The Fire Alarm Telegraph Circuit

The Fire Alarm Telegraph Circuit

Part 2: Growth of auxiliary systems and development of municipal facilities for multipurpose use


Fire detection and alarm wed through sprinkler systems

A natural outgrowth of the municipal fire alarm system was its adaptation for the protection of public buildings and industrial property. Initially, municipal circuits were carried into such properties and there connected to standard street boxes, thus reducing the time required for turning in an alarm. But there were justifiable objections to running municipal fire alarm wires into these properties; notable was the relatively poor quality of wire and installation materials and techniques then available. Officials understandably feared that the quality of municipal fire alarm service would be impaired and yet they were anxious to meet the needs of influential taxpayercitizens.

Auxiliary systems

The records are not clear, but they credit a Mr. Rogers of Providence with the development in 1881 of the first “auxiliary” fire alarm system which permitted an interior non-code hox (basically a simple switch) to actuate a street box without the disadvantages previously mentioned. Improvements quickly followed and the first extensive auxiliary system was installed in San Francisco. In 1894 the Manhattan Auxiliary Fire Alarm Company was formed, and after a long controversy, connections were made to street boxes in the New York municipal system.

Interior stations in the auxiliary system were arranged to trip—from local battery power—“master” boxes on the municipal circuit, sending in to fire headquarters the master box code number. The weak link was maintenance of the interior system and specifically of the local battery. Periodic failures led to the development of the “shunt-type” master box, which permitted the municipal circuit to be carried into the protected property with the arrangement that an accidental break or an actual alarm would actuate the master box.

For many years thereafter, controversy continued as to the relative merits of the two auxiliary systems. Many chiefs preferred to rely on their own municipal maintenance crews to insure local system integrity rather than on the inexperienced and untrained local property personnel. The present-day high reliability of batteries and other power supplies and of cables, wires and installation procedures has reduced the controversy to academic proportions.

Defection and alarm wed

Earlier—in 1874—Henry S. Pannelee of New Haven invented the sprinkler head in an attempt to make fire contribute to its own extinguishment. Four years later the first practical sprinkler valves began to appear, along with many refinements to provide a fully automatic sprinkler system. During this period varied types of thermal electrical detectors were developed, chiefly open circuit and unsupervised; later, improved types were developed. The “fixed-temperature” type operated when the heat reached a predetermined temperature level; the “compensating” or “rate-of-rise” type responded to a certain rate of increase in temperature.


Central stations, proprietary systems watch over industry

These principles are still popular today, but the products then offered suffered greatly in comparison with those of the high-quality design and construction sold now. Today one may select from a wide range of reliable products in these categories, as well as from those employing modern techniques to detect the presence of smoke or the products of combustion.

As might be expected, these automatic detectors soon found their way into the auxiliary fire alarm circuits to help reduce the time from the start of fire to the alarm. Also, as sprinkler system reliability increased, means were found for connecting the alarm valve to the municipal fire alarm circuit to make fire tell on itself. These important developments helped tremendously in closing the gap between the start of fire and the arrival of the fire department. However, there was fear that the cure might be worse than the illness, as experience disclosed many false alarms and system failures. Chiefly these were due to lack of maintenance or poor maintenance.

There was need for insuring highquality performance from the interior systems, both electrical and sprinkler: batteries to be maintained; devices to be checked; tests to be made; valves to be supervised; and myriad other possible causes of failure to be guarded against. This led to the formation of companies offering the combined package of equipment and service and those contracting for service only. Each municipal system in a sizable population area afforded commercial opportunities for enterprising persons. And in the early part of the current century many such local companies were in existence as well as a number of larger central station companies.

The latter companies had found practical means for combining fire alarm with the plant supervisory and watch services which were becoming increasingly popular and thus had a two-stringed bow. To a property owner who essentially needed a watch or plant supervisory service, and who could acquire fire alarm protection also for a small additional cost, the concession in diluted quality of the latter service seemed minor. By 1930 the many local auxiliary fire alarm companies offering fire alarm services ex clusively were either swallowed up or absorbed by the fast-growing central station companies.

