Know when to say when: friends don’t let friends overfill sleeves

Recently I was at a cocktail party making some new connections when someone asked me the good old question, “So, what do you do?”

As a sales rep in the firestop industry, whenever I get this question, I have to quickly make a decision on just how much I’m prepared to share about my everyday life, or for that matter, how much do I think the person asking really wants to hear. I always ponder how much easier it would be if I were a lawyer, a doctor, or a mechanic for that matter. I know that whenever someone tells me they are a lawyer, doctor or mechanic, I automatically think of a very simple follow-up question like: ‘what type of law?’, ‘what type of medicine?’, or ‘what type of vehicles do you work on?’ Instead I’ll get what seems like an obligatory blank stare, followed by a question like ‘what in the world is firestop?’

I have found that most people have no idea what firestop is, so I always ask a qualifying ‘are you sure you want to know?’ then I start from the beginning… owners… architects… curtain wall… fire-rated assemblies… passive fire protection… compartmentalization… penetrants… annular space… intumescent… and so on. If my audience’s eyes haven’t completely rolled into the back of their heads’ at that point, they will generally start to understand what I’m talking. About this time I tie the overall concept of firestopping into a topic that they can relate to, low-voltage cabling. Anyone who owns a home has had some experience with a contractor coming into their house to run a new cable, and the subsequent hole created and left behind by their phone, cable or internet company. I’ll ask them to consider a high-rise condominium with multiple families and thousands of cables or brokerage business in office building and the cables feeding individual work stations, or educational facilities connecting to ever-changing technology. I grabbed my phone to pull open a BICSI-accredited PowerPoint presentation that I typically give to illustrate potential firestop/cabling issues; one gentleman politely excused himself and two others started their own side conversation.

I thought I was in the clear, when Bob, a P.E. from Princeton, or was it Yale, wanted to know more. Hopefully I can get through the barrage of technical questions I’m about to get I thought to myself. But instead I got this softball, “So, what happens when new tenants and thus new cabling needs to be run in an existing building?”

Great question Bob!

Moves, adds and changes in low voltage cabling is the biggest challenge in maintaining code compliance and more importantly the life safety of a figure 1building. Datacom cabling is an example of penetrants that will often require change or removal or replacement over the lifecycle of occupying tenant. As such, we need retrofittable sealing products such as putty (see right) that can be removed and reinstalled as necessary.

The below diagram shows the typical life-cycle of low voltage cables installed in a traditional firestop sleeve where cables are added over time and firestopping is removed, eventually leaving us with all cables.figure 2.png

Deployment of new technologies and the size and scope of the Local Area Network ( LAN) are growing exponentially on a daily basis. There are a massive number of communications cables finding their way into concealed overhead and underfloor spaces of open-plan offices, health care facilities and educational institutions throughout the world, posing a significant burden to firestopping systems on a daily basis. There are 2 key challenges to maintaining code-compliant, firestopped sleeves:



The first challenge can easily be solved with by creating a Standard Operating Procedure (SOP) to ensure that a retrofittable seal is used and replaced. Very few buildings, outside of healthcare facilities, have inspections after the building is open. This means that over time firestop seals may be compromised, or removed and not reinstalled properly according to code leaving a potentially devastating life-safety issue. An SOP helps to establish guidelines and parameters for how to properly install a tested and listed UL® System and how to maintain that opening moving forward, along with specifications including products and sealing methods to be used. For best practices, consider implementing some sort of barrier management program, they are available in printed (cBMP) or digital (eBMP) versions.


The biggest safety concern is allowing cables to totally displace the firestop materials and/or exceed the maximum allowable percentage of cable fill. The biggest question is always what is the maximum % of cable fill allowed in a sleeve?

Often time, contractors who install firestop systems talk about the 35-40% rule of thumb, believing that the National Electrical Code (NEC) calls out the maximum allowable cable fill in a sleeved opening. This is a common misconception that artificially restricts the
cable fill of sleeved openings  in fire-rated and non-fire-rated construction alike. The NEC, although often cited generically as restricting sleeve fills to a maximum of 40%, in reality places no restrictions on maximum cable fill in sleeves. The cable fill requirements of the NEC are applicable only to conduit and tubing systems and do not apply to short sections of pathway used to protect cabling from physical harm a.k.a. sleeves, see NEC(NFPA 70) Chapter 9, Table 1 Note 2. Furthermore, the NEC specifically states that low voltage cabling is exempt from pathway fill requirements, see Articles 770.110, 800.110 & 820.110.

Firestop systems evaluated to the parameters of ASTM E814/UL 1479 are the actual limiting factor in regards to cable fill in sleeves passing through fire-rated construction (such as the 46% fill called out in UL® system WL3133: aggregate cross-sectional area of cables in sleeve to be max 46 percent of the cross-sectional area of the sleeve. Cables to be tightly bundled.). Cramming that last cable into a tightly packed sleeve can push it beyond what the original firestop system was designed to accommodate making the installation non-compliant. When sleeve fills are exceeded, more robust and expensive solutions are required such as firestop collars. These remediation efforts also make existing sleeves static and require a new sleeve or pathway to be installed to accommodate future work.

Taking steps to prevent sleeve overfill in traditional methods is possible, but are not fool proof and result in increased administrative and inspection/maintenance costs and documentation. Along with being cognizant of % of sleeve fill, keeping enough fire stopping material on site is recommended, as is the labeling of sleeves that are close to or have reached their maximum capacity.

So Bob, as you can see with the growing number of networks and cabling needs has come heightened awareness among contractors, designers, and installers that their firestopping efforts may be better served by installing high-fire-performance cables through zero-maintenance fire-rated pathways with factory-metered and installed self-adjusting firestopping preinstalled. Zero-maintenance fire-rated pathways completely eliminate the guesswork and need to keep firestopping materials around after construction has been completed; potentially saving lives and property damage with “built in” security. When it comes to traditional firestopping methods, you never stop paying. You pay to put it in and every time you make cable changes, you do it again. The more changes you make, the more it costs you both in time and money… Not to mention disruption!

With the EZ-Path® System, firestopping is a one-time event! No sealant, putty, or foam pads to remove and replace. Nothing to adjust. Nothing to loosen and re-tighten!


Click on the above graphic to see EZ Path in action!




About zalepka

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