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Low-Voltage Electrical Concerns: The Good Old Days

By Bill Adams

Twelve-volt electrical problems have cursed fire departments since day one. When the beacon ray started slowing down on the 1948 pumper, it was time to crank up the throttle. When the headlights on the 1955 squad truck started dimming and looking yellowish, the driver turned them off; then the defroster, heater, and radio. The 1942 pumper’s siren-light was replaced with a four-lamp rotating light and the largest mechanical siren known to mankind. Hit the siren, and all the lights dimmed and the electric windshield wipers stopped. Most “fixes” addressed the immediate problems and not the causes. When parked, increasing the throttle to 1,100 rpm usually recharged batteries enough to get rigs back to the barn. Monitoring electrical issues by sight alone is like a pump operator checking the pressure of an incoming supply line by leaning a knee against it. Not too accurate, and you might get hurt.

Today, there are load managers, monitors, flashing lights, and alarms warning of impending electrical problems and preventing catastrophic shutdowns. Purchasers don’t have to spec every one of them because they’re all required by National Fire Protection Association (NFPA) 1901 Standard for Automotive Fire Apparatus. However, an apparatus purchasing committee (APC) not addressing the whys and wherefores of low-voltage electrical systems may be doing itself and the fire department an injustice and a disservice.

Writing Electrical Specs
The alert tone sounded followed by, “Attention all stations: Engine 1 is out of service until further notice—electrical problems.” The chief grumbled, “Here we go again. Electrical problems are killing my budget.” Attempting to prevent further problems, he directed the APC to tighten up the electrical specifications for their new pumper. He suggested looking at other manufacturers in case the troubles were particular to the apparatus regularly purchased. His intentions were commendable. However, he failed to address a possible cause of the problems. Electrical issues are not necessarily an apparatus manufacturer’s shortcoming or the result of ineffectual specifications. It could be the lack of a comprehensive apparatus maintenance plan including periodic testing of electrical systems. More on that later.

The aforementioned APC dutifully studied NFPA 1901’s Chapter 13 addressing low-voltage electrical systems and wrote verbatim most of its seven pages of requirements into their specs. Other than gleaning personal knowledge from reading the data, there was no value in doing so. Nothing was gained. Stating the vehicle must be NFPA 1901 compliant requires bidders to meet all its provisions.

Chapter 13 has one place that may require a purchaser’s action when writing specs. Section 13.3.3 lists the minimum electrical requirements when in a stationary mode during emergency operations. Item seven says that other electrical devices defined by the purchaser as critical to the mission of the apparatus can be added to the list. Purchasers seldom do.

The NFPA’s requirements are minimums. They do not specify levels of quality, workmanship, or component parts details. Most apparatus manufacturers’ specifications describe their electrical installations in detail. Many exceed NFPA 1901. If more than a minimum electrical installation is desired, the responsibility rests with purchasers to evaluate the electrical system components and methods of installation offered by various manufacturers.

A comprehensive detailed description of an electrical system in purchasing specifications should ensure a level of quality. A downside is it may restrict competition. An unintended consequence is an APC can look hypocritical—or even foolish—by specifying components it knows little about, can’t define, or explain why they were specified. Don’t be censured for specifying components just because they were recommended by a preferred vendor. You may be accused of “drinking the Kool-Aid.”

Electrical Load Analysis Confusion
NFPA 1901 sentence 13.15 says that a written electrical load analysis shall be provided at the time of delivery. But, sentence A.13.3.2 in the appendix says the purchaser should review the performance of the alternator with the load study provided by the manufacturer for on-scene and responding modes. This appears confusing. NFPA 1901 does not require bidders to provide an electrical load study with their proposal. If a load analysis is not required with the bid, how can it be compared it to an alternator proposed in the bid? If a purchaser is going to specify an alternator size in the purchasing specs, an electrical load analysis should be done prior to writing specifications.

Sentence A.13.3.3.1 (7) says the purchaser and manufacturer should work together to determine how to reduce electrical loads when larger alternators are not available. I also interpret this to mean after a bid opening. That doesn’t make sense. Working amicably may not always be possible especially if a nonpreferred vendor is awarded the contract. Purchasers should interact with responsible and knowledgeable vendors prior to a bid opening. Astute buyers might alleviate confusion and possible animosity by determining electrical requirements—including an alternator size—prior to writing specifications. At the least, specify an electrical load analysis with the bid.

NFPA 1911
Having a working knowledge of NFPA 1901 is laudable. Understanding NFPA 1911, Inspection, Maintenance, Testing and Retirement of In-Service Automotive Fire Apparatus, is commendable. It should be required reading for those who purchase apparatus, repair and maintain them, and work off of them. I call NFPA 1901 the bible of fire truck purchasing. NFPA 1911 is like the ten commandments—it holds the principles of instruction on how to keep the fire truck running. The best rig in the world can be rendered useless by improper maintenance. Knowing the particulars of maintaining and testing 12-volt electrical components after a rig has been in service will help an APC understand and appreciate why those requirements are specified in the first place.

NFPA 1901 section A.13.3.4 says: “The unexpected shutdown of a fire apparatus can place firefighters in mortal danger and seriously affect the fire attack.” The sentence may have more relevance for apparatus that’ve been in service for several years, hence, the importance of NFPA 1911.

BILL ADAMS is a member of the Fire Apparatus & Emergency Equipment advisory board, a former fire apparatus salesman, and a past chief of the East Rochester (NY) Fire Department. He has 50 years of experience in the volunteer fire service.

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