New ISO Grading Schedule Updates Protection Values

New ISO Grading Schedule Updates Protection Values

The Insurance Services Office “Grading Schedule for Municipal Fire Protection” that went into effect May 1 puts more emphasis on fire prevention and raises the fire department to the same level as the water department in evaluating the total fire defenses of a municipality.

At the same time, slightly less weight is given to fire service communications. The old concept of the “principal business district” has been discarded in recognition of the decentralization of high-value districts in cities that has resulted in the need for large fire flows in several areas. Therefore, the new Grading Schedule seeks to measure a municipality’s ability to fight fires throughout its area rather than mostly in congested business districts.

Other changes include a change in manning of apparatus, greater concern about training and pre-fire planning, the end of the requirement to have alarm boxes in residential neighborhoods, duration of fire flows, and an increase in hydrant areas where the fire flows are below 6000 gpm, as well as 10,000 and 11,000 gpm.

The number and distribution of engine companies represents a major change from the old schedule and more closely approximates the requirements in Special Interest Bulletin No. 315, published in 1963 by the National Board of Fire Underwriters.

The new Grading Schedule replaces the “Standard Schedule for Grading Cities and Towns of the United States with Reference to Their Fire Defenses and Physical Condition,” which was published in 1956 and amended in 1963 and 1964. The shorter title of the new schedule reflects a modern and practical approach to the problem of evaluating the fire defenses of municipalities.

Copies available

The “Grading Schedule for Municipal Fire Protection” can be bought for $3.50 from the publisher, Insurance Services Office, Municipal Survey Service, 160 Water Street, New York, N.Y. 10038.

The new Grading Schedule, explained Edwin N. Searl, vice president of the ISO Commercial Property Department, is expected to have little effect on a municipality that has kept its fire protection in step with its growth and needs. He said that the changes are expected to balance out so as not to have any great overall impact on grading classifications that were the result of recent inspections.

Searl added that the new schedule reflects consultations with organizations outside the insurance industry, such as the International Association of Fire Chiefs, National Fire Protection Association, American Water Works Association, National League of Cities and International City Management Association.

As in the past, the grading system uses 5000 deficiency points which are assigned to reflect the divergence of conditions from the Grading Schedule. Fire departments have attained equality with water departments under the new schedule, which assigns 1950 points to each. Previously, fire departments were responsible for 1500 points and water departments, 1700 points. Fire service communications has 100 points less than were assigned to fire alarm in the old schedule. A new feature, fire safety control, replaces the fire prevention, building department and structural conditions categories previously used. Table I shows the new assignment of points.


Relative Values and Maximum Deficiency Points

Change in manning

The required strength of engine and ladder companies is six men for each company under the new Grading Schedule. The differences between high-value and other company strength has been dropped, and men assigned to ambulances or “other units serving the general public” can be credited to department strength according to the extent they respond to alarms and do fire duty.

Hose companies that are credited in lieu of engine companies are required to have five men on duty. In the cases of both engine and hose companies, the manning represents one less man than previously required for high-value companies but one man more than required before for other companies.

Training emphasized

Reflecting an increased emphasis, the training section calls for “a complete, uniform training program under the close supervision of a competent officer.” In addition to regular classes and drills at a training facility and at fire stations, this section of the Grading Schedule also requires “special classes for new men, officers, operators, and drivers.” The training program must be “commensurate with the fire potential” in the area so that the department can handle fires efficiently.

The training section also ties in building inspections with pre-fire planning. Records of “systematic and frequent” building inspections should include notes and sketches that can be used in company training.

An idea of the increased importance given to training and pre-fire planning can be gained from weight given deficiency points. Under the old schedule, ½ the deficiency scale was used to reflect inadequacies in these activities, but the new Grading Schedule applies 1½ of the deficiency scale.

Alarm boxes

A major change in communications requirements in the new Grading Schedule is the elimination of deficiency points for failing to have alarm boxes in residential districts. This in effect eliminates the need for street alarm boxes in residential districts. This is done indirectly by stating in Item 3 in the Fire Service Communications section: “Distribution of boxes in commercial districts shall be in accordance with this Standard” (NFPA No. 73).

There is no mention of alarm boxes in other districts until Item 10, the last in the Grading Schedule communications section, which provides for up to 20 points credit “where boxes are installed in residential districts.” So while boxes are not required in residential districts, a municipality can acquire points for maintaining boxes in such districts. It should be noted, too, that boxes are still required at schools in residential districts.

Fire flow durations

One of the greatest changes in the new Grading Schedule is the required durations of fire flows. The old schedule required 10 hours duration for fire flows of 2500 gpm and more. The new schedule demands this time only for fire flows of 10,000 gpm or more. Below 2500 gpm, the old schedule called for 9 hours for 2250 to 2499 gpm and ranging downward to 4 hours for less than 1250 gpm. Now the durations decrease, from flows below 10,000 gpm from 9 hours for 9000 to 9999 gpm to 2 hours for 2500 gpm and less. Table II shows the fire flow durations in more detail.


Required Fire Flow Duration

Hydrant distribution

Hydrant distribution has been liberalized to the extent that the average area served by a hydrant has been increased for some fire flows. For example, for a fire flow of 5000 gpm, the average area per hydrant is increased from 85,000 to 90,000 square feet. For fire flows less than this, the hydrant areas are now larger. From 6000 to 9000 gpm fire flows, and 12,000 gpm fire flow, the hydrant areas are the same in both the old and new schedules. The new schedule increases the hydrant areas by 2000 square feet for both 10,000 and 11,000 gpm fire flows. Table III shows hydrant areas.


