FIRE AND LIFE RISKS IN ELECTRIC LIGHTING AND TRANSMISSION OF POWER.
(A Paper Read Before the Electric Club„November 4, by Dr. GEORGE H. BENJAMIN.)
At the regular meeting of the Electric Club, held in this city, on the evening of November 4, Dr. George H. Benjamin, a member of the executive committee, read a paper on the above-named subject. At its conclusion a Colonel Morrison, the representative of an electrical company, pronounced the statements contained in the paper exaggerated and untruthful, whereupon considerable excitement in the club ensued. This prevented the consideration by the club of the rules submitted by Dr. Benjamin. We present herewith the full text of the paper, with the rules submitted by Dr. Benjamin :
In 1882, the Board of Fire Underwriters of the city of New York adopted a series of rules relative to the precautions to be observed in the introduction of the electric light into buildings, and which were published at the time, and with which you are ail doubtless familiar.
However well these rules may have been suited to the date of their promulgation, I believe it will be generally admitted that they are unsuited and inadequate to the present needs. With all new industries or the practice of new arts, it has been the rule to allow the utmost latitude and to impose as few restrictions as is possible compatible with public welfare, this with the idea of lending encouragement and facilitating the Introduction of such new art or industry ; but when after a time the industry or art has become well understood and established] on a-firm commercial basis, further and supplemental restrictions are generally imposed with the intention of making the employment of such art or industry absolutely safe for all concerned, those engaged in the practice thereof, as well as those using or being benefited thereby.
When the dangers arising from the employment of electric currents of such quantity or electro-motive force, as are required in electric lighting, were first pointed out through the medium of the public press, there was a great hue and cry raised by those engaged in the business, and unstinted abuse was heaped on the heads of the unfortunates who had dared to have tbo temerity to advance such radical ideas. Time works wonders, and I doubt not that to-day, even those employed in the business of electric lighting, see and feel the necessity of precautionary rules and likewise tho advisability of their most rigid enforcement. If anyone present sees fit to question my premises as stated, I would respectfully refer them to the disastrous fires and terrible accidents which have been lately recorded in the daily press—fires which caused the destruction of large amounts of valuable property, and accidents by which men were unnecessarily deprived of life. I say unnecessarily as regards life, as the possibility of such slaughter should be guarded against by absolute prohibition, and, if necessary, by statutory enactment, making it a penal offense to direct or employ men, however experienced in that class of electrical work, where the slightest oversight or unavoidable slip means sure and instant death. Some of you may be inclined to argue that employers should not be held responsible for the carelessness and negligence of their men ; that the men seek the employment, well kocwing he terrible dangers to which they will be subjected. To them I say that the root of the matter should be sought. The struggle for existence and the difficulty in obtaining employment at the present time is a most potent factor in causing those in need to seek and obtain situations, however great the risk entailed. If the remedy were directed toward the fountain-bead, and the principal or management of the company employing such dangerous currents were held personally responsible, then they would make it their business to see that no unnecessary risks were entailed, and they would in effect become guardians of their men. That familiarity breeds contempt is an old saw, and to warn the average electric light line man or machine attendant to be carefnl is’sure to provoke a derisive smile. “All right, I’ll look out for myself,” was the answer of an old and experienced employee in a Western city a few weeks since. In less than two minutes thereafter he was stone dead. Thought the circuit was open. If the president of the company had been fully aware that he would be held responsible for such an accident, he would have seen to it that the circuit was open, and a human life would not have been needlessly sacrificed. Some may argue that there are occasions when it is impossible to open the line without serious loss or public inconvenience, and that repairs may become necessary when the line is in full operation. To those I say that there can no occasion arise in which an employee must necessarily risk his life. What does it matter if one, twenty, fifty or any number of lights be cut out? Nothing compared to a human life, and particularly as I maintain that no condition can arisr where the necessity of cutting out any such number of lights is obligatory.
