Firestopping by the Numbers: Step by Step For Cable Installers

  1. You must know the hourly rating of the barrier. (5/8″ fire rated gypsum is rated for 1/2 hr. per sheet / Cement Cinder Blocks are rated at 2 hrs.)
  2. Select a UL tested product system with a UL Listing that matches or exceeds the barrier. Pay attention to cable loads and fill procedure for the product system you choose.
  3. Go to the Cable Load Chart link for the product system you chose. Select the proper size Sleeve, based on the % cable fill load permitted in the UL listing.
  4. Seek pre-approval from the Authority Having Jurisdiction (AHJ Inspector). Remember, it is approved if the Inspector says it is!
  5. When installing the System, be sure not to exceed the listing limitations. Read the listing.
  6. After installation, fill out the label and take a picture to document the System for future reference.

If you follow the steps listed above, you will guarantee AHJ acceptance.

Split Sleeve Assembly Instructions

Split Sleeve Firestop System

Determine cable violation in firewall (how many violations), angle of entry or exit. Inspect violation to determine the proper Split Sleeve System size (1″, 2″, 4″ inside diameters). Up to 48% of the aggregate cross-sectional area of the Sleeve may be filled with cables in walls and floors rated up to 2 hours; 34% cable load for 4 hour ratings. See the Load Chart and Installation Pictorial.

‘Clean-up’ the firewall penetration (both sides of wall) ensuring not to nick the cable jacket(s). Use a slotted coupling to mark Sleeves hole size. Work the bottom half of the Split Sleeve under the cables as you insert it into the wall penetration. Support the cable(s) as the upper half of split sleeve is inserted through the firewall. Install top half, maintaining sleeve polarity. Look for machine or paint marks on end of the Split Sleeve halves to insure the halves are installed as machined.

Work cables through the slot of the 1st washer, work the washer over the sleeve halves and against the wall. (If your hole is not the size of the sleeve, apply a 3/8 bead of firestop caulk behind the first washer on each side of the wall.) Install the 2nd square washer for the first side and invert the slot so the slots in the washers are 180 degrees from each other. Work the cables through the slot in the first coupling and begin to screw it down the sleeve until equal lengths protrude on both sides wall.

Repeat the above procedure for the other side of the Sleeve system. Tighten the slotted couplings only enough to seat the square washers. Do not over- or under-tighten the slotted couplings. HAND TIGHTEN ONLY.

Install a minimum 1-inch thickness of the supplied UNIQUE Intumescent Firestop Putty in both ends of the Sleeve System. See our UL Systems documentation for sealing Systems up to 4 hours. UNIQUE Intumescent Putty is supplied with the system.

Install the split bushing if there is a chance that more cables will be pulled in the future.

Be sure to fill out and adhere the Documentation Label as close as possible to the Sleeve System. Also, if you are installing several of these Sleeves, be sure to alphanumerically I. D. the walls. Use an indelible marker. Take a picture of your installed Sleeve System. You may need it in the future. Always refer to the UL document pertaining to your application for details and limitations!

