Understanding UL Nomenclature for Firestop-Through Penetrations: Part 2

So, now that you understand the letters a little (see here for review), let’s get into the numbers. You are going to have to just memorize these. The 1000 series details are for metal pipes and conduits. So, with the list below and the information in the previous blog post you now understand how someone could easily tell you that a duct through a gypsum wall would be a WL 7000 series detail (mentioned from a previous blog post).

  • 1xxx- metal pipes
  • 2xxx- plastic pipes
  • 3xxx- cables
  • 4xxx- cable trays
  • 5xxx- insulated pipe
  • 6xxx- electrical busway
  • 7xxx- mechanical
  • 8xxx- combinations

Chew on that list for a while. Maybe pick two or three of the applications you deal with most of the time and focus on that your first week. Add a few other numbers to your repertoire the next week. You might start with 1000, 5000 and 7000, then add in 3000, 4000 and 8000, then tackle 2000 and 6000 in the end (just don’t forget them).


There is a little more information that might be helpful once you have digested the list above. 2000 series will be plastic pipes but it will also be where you will find the details for innerduct or plastic conduits. (Side note: if you have innerduct on your project please email me because there is a strong chance it is being done wrong. I plan to blog on this later, but you need my help now if you have innerduct being firestopped).

The 7000 series details are going to be where you will find details for ductwork but it is also where you will find the detail for miscellaneous metal applications such as threaded rod or uni-strut through a rated assembly. If you are inspecting a firestopped unistrut please check inside the center of the strut to be sure the installer has the proper firestop placement. This is difficult to see, which makes it easy to miss. Another fun one is the seismic bracing for sprinkler pipes. Did you know this needs to be firestopped if it penetrates a rated assembly? It not only needs to be firestopped around the pipe where it penetrates the wall but also INSIDE the pipe because it creates a chimney through which smoke and toxic gas can spread. UL listed details change on a regular basis, and they vary from one manufacturer to the next so it is likely that this will require an EJ (Engineering Judgment). Please review the International Firestop Council’s Guidelines for Evaluating EJ’s at this link. They are an excellent resource for other firestop related information as well.

We have one last thing to cover before we are done talking about the number sequence in the UL nomenclature. We have not yet discussed the 8000 series details. If you have an application that has a copper pipe and an insulated pipe, you can’t use the 1000 series detail because it doesn’t deal with the insulated pipe, which is considered combustible in a fire scenario. You can’t use the 5000 series details because of the bare pipe. You have a lot of information to take in. Now let’s go on to Part 3 and we will go over the 8000 series details!

If you have innerduct on your project, please email me because there is a high chance it is not being installed properly. If it is being done right would love to hear about it. I will give you a high-five, a pat on the back and maybe even buy you a beer if I run into you in the local pub.

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