When a man, under our laws, is tried for his life, the law presumes him innocent. There are many cases on record where hundreds of thousands of dollars have been expended to save the lives of men probably not as worthy as either of the two poor fellows lately so wantonly slaughtered. More money, yes twice over, than would have been requ red to buy out and obliterate the electrical companies owning the plant which caused theit death. The good of the many (the public) may at times require the sacrifice of the lives of the few, but the good of an electric light company is not the good of the public, and it is incomprehensible that a mere commercial concern should be allowed, by gross carelessness or ignorance, to sacrifice the life of even the meanest of human beings. Therefore, I contend that stringent and prohibitory means should be adopted to make such accidents in the future an impossibility, and further, that such rules should have the cordial support of everyone having the true interest of electric-lighting or the transmission of power at heart. So far as the risks from fire are concerned, it is not necessary to enumerate them. Unfortunately, sad experience has made them only too well understood. Careless, stupid, and one may say criminally loose methods of wiring, have been the rule rather than the exception in this country. Of course, with some notable exceptions, and all those who have carefully studied the subject and are conversant with the needs, feel that the enforcement of proper and stringent rules will not only allay public fears and restore confidence, but likewise materially benefit the industry.
I contend, gentlemen, that we should look upon this subject in a broad light, and free from the narrow prejudice of business. We should recognize the necessity and not attempt to evade the responsibility. To make an electric plant perfectly safe may necessitate slightly increased cost of construction—although personally, I am inclined to doubt the fact. But even admitting such to be the case, the perfect immunity from danger, the decreased cost of insurance and the general confidence engendered in the public mind, will be a good interest upon such additional outlay.
The rules which I would submit to your consideration, are as follows, and have been written after a careful examination of the rules of all the fire boards and underwriters associations of the world. I have endeavored to make them as concise and clear as possible, and with the intention of providing as few onerous conditions as are compatible with absolute safety to life and ptoperty. Such rules are comprehended under the headings: (1) Rules to be observed in conveying currents of considerable quantity or electro-motive force in and through buildings. (2) Rules to be observed in locating and constructing aerial and underground conductors. (3) Rules to be observed to prevent accidents to life or bodily injury.
I.-RULES TO BE OBSERVED IN CONVEYING CURRENTS OF CONSIDERABLE QUANTITY OR ELECTRO-MOTIVE FORCE IN AND THROUGH BUILDINGS.
The degree of E M. F. that may be employed in an electric circuit within any building should not exceed 100 volts for alternating currents, or 200 volts for continuous currents. No departure will be allowed from this rule except by special permit, and then only for arc installations in large buildings where the whole plant is absolutely removed from public interference.
The conductivity of all wires should be such that 100 per cent more current can be transmitted through them than that estimated as their proper carrying capacity, without increasing their temperature above 150° F.
No naked conductors allowed in buildings.
All light and power circuits must be entirely metallic, and of properly insulated wire. The employment of gas, water or steam-pipes, or the earth as a part of circuit, is positively prohibited.
All conductors should be thoroughly well insulated with a material or materials as non-inflammable as possible, and which will not fray or become loose, melt at a low temperature (below 150 degrees F.) or absorb moisture.
All conductors that are exposed to moisture, must be provided with a waterproof insulating covering.
Where practicable, all conductors in factory or similar buildings shall be so placed as to be readily inspected and tested.
No conductor, whether bare or insulated, shall be laid in wet cement, plaster, mortar, or other similar material.
All conductors carried through or within walls, floors or partitions, must be inclosed in separate metal, earthen ware, terra-cotta or asbestos board tubes, or their equivalent, and which should be slightly larger in their inside diameter than the conductors they are designed to carry. Conductors should not be placed above each other in’such a manner that water could make a cross section. Especial care should be taken to protect all concealed wires from mechanical injury.
Conductors conveying currents of considerable E. M. F. or quantity as for arc lights, power, charging of storage batteries and the like, excl uding secondary distribution, should be placed at least six inches apart, the same distance from conducting bodies, and at least two feet from other wires of smaller diameter placed parallel therewith.
Conductors conveying alternating primary currents of high E. M. F. must be kept a minimum distance of twelve inches from each other and inclosed in separate highly-insulating fireproof casings.
Conductors conveying currents for incandescent lighting and having a less E. M. F. than 200 volts, and run along walls or other exposed supports. should be placed at least two and one-half inches apart and a similar distance from all other wires or metallic bodies, except as provided in Rule 9.