Split Sleeve Installation Pictorial

Split Sleeve Firestop System

System contents: (2) 12 inch long threaded 1/2 sleeves, (4) slotted washers, (2) slotted couplings, (2) split bushings, 2 documentation/warning labels, and a package of UNIQUE Intumescent Putty. The zip ties are for the split bushings.
A common penetration violation in a sheet rock firewall. A Sleeve will control and direct the expansion of the fire-rated intumescent putty. Without a sleeve, this penetration may fail to restore the hourly rating of this wall.
Clean-up the firewall penetration (both sides of wall) ensuring not to nick the cable jacket(s). Use one of the washers as your guide.
Use one of the SSS halves to protect your cables. After you clean up the hole, slide the bottom half of the threaded sleeve under the cables. Take care to protect your cables. Look for the machine holes near the ends of the sleeve halves to maintain polarity.
Slide the top half over the cables, maintaining sleeve polarity, until both halves protrude evenly. Position the sleeve with the seams at 9 and 3 o’clock.
Work the cables through the slot in the first washer and work the washer down the sleeve, against the wall. The first washers slot should be positioned at the 6 o’clock position. NOTE that the inside washers for both sides does not have printed information. The SSS will need a bead of caulk if the holes in the wall are not exactly the OD (outside diameter) of the SSS to be installed.
Install the second slotted washer, inverting the slots 180 degrees from each other (12 o’clock). Make sure UL label is facing out! Position sleeve protrusion equally.
Work the cables through the slotted coupling and screw it down against the washers. HAND TIGHTEN ONLY.
Repeat this procedure on the other side of the wall. HAND TIGHTEN ONLY.
Install a minimum 1-inch thickness of the supplied UNIQUE Intumescent Firestop Putty in both ends of the Sleeve System. See our UL Systems documentation for sealing Systems up to 4 hours. UNIQUE Intumescent Putty is supplied with the system.
Install the “split bushings”, taking care not to open the bushing any more than is needed to get the cables in. There are a pair of zip ties for securing the split bushings in place after installation.
Install the documentation labels on both sides. We advise you to ID (indelible marker) and take a picture of your installed system for an added bonus – protection of your workmanship.

Firestop Certification: Customer Testimonials

From a construction coordinator at Time Warner Cable:

time warner cableThank you!

I watched the firestopping video and looked at Fire Stopping By the Numbers and it helped a lot. I thought this was a very informative site, loaded with useful information. Until I got a Construction Coordinator position here at Time Warner Cable I didn’t realize there was so much to know about fire stopping techniques. — Doug G.




Robert Strickland

6 reviews

3 weeks ago-

When budgeting a job, buying materials is a game of inches. Unique products give me an installable product in a neat package. No costly design development and implementation. Just order the device install and proceed.


Mike R

3 reviews

9 months ago

I’ve been using these fire sleeves for years. They are easy to install and easy to teach technicians how to install. Not only that they look good and customers and GC’s love them. Mike Sr. is great to work with and the turn around time to get these is fantastic. I highly recommend!


Chris Herrington

2 reviews

9 months ago

Incredible training, and support on the proper way to install fire stop products. Great products too!!



Installation Slideshows for Unique Fire Stop Products

We’re very pleased to announce the addition of our Unique Fire Stop Products SlideShare channel where we share installation pictorials for our products and tips and how-to’s designed to make the life of the cable fire stop installer easier and worry-free.

UPDATED February 1, 2016 to include the Unique Threaded Sleeve Fire Stop System.

UPDATED January 11, 2016 to include the Unique Smooth Firestop Sleeve System.

We’re kicking things off with one of our most popular products, the Unique Split Sleeve Firestop System:

This month’s tip is around future-proofing cable fire stops in new buildings, a common concern for architects, designers and engineers. Customers can rely on our made-to-order Future Proof Plates, a tool for planning, centralizing, installing and maintaining firewall penetrations made by cable installers for the life of a new building.

The Art of Pleasing the AHJ (Authority Having Jurisdiction) When Firestopping

With over 40 years in the cabling business and 20+ years as a firestop manufacturer I am confident I can help you if you are routing cables through fire-rated barriers. Here is what you need to know.

Who is an AHJ Inspector?

Inspectors are always the same in that they all carry the burden of being the individual who must approve or disapprove someone’s work or product. All AHJ’s (Authority Having Jurisdiction) want themselves and their organizations to be protected from liability, so naturally it is important to identify who the AHJ is. The American National Electrical Code states that the AHJ is the local, state or federal official designated and responsible for approving equipment, installation or procedure. In essence, the AHJ assumes some liability when he/she makes a decision.

Today’s lawsuit-happy environment requires the AHJ to proceed with more caution than in the past, which means that the AHJ may even be someone other than the typical inspectors listed above. The definition in the NEC code clearly states that insurance inspectors or risk assessment agents are AHJ’s. A building owner or his designated agent may assume the role of the AHJ; in the building industry, an OSHA inspector could be the AHJ. If you are a manufacturer, an Underwriters Laboratories follow-up inspector is the AHJ. That is certainly a lot of authority to contend with!

What Do AHJ Inspectors Want?

