Support Requirements for suspended devices

[DM2-Inc]

We're designing a fire alarm system for a truck loading bay. Over each bay, the customer want's a fire alarm strobe light. Because the roof structure is so high, the strobe lights will need to be suspended some distance. Because the area is classified as Class I, Div 2, the conduit will be rigid and a junction box, with seal, will be used to make the wiring connections. The seal will installed ahead of the junction box such that the junction box is between the seal and the strobe (less than 18"). The seal, junction box, breather/drain, and strobe have a total weight of less than 10 lbs.

While I'm sure the electrician knows what the requirement is, I need to put a detail together that defines the mounting requirements.

Where can I find references in the NEC that tells me how far I can suspend this seal, junction box, breather/drain, and strobe, before it needs to be supported by something.

 

[don_resqcapt19]

I don't think there is a specific rule in the code for this application. I would treat it like a pendant light fixture and require compliance with 501.130(B)(3).

 

[hurk27]

Are you sure the area that high is a C1D2 area? in most cases it stops at a certain hight?

 

[DM2-Inc]

I would agree that normally this high above the ground wouldn't be classified, especially considering it's open on all sides. Unfortunately the clients Engineer has directed to follow Class I, Div 2 installation requirements. As I'm an ME and not a EE, I'm not going to challenge him/her.

While Don referenced Article 501.130(B)(3), I was originally thinking that the support requirement wouldn't be any different than any other fixture suspended in this mannor, however after giving it some thought, I'm guessing the code writers have this requirement to insure that any movement doesn't compromise the threaded connections.

I would however be interested to know where the reference would be for a non-hazardous location installation similar to what I had described?

 

[hurk27]

(2002) don't have 05 or 08 on here yet.
314.42 is about as close as I can find in the "2002"

And 725.61(D)(1)


and this is for above classified areas

511.7 Wiring and Equipment Installed Above Class I Locations.
(A) Wiring in Spaces Above Class I Locations.
(1) Fixed Wiring Above Class I Locations. All fixed wiring above Class I locations shall be in metal raceways, rigid nonmetallic conduit, electrical nonmetallic tubing, flexible metal conduit, liquidtight flexible metal conduit, or liquidtight flexible nonmetallic conduit or shall be Type MC, MI, manufactured wiring systems, or PLTC cable in accordance with Article 725, or Type TC cable or Type ITC cable in accordance with Article 727. Cellular metal floor raceways or cellular concrete floor raceways shall be permitted to be used only for supplying ceiling outlets or extensions to the area below the floor, but such raceways shall have no connections leading into or through any Class I location above the floor.
(2) Pendant. For pendants, flexible cord suitable for the type of service and listed for hard usage shall be used.

Not sure if this applies or if it is even in the "2008"

 

[gadfly56]

Are you using an XP strobe appliance? If it's listed for ceiling mounting, it can be as high as 30' AFF. Is this enough to get you to a firm structural member to which you can secure the appliance? See http://www.cooperwheelock.com/mediacenter/Specs/XB4.pdf for an example. (For some reason HTML is turned off and I can't get it back on). This puppy puts out 355 cd, enough to more than light up a 50' x 50' area from 30' up.

 

[DM2-Inc]

Be careful about the Candela rating of the device. The 355 is without a lens. If you take a look at the multiplier the best it can do is 266.25 with a yellow lens.

We've been using MEDC products since 2001 and it appears since the acquisition by Cooper, they've finally got the right listing. Previously they used CSA and the devices weren't listed for fire. A quick look at the listing and I see they're not used for fire.

MEDC is good for harsh locations, but we use the Federal Signal 224XST version as it's delivery is shorter and they're less expensive, by about $100.00.