Additional Information on the World Trade Center Fire Alarm System

This post was originally published on The Fire Panel Forums on August 16, 2018.

Today, RSSAlarms sent me an interesting question pertaining to this topic. He asked me the following:

You did mention that the old Cerberus pyrotronics at the old WTC system had SS70 speaker strobes, however I have no idea what they look like and I wanted to ask you if you have any pictures or document of that particular device.

Finding a definitive answer to this was a bit more complicated that just a simple Google search, so here is what I discovered.

First off, it has now been over five years since I originally shared this post. If I could go back in time to then, I would have done a better job at providing references to my sources. Actually, I would have used actual sources for my info, and not just relied on some anonymous user’s comments from the Schumin Web Community, as I did:

During this time, speakers were located in all floor areas, and were spaced to insure intelligibility and audibility. In addition, strobes were located in all common areas that were area spaced and rated to ensure adequate illumination for notification of the hearing impaired. The speaker strobes were supposedly Cerberus Pyrotronics SS70-15/75, or a similar product (as speculated by a member of The Schumin Web Community several years ago).

Fortunately, I was able to find the page where I gleaned this information from, which is a 9/11 conspiracy forum that seems like it was attempting to find out if a company as sinister sounding as “Cerberus Pyrotronics” was “in” on the fact that 9/11 was an inside job. Needless to say, they didn’t uncover anything, but they did nicely preserve the post from The Schumin Web Community that I was referencing.

Q: I’ve got a long-time question: does anyone know what the alarms were in the World Trade Center? While watching a couple of documentaries, I’ve seen an RSS in there, and what looked like a Cerberus Pytrotronics voice panel, but that’s it…

A: Well, obviously what’s in the documentaries aren’t the real alarms (unless it’s actual footage of the buildings). Reading all the reports, I have the model #s of all the devices, but the trouble is the signals are hard to come by. For instance, the combination speaker/strobe units were Cerberus Pyrotronics SS70-15/75. I thought these would be MTL-style speaker/strobes, but last week, I came across an auction for an alarm w/ the exact same model #, and it turned out to be a rebranded Wheelock LSM speaker/strobe. SO, IDK whether they were rebranded Wheelock alarms or actual CP alarms.

But yes, the main panels were Cerberus Pyrotronics MXL-Vs located in the lobbies of the building they served. They monitored 5 remote panels, which monitored 8 “slave” panels which monitored “fire control cabinets” on each floor.

also see: http://wtc.nist.gov/pubs/NISTNCSTAR1-4CDraft.pdf

Now, this all seems like a pretty good answer, the SS70 alarms were just rebranded Wheelock speaker/strobes, but there’s no way to really verify it, and concrete verification is what I am looking for right now. So, I dug a bit deeper, and here is some evidence supporting that claim that the Cerberus Pyrotronics SS70-15/75 Speaker Strobes in the World Trade Center, were rebranded MTL-style speaker/strobes.

I guess the first thing I would actually want to do would be to verify the authenticity of these alarms being that particular model number. The link at the end of that post leads to the NIST report on the WTC fire alarm system. I believe that this document was the source for 95% of the material in my first post and is a very comprehensive review and description of the WTC’s systems. I would recommend checking it out, there’s some cool stuff in there. (Here’s a link to an archived version since it seemed like they moved the file to a different URL. On page 90 of that document, we get specific model numbers for what kind of notification appliances were being used.

The Siemens Pyrotronics devices used for audio notification included:
• Ceiling mounted round speakers, 70 V (SPK-9070)
• Wall mounted square speakers, 70 V (SPK-7070)
• Wall mounted speakers, 25/70 V (SPK-1070)
• Wall mounted speakers, 70 V, with 24 V 15/75 cd strobe (SS70-15/75)

However, this document just provides us with info about the notification appliances with audio capabilities. Based off of the wiring diagrams on pages 59-61, it seems like the system was designed to be using remote ceiling mount speakers and remote wall-mount strobes separately. Unfortunately, there’s no concrete evidence as to the exact type of strobe used for visual notification, or maybe someone can located the referenced “documentaries” that show an RSS as mentioned in the quote from The Schumin Web.

