#115 – Testing: Automatic Transfer Switches for Fire Pumps

by Will Strickler

Electric fire pumps, as we all know, are an essential part of any fire protection system that they are installed in. It is one of the many parts of a system that is designed to run until complete destruction. However, there is one thing electric fire pumps cannot function without…they need a reliable power source to keep running. Of course, there are many installations out there where an alternate power supply was not necessarily needed due to the main power source being of reliable nature, code requirements or Authority Having Jurisdiction (AHJ) approved criteria. On the other hand, where the power is not so reliable or simply required by code or the AHJ, the Automatic Transfer Switch (ATS) would be installed. The ATS, if needed, is very crucial part of guaranteeing the fire pump can do the job it was built for and it needs our support! An ATS needs to be tested just like most everything else in this industry. So, let’s take a look at some problems that could arise and some important testing requirements that can help us support the ATS to ensure that the system works as it is designed.

An ATS is something that is often over looked and left un-tested. Over the past two years alone I have been involved in several fire pump annual tests and have had to fail the ATS part of the test, as there were potentially dangerous issues that arose. For instance, wire leads from the generator that had phases reversed, wire to generator never installed from the ATS, start wires from the ATS to the generator disconnected or missing, and even a step-down transformer incorrectly sized and installed. Those are just some of the few that have been found at this time. Most of these issues should have been identified during the field acceptance test of the fire pump. Not only should the ATS be transferred during the acceptance test while the pump is flowing at peak load (NFPA 20, 2016 & 2019 Edition, Section, the alternate power supply also should be used/tested during at least six of the twelve manual and automatic operations (NFPA 20, 2016 & 2019 Edition, Section Following the acceptance criteria in NFPA 20 for fire pumps, with an ATS, many problems can be found and repaired. Therefore, if you install systems per a certain standard/year, make sure that it is tested the way it should be.

Although a few of those situations above could have been changed after such acceptance tests, with the lack of evidence, it makes the actual time of events unknown. This would be where the NFPA 25 would be beneficial in finding problems and preventing future problems. The NFPA 25, 2017 Edition Section covering the ATS testing during the fire pump annual test, has been updated since the 2014 Edition, Section Both editions require testing of the ATS with the fire pump operating at peak load, the 2017 edition simply updates one subsection and adds another. The 2017 edition adds that voltage, amperage (where an external means is provided on the controller), the RPMs and the suction and discharge pressures to be recorded on the fire pump test results with all other required information. So, if you are in a state or jurisdiction that has adopted the NFPA 25, 2017 edition, make sure to include those results on your fire pump test reports. The previous editions require testing the ATS in the same manner– just not recording all the data on the test results as it is in the 2017 edition.

There is another code that needs mentioning, as sometimes it can be overlooked, NFPA 25 Section It states an ATS shall be tested and exercised in accordance with NFPA 110. This is the same in both the latest editions of the NFPA 25 and all the way back to the 2002 edition. Furthermore, if we look in to the NFPA 110, 2013 or 2016 editions, it clearly states that transfer switches shall be operated monthly (NFPA 110, 2016, Section 8.4.6). The next section states that the monthly test shall consist of transferring from primary position to the alternate position and back again (NFPA 110, 2016, Section This is simply a test of the switch itself– not of the performance of the fire pump. This test can be completed once a month while you are doing your monthly or weekly testing of the fire pump.

I am certain there are a lot of companies and inspectors who already knew this and are currently implementing it in the field, but for those of you who aren’t– be sure to check your appropriate standard and perform the test, as they are vital to the performance of fire pumps and the fire sprinkler system. The electric fire pumps, with automatic transfer switches, need our help to ensure that the alternate power source is there when it is needed. We are all in this industry to protect life and property, so let’s make sure we do all we can to do just that.

References I used throughout the article:

  1. NFPA 20 Standard for the Installation of Stationary Pumps for Fire Protection 2016 Edition
  2. NFPA 20 Standard for the Installation of Stationary Pumps for Fire Protection 2019 Edition
  3. NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems 2014 Edition
  4. NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems 2017 Edition
  5. NFPA 110 Standard for Emergency and Standby Power Systems 2013 Edition