Conductors for arc or incandescent lighting currents should he placed in grooved mouldings, or casings of wood or dry plaster or like material, preferably arranged along the cornice line, and in such case there should be a septum of the wood or material, having a thickness of three inches for arc currents and one-half of an inch for incandescent currents, between the wires. Wooden mouldings may be rendered fireproof by painting them with a solution of tungstate of sodium in water.
Single or twin wire insulated conductors may be carried through electroliers or gas fixtures, but especial care must be taken to insulate such conductors from the metal parts of the fixtures.
The location of all concealed conductors should be plainly designated by an appropriate mark.
No metallic staples, nails, hooks or devices for attaching and supporting electrical conductors should be employed in buildings. Wooden cleats or porcelain saddles must be provided. Two conductors conveying high potential currents should never be included in the same saddle or cleat.
Twin insulated wires may be employed in branches feeding single incandescent lamps in parallel of the main circuit.
All joints should be mechanically and electrically perfect ; the ends cleaned, united by solder (resin flux employed) and wrapped with insulated tape.
Safety fuses should be provided at both points of junction of a branch circuit with a main circuit, and the conductivity of such fuses should in no instance exceed fifty per cent of the current designed to operate the devices in circuit.
Where practicable, all safety fuses for each room should be placed in a conveniently located fireproof box, so that they can be inspected or renewed without inconvenience or injury to the premises.
A cut-out switch which can be operated by the firemen or police, must be placed in the circuit in a well-protected and accessible place.
Magnetic cut-outs or circuit breakers should be used in preference to fusible strips on arc or power circuits, and should be adapted to be thrown into action by any increase of current amounting to fifty per cent or less, as specially required.
Magnetic cut-outs, for use in secondary distribution circuits, should have double poles and arranged to act at twenty-five per cent above the normal current, and be placed as near the entrance of the primary conductors into the building as possible.
Where incandescent lights are run on arc light circuits, fastening or attaching lamps to any gas or other metallic fixture which may be in electrical connection with the earth is prohibited.
Distributor boxes from arc light circuits must be convenient for access, kept free from moisture and dust, and as far removed as is possible from other electrical devices, pipes, metal, etc., or earth connections.
Distributor boxes must not be placed in any circuit wherein the E. M. F. of the current transmitted exceeds 1000 volts.
Distributor boxes must be arranged to automatically cut out the arc current, should any defect arise or accident occur either In box or incandescent circuit.
In working distributors, an ampere-meter should be Included in the circuit and connected with an audible alarm, so that warning will be immediately given should the current exceed the standard amount.
AH switches, cut-outs, safety fuses, resistance boxes, distributors, regulators and the like, must always be mounted on a non-combustible insulating base, their contact surfaces kept bright and movable parts examined at least once a day.
All switches must be quick in action and arranged to simultaneously make or break at both poles—connections and rubbing contacts are to be preferred.
Arc lamps should never be employed in factories where there Is fine dust, as from flour, pulverized cork or similar substances floating in the atmosphere.
The frames and other exposed parts of arc lamps should be properly insulated from the circuit. Each lamp must be provided with a proper hand switch; and wherever it is possible that an excessive current may be thrown on to any one lamp or scries of lamps, automatic shunts or switches must be provided for each lamp to prevent all possibility of the forming of a dangerous arc.
Arc lamps should be provided’with means to prevent the carbons from falling out should the clamps fail to hold them.
Arc lamps must have globes closed at the bottom ; and wherever they are placed in proximity to any combustible material, like draperies, goods in show-windows, flyings in fabric factories, or in woodworking establishments, they must be provided with very high globes or spark arresters, and the globes be surrounded by wire netting, to prevent the falling of a broken globe. Broken globes must be replaced at once.
Incandescent lamps should in all cases be mounted in sockets which effectually conceal the terminal connections. Safety plugs will not be allowed in lampholders.
No dynamo or other source of electricity or motor shall be placed in any room of any cotton, woolen, flax, jute or flour mill or similar mill of like description, excepting in the engine-room thereof; and where it is necessary to locate a dynamo or other source of electrical energy or motor in a dangerous position, such generators or motor must in all case be housed, and special permission must in all such cases first be obtained.