Standard Hydrant Distribution

Pumper capacity

Instead of demanding pumper capacity equivalent to two-thirds of the required fire flow, the new Grading Schedule calls for “total pumper capacity of not less than the basic fire flow established under the water department section of the schedule and adds that “additional capacity may be needed when there are individual buildings or groups of buildings requiring higher fire flow.” In cities where provision for fire flow for simultaneous fires is applicable, the pumper capacity must be “not less than the sum of the fire flow requirements for the simultaneous fires.”

A change in this area is the credit for the full capacity, instead of half capacity, of reserve pumpers that are available for immediate service and have not been used to reduce a deficiency in in-service pumpers. However, the total capacity of reserve pumpers credited cannot exceed one-third of the required pumper capacity for the municipality. Also, direct hydrant streams that meet established standards are acceptable for credit toward decreasing deficiency in pumper capacity.


Changes have been made in both the amount of hose required and its expected service life. The new Grading Schedule states that a fire department “shall provide at least 2400 feet of 2 1/2-inch (or larger), 600 feet of 1 1/2inch, and 200 feet of booster hose (or equivalent preconnected larger hose) for each of the existing engine companies.” The schedule also states that the hose will be distributed so that at least 1200 feet of 2 1/2, or larger, hose, 400 feet of l 1/2-inch hose and all the booster (or preconnected larger) hose shall be carried on each engine while the remainder of the company’s hose “shall be kept at stations or conveniently located hose depots.”

This represents a change from the requirement in the previous grading schedule for 1000 feet of 2 1/2-inch hose on each engine while NFPA Standard No. 19 called for 1200 feet of 2 1/2-inch hose. The requirement to have a “complete spare shift” of hose in reserve for each company has been dropped.

The 2 1/2-inch hose service life that “should be expected under normal conditions of use” is now set at 10 years. Previously, it was seven. The new Grading Schedule mentions 1½inch hose service life for the first time and sets it at five years. Hose older than one-half its expected service life that has not been tested annually at a minimum of 250 psi “shall be considered as being in unreliable condition.”

Response to alarms

The new Grading Schedule calls for the same number of companies to respond to alarms “irrespective of the type of alarm, whether box, telephone, automatic Fire alarm, or sprinkler water flow, except that where an alarm by telephone or other means indicates definitely an automobile fire or other minor fire not in or involving a building, the response may be only one engine or ladder company.”

The response distances are based on the fire flow for the district. Table IV shows the response distances for various fire-flow districts.


First-Due Engine and Ladder Company Response Distance

*Where there are less than 5 buildings of a height corresponding to 3 or more stories, a ladder company may not be needed to provide ladder service.

May be increased to 2 miles for residential districts of 1and 2-family dwellings, and to 4 miles where such dwellings have an average separation of 100 feet or more. May be increased to 3 miles for residential districts of 1and 2-family dwellings, and to 4 miles where such dwellings have an average separation of 100 feet or more.

Distances shall be reduced “if a severe life hazard exists; if traffic routing and congestion, topographical features, man-made barriers such as railroad and highway structures, other local conditions hinder response; or if other circumstances peculiar to the municipality or particular district indicate that such a reduction is needed.”


Reflecting the universal use of radio, the new Grading Schedule requires transceivers in all apparatus and chiefs’ cars. The old schedule granted a reduction in deficiency points for fire departments in municipalities below 50,000 population that did not have enough radios.

Furthermore, portable transceivers “shall be provided in departments requiring 13 or more companies, and may be needed in smaller departments depending upon local conditions.”

The maintenance of radio communications with all companies on the fireground, including mutual aid companies, is considered in rating fire operations. The section on fire operations also calls for “appropriate use of private fire protection systems.”

The use of radio and telephone alarm systems to call volunteers at their residences and places of business can be “considered” under the new schedule, which says that “judgment as to suitability shall be on the basis of equipment used, tests, and experience.”

Continued on page 67

Grading schedule

continued from page 47

Fire safety control

The section on fire safety control states that there should be laws or ordinances regulating “the manufacture, storage, transportation and use of hazardous liquids, gases, and other materials, including the handling of combustible wastes, and to properly control building construction and electrical, heating, and ventilating installations.” Lack of enforcement, the Grading Schedule declares, “is considered equivalent to absence of laws and ordinances.”

The Grading Schedule calls for comparison of laws and ordinances with the Fire Prevention Code of the American Insurance Association and also National Fire Protection Association standards. Inspections should be made as frequently as necessary for proper enforcement of fire prevention regulations and, in general, the more hazardous occupancies should be inspected four times a year, the schedule states.

The deficiency points assigned to various features affecting fire safety have been increased in most cases. This is a reflection—or a result—of the increase in the number of deficiency points assigned to fire safety control, 650 points—an increase from the 350 points assigned to fire prevention in the old schedule.

Laws and ordinances affecting building construction, electricity, heating and ventilation are evaluated in relation to the National Building Code of the AIA, the National Electrical Code, and NFPA standards.

Other changes

The “possibility of strikes” has been added in a section on conditions adversely affecting fire department operations.

The new schedule says that criteria in NFPA Standard No. 19, “Automotive Fire Apparatus,” “shall be used as a guide for determining the suitability of pumpers, ladder trucks, and other fire apparatus.”

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