Even with all that we are faced with in dealing with the AHJ, inspectors are easy. They are all consistent as far as what they are looking for when cables penetrate fire rated barriers. Why not give them what they want? Develop a Standard Operating Procedure for dealing with any AHJ with reference to firestopping telecommunications cabling. Most Inspectors are surprised when a telecom installer even makes an effort to properly firestop cables much less have a plan in place to do it professionally!

Always Consider the AHJ

You must bid the firestop procedure you select, so do it as an addendum if your competitors will not bid it. Just because firestopping is not in the scope of work, it does not mean that it does not have to be done. If compensated adequately for your firestop procedure, the beneficiary is the customer who is in the structure if it ever catches fire. The project manager or primary contractor may inadvertently be placing the burden and in due time, the blame, squarely on you.

Don’t fall for it. If firestopping is not in the bid or scope of work, make an issue of it and go on record as seeking to do it properly. The same guy who told you it was OK to just stick a little red group in the hole is the very individual who will point a finger at you if there is a fire.

[Read more…]

The Automotive Firewall. How to Protect Race Car Drivers.

UNIQUE Extreme Competition Automotive FirestopperHenry Ford saw the value of protecting his equipment and protecting his driver when he invented the first automotive firewall for cars. It was born of necessity. There was no way he could sell cars if the motor should catch fire and the driver or passenger was burned. Ford also envisioned the ability to drive the car without smoke, fumes and gases overwhelming the driver.

When the first “car firewall” was invented, it was simple, it was clean and it worked. It worked so well that other manufacturers of cars, trucks, and buses adopted the idea and the “automotive firewall” became a household name. This was almost 50 years before there were structural building or computer firewalls!

The Automotive Firewall- A Case Study

The following questions were asked of 100 mechanics as part of a case study:

  • What is the metal plate called that separates the driver from the engine compartment? All 100 mechanics called the metal plate a “firewall.” A random survey of 100 middle aged men were asked the same question. Ninety five percent called it a firewall and 5 % did not know the name but mentioned that it was supposed to stop a fire.
  • When the participants in the survey were asked if they were convinced the automotive firewall would protect them in case of an engine fire in a modern vehicle, the response was as follows: 100% of the mechanics (some took a pause before answering) thought that it might protect them for a few seconds in a raging engine fire but all agreed that any engine fire will be nasty. The wires cables and hoses will be the first spots to give way to fire. As they burn, they will pump toxic gas and smoke in the driver’s compartment through openings created when the plastic, rubber or tar like substance becomes fully involved and melt. The mechanics also noted openings around the steering shaft and shifter openings will fail to stop an engine fire and contain it to the engine compartment as Henry Ford intended.  Today’s cars are inundated with penetrations made by speaker wires, telemetry equipment and video cables. All fuel for a fire. But wait there is MORE.

[Read more…]

Fire Stop Installer Tips: Do’s and Don’ts When Firestopping

By Mike Tobias, Unique Fire Stop Products

Why is it Important to Do Firestopping Correctly?

Firestopping is such a hot issue now because cabling professionals have not been doing a very good job of it. Public safety officials, fire marshals, and building inspectors want us to respect the firewall, which is designed to save lives and property in the event of a fire. In fact, any AHJ (Authority Having Jurisdiction) will require a cable installer to restore the firewall to it’s previous rating before they approve the job. So it’s very important that firestopping is done correctly. However, there is some confusion as to how to properly firestop a cabling installation.

Firestopping to Code

The National Electrical Code (NEC) requires that metallic conduit be installed in vertical penetrations of fire barriers. The conduit sleeve has a fill capacity, usually under 50%, and the resulting void must be filled with fire-dam caulk or putty. There should also be backing for the intumescent material to expand against. (Intumescent material expands in the presence of heat.) Installing cables in a core-drilled floor without the benefit of a metallic mechanical sleeve is a violation of the fire code.

The NEC is less straightforward in dealing with horizontal penetrations of fire barriers: It stops short of calling for metallic conduit, but instead, specifies an ‘approved system’. This can create confusion among low-voltage cabling installers, who may think that a tube of fire-dam caulk is, in itself, an approved system. This is not the case. Approved systems consist of installation guidelines as well as materials, and such comprehensive assembly instructions are rarely found on tubes of caulk.