While smaller factories and build ings were installing city-connected auxiliary systems, the larger industrial concerns, with extensive property were being protected by self-sufficient systems of the so-called “proprietary” type. These were similar to those installed by the municipalities except for the more liberal use of automatic detection devices and frequently with combined supervisory and watch facilities. Many such systems were (and still are) user-owned and maintained; others are rented on a maintainedservice, annual-payment basis.

Interior alarm systems for private use can be (and the early ones were) extremely simple—no more complicated than the common door bell system. An actuating device (the pull station), an audible alarm (bell or horn), and a power supply are essential components. However, a wide range of variables are offered in the present-day “local” system.

The system can be “non-code,” sounding only a general alarm, or “coded,” sounding a distinctive alarm for each station or area. Also there are “pre-signal” systems, providing for an advance alarm at a staff location and requiring a secondary manual action for sounding the general alarm. Except where these local systems are required by law for protection of life or are intended to secure insurance premium reductions, the type and arrangement selected for a particular property depends on the preference of the building owner or, as often, of the seller. By and large the systems sold today as such adhere closely to the standards set forth by the National Fire Protection Association Committee on Signaling Systems and Detection Devices, thus assuring the buyer of acceptable quality standards. UL-listed components are likewise desirable.

Remote control

As noted above, the auxiliary system served admirably the need of the small factory or property wishing to get an alarm through quickly to the municipal fire department which had a street box alarm system. It did not meet the need of those in a municipality without such a system or where the plants were remotely located from the municipal circuits. To fill this gap, the so-called “remote station system” was evolved about 10 years ago and has become increasingly popular, not only for user-owned systems but also for those maintained by central station companies.

The remote station system employs separate wires (usually leased from the telephone companies) to transmit distinctive alarm and trouble signals to a municipal fire station. There is an attempt today to standardize on such equipment, particularly for the control panel at the fire station, thus simplifying supervisory responsibilities.

Certainly, industrial fire alarm is today a bigger and a faster growing industry than is the municipal fire alarm industry which sired it. This is in good measure due to the encouragement and financial support rendered by the insurance companies, which have been quick to recognize its worth in protecting insured values and to provide for this factor through attractive insurance rate reductions— some voluntarily bestowed, others forced under pressure of competition.

Broad programs needed

Municipal fire departments have contributed significantly to the high degree of industrial fire alarm protection existing today. Not only have municipal officials encouraged and advised, more importantly they have generously lent their facilities and services. Not always has this been accomplished without opposition, for there were—and perhaps still are— those who draw a narrow line between public and private, as if the private fire could be expected to remain such!

Certainly fire is no respecter of persons or artificial boundaries, and it logically should be so treated. Even as municipalities have generally taken over the distribution of water as a public service, perhaps the day is not far distant when they will view fire protection as of similar public interest and for the common good require, provide and administer it in all its phases. Not to adopt broad programs of this kind in areas of such national importance is to invite Federal intrusion to fill the gap.


“What do you want to accomplish?” is the only question

The municipal fire alarm system is much more than an alerting system; it is an organizer of the fire department in an emergency. Preplanned functions of the department are placed in systematic operation immediately on the first alarm, each company and individual fireman springing into action automatically. Modern equipment and technological knowledge is capable of expanding automation even further in today’s fire alarm system. The fire alann engineer has only to ask: What do you want to accomplish?

Circuits are versatile

The municipal fire alarm system, with its extensive wired circuits fanning out to all sections of the area and its extreme flexibility, affords an excellent opportunity for preparing a program for emergency area service. Many years ago it would have been unthinkable—perhaps dangerous—to use these circuits for other than the original purpose. Today, however, electronic improvements have taken broad and reliable form to permit many uses for these circuits and at little cost.

