Some end users will say they require a "UL Listed" product. It may be that they don't understand that the codes (i.e. building, NFPA, etc) do not require equipment to be "UL" listed but rather NRTL (Nationally Recognized Testing Laboratory).
Many codes will have statements to the affect "...acceptable to the Authority having jurisdiction..." (AHJ) and some will assume that when it comes fire protection the local fire marshal is the AHJ. The AHJ will depend on what the variance is. For example, while the local fire marshal may allow something that's on NRTL Listed to be installed, OSHA will eventually supersede him/her.
With regard to your horns FM is NRTL approved to test and certify your horns to both UL 1203 and FM 3615, but before I go into that, you need to understand the paper trail law, so...
OSHA provides the minimum requirements for fire protection under 29 CFR 1910.155 "Subpart L Fire protection". Section 1910.155(c)(3) states that equipment is "...approved..." based on one of three options:
a. The equipment is "...determined to be safe by a nationally recognized testing laboratory; or;"
b. If the equipment is of a nature "...which no nationally recognized testing laboratory accepts, certifies, lists, labels, or determines to be safe..." it may be used if "...inspected or tested by another federal agency and found to be in compliance with..." NFPA 72, or;.
c. If the equipment is "...custom made...for use by the manufacture..." and testing data is made "...available for inspection to the Assistant Secretary"
- Link to above reference: (see http://www.access.gpo.gov/nara/cfr/waisidx_08/29cfr1910_08.html
and than scroll down to 1910.155)
You may be asking "...who defines a NRTL?" Well, OSHA does under 29 CFR 1910.7 which defines a NRTL as:
"(b) Laboratory requirements. The term nationally recognized testing laboratory (NRTL) means an organization which is recognized by OSHA in accordance with appendix A..."
(go back to the previous web page and find 1910.7)
So next your probably asking "...who is an NRTL?". Well to find the answer to this question you need to go to OSHA's NRTL web site at: http://www.osha.gov/dts/otpca/nrtl
Here you'll see a number of testing laboratories including UL and FM. Now not every lab is qualified to test devices for Class 1, Div 1 locations. But as you mentioned, the UL standard your looking to have your equipment tested to is UL 1203.
To find out if FM is recognized by OSHA to test equipment to this standard, click on the FM link (http://www.osha.gov/dts/otpca/nrtl/fm.html
If you scroll down the page, you'll see "UL 1203" as one of the standards OSHA has recognized FM as being qualified to test to. Scroll down further and you'll see "FM 3515" as being a NRTL test standard.
The real question is whether or not the application of your horn is suitable for Class I, Division 1 areas, based on the "FM 3615" test. To find that out you should go to the "UL White Book" (http://www.ul.com/global/eng/documents/offerings/perspectives/regulators/2008_WhiteBook.pdf
) and look on page 410 of the book. Here you'll find the cross reference to NFPA 70, Article 500 through 506. This section is a cross reference to "UL Category Codes".
Equipment (i.e. your horn) falls under section III, and I suspect your horns fall under 501.150(A). According the page 454 of the white book, you need to be looking at the following UL Category Codes:
- UGKZ (Page 324) <--(Hint...Audible-signal Appliances for Use in Hazardous Locations)
- UGYX (Page 324)
- UHMV (Page 325)
- UIAZ (Page 325)
- UIOR (Page 325)
- UIPV (Page 325)
- UIRV (Page 326)
- UJFT (Page 326)
- UJPX (Page 326)
- UJQO (Page 326)
- UJTK (Page 328)
- UXWC (Page 328)
- WZAT (Page 357)
If you took the hint and went to page 324, you'd find that UGYX references Category Code AAIZ (Equipment for Use In And Relating to Class I, II, and III, Division 1 and 2 Hazardous Locations), however it isn't until page 46 that you'll see a reference to UL 1203.
Now...understand that the White Book only cross references the NFPA 70 standard to UL standards, not FM Standards.
You'll now need to review the the FM standard and see if it's similar.
You should also get a letter in writing from you contact at FM stating that the FM 3615, addresses devices intended for use under NFPA 70, section 501.150(A)
For information on how to use the UL White book, you can take an online course at: http://www.uluniversity.us/catalog/display.resource.aspx?resourceid=194559
, You'll have to register online with UL, but the course is a flash animation and is free, so it couldn't hurt.