment of light fixtures to suspended ceiling systems in Sections 1613.1 and 25.213 which references ASCE 7 13.5.6.2 which in turn references CISCA 0-2, 3-4:
IBC SECTION 1613 EARTHQUAKE LOADS
1613.1 Scope.
Every structure, and portion thereof, including nonstructural components
that are permanently attached to structures and their supports and attachments,
shall be designed and constructed to resist the effects of earthquake motions in
accordance with ASCE 7, excluding Chapter 14 and
Appendix 11A. The seismic design category for a structure is permitted to
be determined in accordance with Section 1613 or ASCE 7.
PEDRO ESCOVILLA
Senior Member
- Location
- south texas
I can remember when this was in the UBC, detailing requirements for wires supporting fixtures, wires attached to the building structure. It also think it may have been in the NEC back in the '80's. Now, I find , we have to go to the Accptance Criteria for Attachment Devices For recessed Lighting Fixtures (luminaires) In Suspended Ceiling Systems, an ICC ES report AC 184. Or to a ceiling system maunfacturers instructions. I can't understand for the life of me why this information gets chopped out of the code books. One has to maintain a prolific library of reference documents, and if like me, you are "out of the field" for a while, SURPRISE, you may not find it. some just hang thier hat on the weight of the fixture requirements. It needs to go back in the book (IMHO)
PEDRO ESCOVILLA
Senior Member
- Location
- south texas
Here's another argument for wires or support required on all troffers in suspended ceiling systems. A fire breaks out above a ceiling area, firefighters come in to put it out, axes beging pulling down ceiling grid and FIXTURES START SMACKING THESE GUYS ON THE HEAD., OR IN THE FACE. Yes, they have helmets on, but really, think about it. This is another reason for those supports, (IMHO), and I better get busy on a code change proposal, and quit my b@#$hing.
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