What I am really trying to nail down is what kind of alarm a Cerberus Pyrotronics SS70-15/75 is, so I will be getting to that….soon…

First, I would like to point out that this is what a Cerberus Pyrotronics SPK-9070 looks like:

That alarm, of course, is a re-branded Wheelock E90-W (or similar) speaker.

And I do realize that the screw holes on these speakers are different, but there are other Wheelock, white ceiling mount speakers that have the same four-hole configuration like the CP one. (This unit just happens to have a strobe on it, but you get the point)

The reason why I was going through all of that was just to show that the WTC was using rebranded Wheelock Notification Appliances. There is also evidence to show that Cerberus Pyrotronics did rebrand Wheelock LSM Speaker/Strobes. From our friend Ben Schumin, here’s a photo of such a device. Note the Cerberus Pyrotronics label at the bottom of the alarm.

The model number “SS70-15/75” is indicative of the numbering schema that Cerberus Pyrotronics used with rebranded Wheelock products that were being produced around the time that they would have been installed in the World Trade Center. Here is a Cerberus Pyrotronics HM-30 (“HornMini-30”)

Here’s a Cerberus Pyrotronics S75-STD (“Strobe”75-“SexuallyTransm….” oh….wait….”). Also, these very well could have been the type of strobe in the WTC, but that is just mostly speculation.

Lastly, from Dan’s collection, a Cerberus Pyrotronics MTS4-15/75. (“Multi-ToneStrobeFourWire-15/75”)

Based on this pattern, we can extrapolate that “SS70-15/75” is “SpeakerStrobe70(watts)-15/75(strobe candelas).”

I recognize that the design of the speaker/strobe could have varied from the example above. For example, maybe it had the vandal resistant grille or the non-ADA strobe, but I think you get the point, and I hope you are happy at the evidence presented and the conclusion drawn. These were likely the notification appliances in the World Trade Center.

Also, as a bonus, here’s a picture of a Cerberus Pyrotronics branded Gamewell Century pull station, which were allegedly the type used in the World Trade Center. I’m posting this for no reason other than to prove that this rebrand does exist, verifying my claim that I made in my original post these were the pull stations used in the system.

World Trade Center Fire Alarm System History

Category : Miscellaneous

In 2013, I had written a brief history of the fire alarm systems in the New York City World Trade Center. These were published on The Fire Panel Forums until a server crash necessitated me to move them to this website. Below is my original post in its entirety (or view an archived version here).

After doing a bit of research, I have pieced together the following descriptions of the two fire alarm systems that were installed in the World Trade Center from the time it opened to the September 11 Terrorist Attacks.

Please not that I am posting this history to show how fire alarm coverage worked in a campus as large as the World Trade Center, and am not trying to send the message that the fire alarm system in these buildings was more important than the 1993 bombings on the 9/11 attacks, or something like that.

In addition, I’m pretty sure that some of the pictures on here have been shared on this forum and some other ones before, so please excuse the redundancy.

With all that said, here it is:

Original Fire Alarm System (Prior to 1993 Bombings)

The pre-1993 fire alarm system encompassed WTC 1, WTC 2, WTC 4, and WTC 5, as well as the concourse and sub-grade levels.

The system consisted of American Multiplex Remote Monitoring Transponders, on every third floor, connected to the Digital Computer and Console in the Operations Control Center (OCC) on the B-! Sub-Grade Level. The Transponder monitored Pyrotronics CR-7 equipment connected to type DI-2, DI-3, DI-4A, and DI-7 smoke detectors (non-addressable), Pyrotronics System 3 panels, tenant proprietary systems, waterflow stitches, tamper switches, and control contacts.

Pyrotronics XL3 smoke detector systems, with addressable detectors were installed in the mechanical equipment rooms of WTC 1, as well as WTC 2, and were connected via a CXL Communication Devices to a console in the OCC.

Manual pull stations were wired to an existing Executone system which alarmed directly to NYFD.

The pull stations used in this system were break glass stations combined with a two-way intercom in one unit. The glass rod was broken by pushing a spring-loaded pushbutton. A protective shield helped to stop the flying glass. The speaker/microphone, located inside of the pull station, allowed conversation over the fire intercom system to the Police Security Room on level B1.

The pull stations were model C3002, manufactured by Executone, Inc., located in Long Island City, New York.

