Should Fire Pump Controller Be NEMA Type 3R?

7/20/2026

While NFPA 20 requires a minimum NEMA Type 2 enclosure for fire pump controllers, an alternative view has been expressed that a "NEMA Type 3R" enclosure should be provided where the fire pump room is sprinkler-protected.

The rationale is that activation of the sprinkler system during a fire event may subject the enclosure to water spray similar to rain exposure, for which NEMA Type 3R enclosures are designed to provide protection.

What is your thought on this?

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6 Comments

Glenn Berger

7/20/2026 08:17:47 am

NEMA 3R is excessive. Its use is required by Electricals with the fear that any sprinklers in the space will only spray inside electrical enclosures.

The use of NEMA 2 enclosures is more than proper for fire pump enclosures.

anthony

7/20/2026 08:23:32 am

Seems excessive to me. The odds of water ingress is relatively low as sprinkler distribution patterns are relatively well know and the dynamic wind factors are not present in a pump room. Nema 2 is drip/splash proof which should be enough for the ~ .1gpm that hits the box maybe. We are not building explosion proof rooms or pumps rooms that are expected to withstand a hurricane without a structure.

I'm seeing more and more extra mile what ifs in this business recently. The code is set to provide a reasonable standard of safety not prevent all possibilities from occurring.

Jack G

7/20/2026 10:41:52 am

Yes I agree it is excessive. What I try to do is make sure the sprinkler head is not directly over the panels and follows the electrical clearances for panels/ voltage based on NFPA 70.

Jack G

7/20/2026 11:04:15 am

I can understand recent concerns as the pump room design density depends on the overall building classification.
Light haz is .1
Ordinary haz is .2
Extra haz is .3 or .4
A diesel fire pump room is another situation.
Due to fuel tank/s and piping it is usually a .4 density for the room and area around it adding hose streams. The area can be reduced utilizing high temperature sprinklers.
If the room is of fire rated construction with fire rated louvers then the room design method is the designers “ preferred” method.
FM 8-9 references a .25 density .
NFPA 13 a .25 density for nuclear fire pump rooms.
So there could be an ample flow of water that could cause nema 2 panel failure.
In small pump rooms I ve installed baffles on the sprinklers to directly limit the amount of direct water contact.
If not a diesel I “go” for the light haz classification and the .1 /nfpa 70 approach with the nema 2 controller.

Wes

7/20/2026 11:18:45 am

To Anthony's point, even at a higher density (remember one or two sprinklers will have a FAR higher effective density than 0.10 gpm/sqft) - it's still a limited risk hypothetical situation.

NEMA 2 is a drip/splash resistant enclosure. It's not as if a sprinkler activation automatically renders the fire pump unusable. To my knowledge, we also don't have a recent or published example suggesting code is inadequate here, correct?

If there were a fire event that shows code is under our wanted level of safety, that'd be a concern and driver here - but based on the writeup and what I know today, this seems like more 'what if' analysis over a substantial risk or recent documented event.

Janak Patel

7/22/2026 11:52:59 am

I would suggest to make this as a formal proposal to NFPA 20 Code Committee so a thorough discussion can be be done on the subject, and necessary changes made.

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Should Fire Pump Controller Be NEMA Type 3R?

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