For many years fire alarm circuits between independent municipal systems have been interconnected to permit coded messages to be exchanged. A message from one municipality in the Boston area, for example, may be sent simultaneously to as many as seven neighboring communities. Each of these communities may similarly retransmit to others, and so on until the message has been spread throughout the wide area. Although such service today is primarily by code, no engineering problems are encountered in providing voice communication throughout the same interconnected wired network.

Currently fire alarm manufacturers are furnishing equipment for connection to fire alarm wires for police communication and for control of other municipal functions. Encoders and decoders connected in such fire alarm circuits provide means for controlling and supervising power station equipment, water works devices and other vital services. Traffic light control is well within the realm of possibility.

The municipal fire alarm system— never used to full capacity—may soon prove to be even a bigger and sounder investment than has previously appeared in helping to provide rapid area communication in emergencies. The ability of the system to transmit quickly and reliably codes for a predetermined message satisfies the need for reducing in-service time. Employment of radio utilizes important air time often needed for other transmissions; also whether radio can be used at all will depend on need for secrecy and other factors relating to the emergency. Voice on wire may well be a desirable or necessary substitute.

From early times, as noted above, automation has been an important feature of the fire alarm system. Looking ahead, one can visualize the use of modern computer techniques to further improve fire department planning and response. Information stored in the computer “memory” can readily be recovered and transmitted automatically to all responding and alerted stations, furnishing to them complete pre-fire plan instruction.

The first successful demonstration of the electric telegraph in its Washington-to-Baltimore debut was signaled with the words: “What hath God wrought?” Were Samuel Morse alive today, he might view with pride the fire alarm system which he helped to develop and ask that same question in its original form: “What wonder has God wrought?”

The Fire Alarm Telegraph Circuit


The Fire Alarm Telegraph Circuit

Samuel Morse started it and it’s still growing

Part 1: From hand-cranked boxes, to spring-wound coded signals, to the sophisticated central station of today

New York City was the first American city to provide means for sounding a general alarm of fire. In 1845 the city was divided into districts, each with a bell-equipped tower and an around-the-clock watchman. When a watchman discovered a fire in his district, he would strike the number of his tower on his bell; this signal would be passed along manually by each watch tower in the city. For outof-sight fires within buildings, the person discovering the fire ran to the tower, requesting the watchman to sound the alarm. Need for an improved method was apparent, and into this breach stepped the scientist.

Samuel F. B. Morse, Jr., in 1842 demonstrated, after several years of experimentation, the first practical means for transmitting electrical impulses over wires. Although the basic principles had been known for many years to scientists in many countries, Morse was first to apply them successfully in tests in New York in 1842. An appropriation by Congress a year later paved the way for the Washington-to-Baltimore wire line, signaling the beginning of the electrical telegraph.

Many with scientific interests were watching developments in this field. Among those was one Alexander Baine, an Englishman, whose 1843 patent envisioned the application of the telegraph to the neetl for sending alarms of fire. While his patent indicated the general principles later adopted, his original model was extremely crude and impractical. It remained for Dr. W. F. Channing, who had earlier and independently been advocating the telegraph’s use for fire alarm, to produce a workable system. His plan was first published in Boston in 1845.

In association with Moses G. Farmer, an expert mechanic and clever inventor, Channing developed his system. Boston appropriated $10,000 for an initial installation and later $6,000 additional for modifications and expansion to 39 street boxes. The first alarm from Box 57 was sounded on April 24, 1852 at 8:25 p.m. The Boston Transcript reported: “So successfully did the new system work in quickly summoning the department that little damage was done by the fires.” In 1855 Channing and Farmer obtained their patent, which was shortly thereafter purchased by John N. Gamewell who founded the company still carrying that name as part of its trade identification.

Cranking the alarm

The Channing-Farmer system was essentially as follows: The turning of a crank in the wooden street box passed a notched wheel over a telegraph key, alternately opening and closing the electrical circuit, thus transmitting the special signal predetermined by the notched wheel. (Although the original system provided for Morse code transmissions, this was soon altered for the faster and more reliable numerical code signals.)