Many tenants during this time had their own smoke alarm systems. Since the designs of those systems were varied, their descriptions are beyond the scope of available documentation.

There were two types of speakers used in the WTC: the horn loudspeaker and the recessed ceiling speaker. Speakers were located in the corridors stairways, and in the core area of the ventilation ducts.

(I do apologize for the couple of images that are rotated incorrectly.)

Executone C3002 Pull Station in the World Trade Center (Pre-1993 Bombings)

Fire Alarm/Public Address Control Panel in the World Trade Center (Pre-1993 Bombings)

Pyrotronics Smoke Detector in the World Trade Center (Pre-1993 Bombings)

Duct Detector in the World Trade Center (Pre-1993 Bombings)

Duct Detector

Public Address Loudspeaker in the World Trade Center (Pre-1993 Bombings)

Fire Alarm System Components in the World Trade Center (Pre-1993 Bombings)

Fire Alarm/Public Address System Control Panel in the World Trade Center (Pre-1993 Bombings)

Waterflow Control in the World Trade Center (Pre-1993 Bombings)

Waterflow/Sprlinker Control in the World Trade Center (Pre-1993 Bombings)

Post 1993 Bombings System
The fire alarm systems in WTC 1 and WTC 2 were replaced following the 1993 World Trade Center bombings.

A Cerberus Pyrotronics MXL-V fire alarm system with emergency voice/alarm capabilities was chosen for the new system. The system supported a decentralized infrastructure that consisted of six independent fire alarm systems protecting WTC 1, WTC 2, WTC 4, WTC 5, Concourse Level and the Sub-Grade Levels. These four buildings had a master monitoring and control Network Command Center located at each building’s Fire Command Station which were located in the entrance lobby of each building. Multiple redundant Network Command Centers were installed. The installation of the system was divide into these three phases:

1. Phase one consisted of the system’s backbone, the master fire alarm panel, which was the Cerberus Pyrotronics MXL-V, Cerberus Pyrotronics MXL-VR remote transponder panels, and amplifier cabinets. This phase was completed sometime between 1995-1997.

2. Phase two consisted of transferring monitoring and control of existing fire alarm devices to the new system. Both the existing American Multiplex system and the MXL-V were operating concurrently during this time. New core area speakers, warden phones, and pull stations were connected to the new fire alarm system as well.This phase was also completed sometime between 1995-1997.

3. Throughout phase three, all existing fire detection devices were replaced, and the new speaker and strobe capabilities were expanded into all tenant and mechanical spaces. The existing American Multiplex system was to be disconnected and removed, but that had no occurred by the September 11 attacks. It was estimated the 25 % of the American Multiplex system was still in use at that time.

By 9/11, 85 % it was estimated that 85% of WTC 1 was completed, 80% of WTC 2 was completed, both WTC 4 and WTC 5 were 60 % completed, the concourse level was 100 % completed, the mechanical rooms were 40% completed, and the sub-grade and global fiber optic loop interconnecting all six systems were 0% completed.

Throughout the 12,000,000 ft2 WTC complexes, it was estimated that over 10,000 iniating devices (including smoke detectors, pull stations, water flow indicators, etc.), 30,000 notification appliances (speaker/strobes), and over 700,000 ft of conduit and 5 million feet of wire were installed.

During this time, speakers were located in all floor areas, and were spaced to insure intelligibility and audibility. In addition, strobes were located in all common areas that were area spaced and rated to ensure adequate illumination for notification of the hearing impaired. The speaker strobes were supposedly Cerberus Pyrotronics SS70-15/75, or a similar product (as speculated by a member of The Schumin Web Community several years ago).

"This is a photgraph of the One World Trade Center Fire Command Station (310A). Seated is Lloyd Thompson, Fire Safety Director and Standing John Drucker Jr., Siemens Fire Safety Project Manager. The equipment shown is the WTC Fire Alarm and Evacuation System. I spent 8 1/2 years at the WTC working with the Port Authority of NY & NJ to restore, engineer and upgrade the Base Building Fire Alarm and Evacuation System at the World Trade Center. God Bless those who perished that fateful day especially my dear friend James Barbella. Sincerely, John Drucker jr."

Cerberus Pyrotronics MXL System

A representation of the Cerberus Pyrotronics pull stations in the WTC fire alarm system.