Firestopping tips:

Here are some practical firestop installer tips to consider when you are faced with firestopping a cabling installation:

  • Does your company have a standard operating procedure for accomplishing this task? If not, one should be established. If you have one, it should be reviewed periodically.
  • Firestopping procedures should explicitly follow manufacturers’ instructions for products such as caulks and putties. There are inherent limitations not found on the package. AHJ Inspectors know these limitations. Don’t exceed them!
  • Before beginning a job, contact the local building inspector and fire marshall to make sure you are complying with the fire codes in your area. Better yet, get pre-approval for your system using our AHJ Pre-approval form found here and on many of our product pages.
  • Use a Metallic Sleeve System  for both vertical and horizontal penetrations of fire barriers. They are the most durable method for firestopping through penetrations.
  • Whatever firestopping method you employ, ensure that all materials and assemblies are approved by a nationally recognized testing facility, such as UL.
  • At the penetration, use indelible ink to record your company name, the date, and the number of cables penetrating the fire barrier. Purchase a disposable camera and take pictures of your penetration next to the documentation. This will protect you if other companies open your firestop assembly and exceed its fill capacity or otherwise violate the fire code.
  • Do not run new cables through existing violations of fire barriers. Some building inspectors will then hold you responsible for all cables in violation of the fire code.
  • Do not caulk or ‘mud up’ around your cables if the fill cavity exceeds the recommended limits. Minimum depth thickness is affected by the space to be packed.
  • Do not exceed the fill capacity of a sleeve. Most caulks and putties are intumescent and will expand to seal the sleeve when exposed to heat.
  • Remember to drill oversized holes for core-drilled conduit. For example, for a 4-inch sleeve, you need a 4 ½-inch hole.
  • Do not use regular insulation in place of mineral wool batt insulation for packing.

At Unique Fire Stop Products, we pride ourselves on providing the best quality firestop products, prices, installer training, and customer service available. Contact us if you have questions about any of our systems.

Fire Stopping Existing Cables: Split Sleeve Advantages


Building codes are a requirement for the simple reasons of safety and insurance against improper building techniques on all commercial buildings. One of the most serious code violations occurs when a fire wall is penetrated and not sealed properly. In an inspection that reveals cable penetrations that violate a rated fire wall, the inspector may require the cables be removed, the wall sleeved with a conduit and re-installation of the cables.

Retrofitting low voltage violations have left a lot to be desired with “approved” or “tested” systems. Most systems deal only with point of entry and exit. Simply filling in around installed cables with caulk or putty will not satisfy most inspectors. If the cables in question are running equipment that can’t be shut down (like computer systems in hospitals or factories, security cameras or other important systems) you have a problem.

The days of getting off with a slap on the wrist are over — as well as the old tradition of “mudding” around your violation. In today’s commercial building environment you will need to prepare to meet and make happy the fire marshall, the local building inspector, as well as the county inspectors (known collectively as the Authority Having Jurisdiction).

Through penetrations should be:

  1. Functional
  2. Easily installed
  3. Re-enterable
  4. Reasonably priced


A Split Sleeve Fire Stop made by Unique FireStop Products.


The system uses a 12 inch section of rigid conduit that is threaded on the outside and split down its axis. The two halves act as an outer casing around the cables. A pair of slotted washers are worked over the cables, over the assembled sleeve and against the fire wall with the slots 180 degrees from each other. A slotted coupler (nut) is provided for each side to keep the two threaded halves together and to secure the washers to the wall.

After the sleeve is installed around the cables, stuff the end with wool batt insulation and finish the job with a minimum of one inch of Fire Stop Putty, applied in front of the insulation to form a seal flush with the end of the sleeve. Additional cables can be added later.

Split Sleeve Systems are available in one inch for a few cables; two and four inch systems are for small and medium size cable bundles. A bulkhead plate has been developed for larger holes and can be ordered in any size or configuration.

For visual, step-by-step instructions, see our Installation Pictorial for the Unique Split Sleeve Fire Stop System.

Firestopping New Cable Installations: Through Penetration of Fire Walls