Dynamos, generators and motors in all cases should be placed on dry foundation, and preferably raised from the floor by means of insulating skids. They should be kept free from accumulations of oil and dust. A main switch should be placed at or near the dynamo or motor.
Dynamo electric machines should in all cases be provided with an automatic governing device capable of controlling any change in the current.
Storage cells should in all cases be arranged with a space of one inch between the cells, on insulating supports and in a dry place, a metal tank or tank lined with metal placed under them to catch any leakage. They should be kept free from moisture and dust, and preferably should be enclosed in a box provided with holes for the escape of gas.
Fusible safety strips should be located in the leads conveying the charging current to the storage battery, and in circuit from storage battery to translating devices. Switches should likewise be placed in both circuits. Magnetic cut-outs may be employed in place of fusible strips.
All circuits shall be tested at least twice a day with some approved apparatus designed for that purpose, in order to discover any ground connection or escape that may exist. A record of these tests shall be entered in a book provided for this purpose and a transcript thereof furnished to the proper authorities once a week.
Where secondary generators or transformers are employed, they should preferably be located exterior to the building in a specially prepared fireproof structure, which should be perfectly dry. Where necessity requires that they be within the building, they should be housed in a dry wooden room lined with asbestos board—a cut-out should be included in the primary circuit, adapted to act at any increase of twenty-five per cent above normal current. A warning or danger sign should be placed upon door of such housing. When electric light or power circuits are intended to be constructed, full particnlars of the proposed installations and all its details must be given in writing to the proper authorities. This must be accompanied by samples of the conductors with a statement of the maximum current which it is designed to send through each. Samples of the cut-outs, switches, fusible plugs should likewise be submitted unless they have previously been approved. The signing of these rules and regulations by any electric lighting, power or other company transmitting electric currents, shall be considered as a guarantee on their part that they will faithfully observe all the conditions and make such reports as are therein provided.
II.-RULES TO BE OBSERVED IN LOCATING AND CONSTRUCTING AERIAL AND UNDERGROUND CONDUCTORS.
Conductors conveying currents, having an E. M. F. of over fifty volts, where carried through cities or closely settled localities, should in all cases be insulated.
Conducting wires over buildings must be located at least seven feet above the roofs, and also high enough to avoid the ladders of the fire department.
Conductors conveying currents for arc light or power, secondary distribution or the like, and when run parallel with telegraph or telephonic conductors, should in no case be nearer than ten feel where single, and six feet where double. By double is meant outgoing and return leads.
Conducting wires must be secured to insulating fastenings and covered with an insulation which is water-proof on the outside and not easily worn by abrasion ; and where wires are passed through walls, cornices or the like, should be protected as in the rule.
Conductors carried along the exterior walls of buildings should in all cases be supported upon glass insulators, placed at least ten inches apart and so arranged as to be liable to abrasion from cornices, metallic shutters and the like. Special means should be provided to prevent accumulations of ice upon such conductors.
Conducting wires conveying currents, such as employed in electric lighting and power, and which are in proximity to other wires, should be so secured or guarded as to prevent any possibility of contacts between the wires in case of accidents to the wires or their supports.
All conductors carried underground should be encased in lead and preferably located in conduits made of a material which is non-porous to gas or water, non-inflammable and of good insulating character.
III.-RULES TO BE OBSERVED TO PREVENT ACCIDENTS TO LIFE.
No work of any sort, kind or description should be done upon an electric circuit whereon the E. M. F. of the current flowing exceeds fifty volts for alternating currents and 200 volts for continuous currents.
Where it is necessary to repair any portion of the line or fixtures, or lamps or other translating devices contained therein or thereon, and the current be flowing thereon, such portion of the line or fixture must first be cut out of circuit by means of a suitable cut-out, which shall be in electrical connection with a visual or audible tell-tale device, to show or make evident by sound that no current is flowing on the line.
Where bare conductors are employed for the transmission of power, they should rest upon insulating supports, and be provided with an insulating covering for at least two feet each side of the support.
Long lines having a number of arc lights in series should be provided with a shunt and suitable cut-out switch around every five lamps.