At fire headquarters the circuit openings and closings caused electromagnets to send impulses over secondary circuits to bells, annunciators, registers, and other devices. The original system also provided for manual transmission from headquarters to fire stations, for testing facilities and for power supply. Except for lack of a clockwork box mechanism, the system was basically as it exists today.

American cities were slow to adopt the new fire alarm system—partly because of resistance to that which was new, but also because of the complications produced by the War between the States. While New York City employed Charles T. Chester in 1854 to install telegraph instruments for service between headquarters and fire and police stations and to watch towers, street boxes were not added until 1869. To Philadelphia, therefore, goes the honor for having the second fire alarm telegraph system, installed in 1855. St. Louis followed in 1858, and New Orleans and Baltimore in 1860.

It is oversimplification to say that today’s system is basically as it was conceived in 1852. Steady and important improvements have been made as experience dictated needs and as human ingenuity could devise.

Spring drive added

In the first system the notched wheel was passed over the signaling contacts by manual manipulation. An excited person invariably turned the crank at speeds beyond the limits of the receiving equipment; thus the alarm was “jumbled” or lost. Reduction gearing was soon added, at a 6:1 ratio, with instructions for the person at the box to “turn the handle 24 times slowly.” This only partially solved the problem.

A weight-actuated gear train soon followed, and shortly thereafter a spring-driven clockwork to drive the signal wheel. This clockwork mechanism went through many refinements from the initial “sector” drive with 2round capacity to its present prewound 36-or-more-round capacity.

Again, the early spring-driven mechanisms were inadequate in their actuating means. If the pull lever were operated more than once, an incorrect alarm would result. Ingenuity soon provided a “noninterfering pull.” But it was soon found, as systems and usage expanded, that there was need to guard against signal interference from a box operated on a circuit when another box was signaling. From the later-developed “distance noninterfering mechanism” (so-called to distinguish it from “pull noninterference”) several improvements followed rapidly, resulting in the Gardiner noninterference patent in 1875, which is the basis for today’s noninterference construction.

A major contribution to the art was made by John Ruddick who in 1889 developed the “successive” box movement. Previously, a box “pulled” on a busy circuit would be held out from signaling by the box first operated. Experience showed that the second box was sometimes operated for a second fire and the lost alarm caused serious fire loss, as the person attempting to turn in the alarm had no knowledge that he had not done so. The Ruddick mechanism was arranged to idle for a certain period and to send in its code signal after the first box had stopped signaling.

From this initial limited succession feature, the mechanism has been improved in steps until today when it will make attempts for as many as 36 rounds (revolutions) to signal. The Gamewell “three-fold” box has the added feature of signaling at the end of its 24th round, regardless of the condition of the circuit, to insure that its signal gets through before expiration of the box mainspring.

With few exceptions municipal fire alarm systems and many installed for industrial service utilize constantly supervised closed circuits with devices connected serially. This provides for efficiency and reliability. Experience has shown the cable and wire plant to be the weakest link in the system, with broken wires the most frequent cause for outage. Various methods were devised early in this century to utilize the unbroken side of the circuit and a ground path as a substitute circuit. Not until the highly successful C. E. Beach patents, however, were such attempts practical and popular.

These formed the basis for Gamewell’s “three-fold” system, providing full noninterference, quick succession and automatic grounding. Associated with proper equipment at the fire alarm central office, the three-fold box when pulled on an open circuit, will transmit a full and correct alarm.

Typical Class A alarm system that conforms to NFPA standards

—Courtesy Bliss-Gamewell

Operator console of central office, Salt Lake City, incorporates fire alarm, telephone and radio.

