Fire Pump Service requirements

[jahilliard]

We need to provide service to 2 new Fire Pumps for an existing Wal-Mart. The 480V transformer is directly adjacent to the building and the Sprinkler Room is approx 80' away on the other side of the exterior wall. Is it NEC compliant to run conduit and conductors underground from the transformer to the exterior wall, travel along the outside of the building along the exterior wall and punch through the wall directly into the sprinkler room? The main question would that be considered "outside the building" therefore not requiring the Fire rating, Concrete encasement etc.? This is completely separate from any other services currently coming to the building and will not have any means of disconnect ahead of the Pump Controllers. The plan detail describes the installation in this way but I am not sure the conduit traveling along the exterior of the wall is considered "outside the building".

 

[Boingo1972]

We need to provide service to 2 new Fire Pumps for an existing Wal-Mart. The 480V transformer is directly adjacent to the building and the Sprinkler Room is approx 80' away on the other side of the exterior wall. Is it NEC compliant to run conduit and conductors underground from the transformer to the exterior wall, travel along the outside of the building along the exterior wall and punch through the wall directly into the sprinkler room? The main question would that be considered "outside the building" therefore not requiring the Fire rating, Concrete encasement etc.? This is completely separate from any other services currently coming to the building and will not have any means of disconnect ahead of the Pump Controllers. The plan detail describes the installation in this way but I am not sure the conduit traveling along the exterior of the wall is considered "outside the building".

That is considered "outside" the building. Fire resistive cables are governed by Article 728 which will essentially say you must follow the UL listing for the system, which is called an FHIT XXX. That FHIT is a UL document that has instruction on how to install the system. All of these cable systems will require them to be followed "in the fire zone" and that you can deviate when you're "outside the fire zone". So you have to understand what a "fire zone" is. The best available defintion is in the IBC under "fire area". And that will be interior spaces only (with an exclusion for patios and such with a ceiling overhead) and is widely accepted as the correct definition. Also Article 728 only requires fire rated cable systems be installed "outside the fire rated rooms they serve". So if you're on the outside of building and punching into the room the cable serves, you can use normal wires (wet rated) and won't need fire resistive cable systems.

The FHIT's will say this:
"The hourly fire rating applies to cable passing completely through a fire zone and terminating a minimum of 12 inches beyond the
fire rated wall or floor bounding the fire zone."
The NEC says this:
"728.5 Installations. Fire-resistive cable systems installed outside the fire-rated rooms that they serve, such as the electrical room or the fire pump room, shall comply with the requirements of 728.5(A) through (H) and all other installation instructions provided in the listing."

In your case your outside the buidling, so that's not in the fire zone, or inside the room the cables are serving, so that's not necessary due to Article 728. Note, 728 doesn't give any hourly rating on that room either, so a 1 second rated room meets code.

 

[augie47]

For lengthy runs be sure to keep 695.7, voltage drop requirements, in mind.

 

[Boingo1972]

For lengthy runs be sure to keep 695.7, voltage drop requirements, in mind.

Augie47 is spot on! Just did a design in PA that was long (700 feet or so) and had to upsize the wires due to the 15% max at 115% load. Always try to use the actual nameplate on the pump (FLA/LRC) instead of the tables in the NEC. The nameplates are usually a bit lower and better.

 

[don_resqcapt19]

You also need to look at 695.4(B)(2)(a)(1) for the size of the service OCPD. You will have to get the code letter from the pump motor nameplate and use Table 430.7(B) to determine the locked rotor current, unless you motor nameplate is one of the very rare ones that actually give you the locked rotor current.