Code Basis for Protecting Another Zone's Main?

7/1/2026

Here's an odd one. I have a single comment on a remodel project to protect a new feed main protecting an adjacent system. The basis is that, in the event that the system that the feed main is traveling through is down for maintenance, the main will be unprotected during a fire event. I have dealt with pilot sprinklers on exterior mains but not interior mains.

Is there a basis to protect an adjacent zone's main in the event it's down?

Anyone else coming across this scenario?

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6 Comments

Dan Wilder

7/1/2026 08:19:50 am

This would be a first within a fully sprinklered building for a comment like this. I have had a similar request for mains passing through unsprinklered areas of a building where the AHJ wanted a 2-hour rating or sprinkler protection above the main , similar to the pilot sprinkler installation you reference.

Was there a code referenced? What is your adopted Building/Fire Code for this project?

Josh Johnson

7/1/2026 10:49:33 am

No code section was provided in determining the comment -correction. We are using California Fire Code 2022 and the district has adopted NFPA-13 2025. We've done 20+ large warehouse projects over the years with this reviewer and have never come across this. I'm just going to have to keep circling back until I get a code section qualifying the request.

Cordell Beache

7/1/2026 08:21:12 am

It is common for the feed main serving one sprinkler system to pass through another fire area or zone before reaching the area it supplies. This condition is frequently encountered in warehouses with multiple sprinkler systems that are supplied from a common riser location.

In these arrangements, feed mains may traverse one or more adjacent zones without supplying sprinklers within those zones. Current requirements do not generally require these feed mains to be provided with additional fire protection solely because they pass through another zone, provided the installation otherwise complies with the applicable provisions of the governing standard.

RayJ link

7/1/2026 08:32:06 am

What about a fire watch while that main is down?

Glenn Berger

7/1/2026 08:36:54 am

Is the comment asking for a dual supply to the sprinkler system?

This does occur in larger (sometimes multi-tenant) manufacturing / industrial facilities where multiple sprinkler risers are clustered together.

I recently did a project where this happened. Sprinkler risers were grouped together in several locations, with a single underground feed to each group, and then redundantly supplied with a bulk main from the other side of the complex.

Jack G

7/2/2026 09:27:40 am

Only if it’s passing thru an area that has no sprinkler protection.
The codes will tell you 2 hr.
I ve used sprinklers for this and AHJ s usually accept them.

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Code Basis for Protecting Another Zone's Main?

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