Before leaving the street box it might be of interest to note that early boxes were of the locked-door type to guard against malicious use. Keys were carried by policemen and firemen, and also were placed in the homes of persons living near the box. A sign on the box instructed the intended user where to find the key. Delays in alarms were frequent—and for understandable reasons. Furthermore, unauthorized persons often procured keys improperly and turned in false alarms. This apparently bothered the officials more than the delay in legitimate alarms, for in 1873, J. M. Fairchild developed a “trap lock” which trapped the numbered key used to gain access to the box trip lever, this identified the person to whom the key had been issued.

The keyless door

Two years later the more acute problem was solved by R. M. Tooker, who invented the keyless door. It had a handle on the outside which, when turned to gain access to the trip lever, sounded a door-mounted gong calling attention of persons nearby. Although this principle is still in use in some of today’s boxes, it was not popular because of lost alarms from people who, supposing the alarm had been turned in when the gong operated, failed to take the second step necessary, viz., to pull the inside trip lever.

Meanwhile, developments were taking place in the central office. Among the earliest was need for providing for noninterference between signals from two or more box circuits, and which were being repeated over secondary circuits. Various inventors made contributions, the most significant by Edwin Rogers in 1870, by Moses G. Crane in 1876, and by C. E. Beach in 1902. These repeaters were all of the electro-mechanical type with spring-driven movements and electromagnetic control. Not until about 1934 did the modem “electrical relay repeater” become popular. Today this repeating mechanism is customarily built into the main switchboard, but its functions are the same as the old mechanical repeaters.

Power supplies

Until about 1895 municipal fire alarm systems were powered by primary batteries. At first these were of the bluestone gravity type; later Plante or Edison batteries were used. In the early 1890’s lead plate storage batteries were adapted to fire alarm needs and Superintendent William Hamilton of the Hartford Fire Department was the first to arrange these for “duplicate” service with switching to permit one set to be used while the second was being charged. This method continued to be popular until about 1930 when a.c. rectifiers floating on storage batteries permitted a single set of batteries to carry the system and at increased life and higher efficiency.

In 1946 the late William Greenlaw, working with Gamewell engineers, installed at Beverly, Mass., a system with a vibrator power supply. Normally the power was supplied to the fire alarm circuits from alternating current through a transformer and rectifier filter combination. On loss of alternating current, de-energization of a transfer relay connected the standby battery to vibrators to supply power to the same alarm circuits.

Popular today are systems employing transistorized power supplies and a large common battery. These power supplies are infinitely more reliable at only a fraction of the cost of the early systems.

Central offices develop

It is a far cry from the original crude central office to today’s sophisticated facility. Not only have the individual devices been improved in quality but by appropriate combination and arrangement within the office, the efficiency of the service has been increased immeasurably. A generation ago, the fire alarm telegraph components occupied one area within the office, the telephone facilities another, and radio still another. Today fire alarm engineers are trained to consider and design around complete communication needs, combining these and other facilities indiscriminately and in a manner best meeting the needs for convenience, efficiency and economy.

The use of voice communication for supplementary service had also been developed by the fire alarm industry and fire service users. Initially it was limited to talking from street box to central office over fire alarm wires. In the 1930’s it was found practical to adopt amplifiers and receivers for service between and within central office and stations. Within the past few years developments in the electronic field have led to the use of fire alarm circuits for signaling and talking from street boxes to remote locations as supplementary emergency communications service.

Standards adopted

Prior to 1900 there was no standard fire alarm system. Manufacturers catered to— and doubtless encouraged —individual preferences on the part of customers. While some of this might reasonably be expected in a new and small industry striving to improve its products, frequently the need was more imaginary than real. This complicated the situation for the National Board of Fire Underwriters (now the American Insurance Association) which in 1904 began actively inspecting and testing municipal fire alarm systems.

To meet this problem and to insure adherence to minimum quality standards, the National Fire Protection Association’s Signaling Committee in 1908 produced standards by which installations were measured and graded. This committee, still active, annually reviews its standards to keep them in line with technological advances.

(To be continued)