Historical enquiry.

It's an old un.

https://archive.org/details/paper-doi-10_1038_028044b0


Extract...


RULES AND REGULATIONS FOR THE PRE¬ VENTION OF FIRE RISKS ARISING FROM ELECTRIC LIGHTING * 1

'"D'HESE rules and regulations are drawn up for the reduction to a minimum, in the case of electric lighting, of those risks of fire which are inherent in every system of artificial illu¬ mination, and also for the guidance and instruction of those w ho have, or who contemplate having, electric lighting apparatus installed on their premises.

The difficulties that beset the electrical engineer are chiefly internal and invisible, and they can only be effectually guarded against by “ testing,” or probing with electric currents. They depend chiefly on leakage, undue resistance in the conductor, and bad joints, which lead to waste of energy and the dangerous production of heat. These defects can only be detected by mea¬ suring, by means of special apparatus, the currents that are either ordinarily or for the purpose of testing, passed through the circuit. Should wires become perceptibly warmed by the ordinary current, it is an indication that they are too small for the -work they have to do, and that they should be replaced by larger wires. Bare or exposed conductors should always be within visual inspection and as far out of reach as possible, since the accidental falling on to, or the thoughtless placing of other conducting bodies upon such conductors, would lead to “ short circuiting,” and the consequent sudden generation of heat due to an increased current in conductors not adapted to carry it with safety.


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The necessity cannot be too strongly urged for guarding against the presence of moisture and the use of “earth” as part of the circuit. Moisture leads to loss of current and to the destruction of the conductor by electrolytic corrosion, and the injudicious use of “ earth ” as a part of the circuit tends to magnify every other source of difficulty and danger.

The chief dangers of every new application of electricity arise from ignorance and inexperience on the part of those who supply and fit up the requisite plant.

The greatest element of safety is therefore the employment of skilled and experienced electricians to supervise the work.

I. The Dynamo Machine

1. The dynamo machine should be fixed in a dry place.

2. It should not be exposed to dust or flyings.

3. It should be kept perfectly clean and its bearings well oiled.

4. The insulation of its coils and conductors should be practi¬ cally perfect.

5. All conductors in the dynamo room should be firmly sup¬ ported, well insulated, conveniently arranged for inspection, and marked or numbered,

II. The Wires

6. Every switch or commutator used for turning the current on or off should be constructed so that when it is moved and left it cannot permit of a permanent arc or of heating.

7. Every’part of the circuit should be so determined, that the gauge of wire to be used is properly proportioned to the currents it will have to carry, and all junctions with a smaller conductor should be fitted with a suitable safety fuse or protector, so that

1 Recommended by the Council of the Society of Telegraph Engineers and of Electricians in accordance with the Report of the Committee ap¬ pointed by them on May 11, 1882, to consider the subject. Members of the Committee:—Prof. W. G. Adams, F.R. S-, Sir Charles T. Bright, T. Russell Crampton, R. E. Crompton, W. Crookes, F.R.S., Warren De La Rue, D.C.L., F.R.S., Prof. G C. Foster, F.R.S., Edward Graves, J. E. H. Gordon, Dr. J. Hopkinson, F.R.S., Prof. D. E. Hughes, F.R.S., W. H. Preece, F.R.S., Alexander Siemens, C. E. Spagnoletti, James N. Shool- bred, Augustus Stroh, Sir William Thomson, F.R.S., Lieut.-Col. C. E. Webber, R.E.


and more


ay io, 1883]

NA TURK

45

no portion of the conductor should ever be allowed to attain a temperature exceeding 150° F.

8. Under ordinary circumstances complete metallic circuits should be used ; the employment of gas or water pipes as con¬ ductors for the purpose of completing the circuit should not in any case be allowed,

9. Bare wires passing over the tops of houses should never be less than seven feet clear of any part of the roof, and all wires crossing thoroughfares should invariably be high enough to allow fire-escapes to pass under them.

10. It is most essential that joints should be electrically and mechanically perfect and united by solder.

11. The position of wires when underground should be clearly indicated, and they should be laid down so as to be easily in¬ spected and repaired.

12. All wires used for indoor purposes should be efficiently insulated, either by being covered throughout witn some insu¬ lating medium, or, if bare, by resting on insulated supports.

13. When these wires pass through roofs, floors, walls, or parti¬ tions, or where they cross or are liable to touch metallic masses, like iron girders or pipes, they should be thoroughly protected by suitable additional covering; and where they are liable to abrasion from any cause, or to the depredations of rats or mice, they should be efficiently incased in some hard material.

14. Where indoor wires are put out of sight, as beneath flooring, they should be thoroughly protected from mechanical injury, and their position should be indicated.

N. B.—The value of frequently testing the apparatus and circuits cannot be too strongly urged. The escape of electricity cannot be detected by the sense of smell, as can gas, but it can be detected by apparatus far more certain and delicate. Leakage not only means waste, but in the presence of moisture it means destruction of the conductor and its insulating covering, by electric action.

III. Lamps

15. Arc lamps should always be guarded r-by proper lanterns to prevent danger from falling incandescent pieces of carbon, and from ascending sparks. Their globes should be protected with wire netting.

16. The lanterns, and all parts which are to be handled, should be insulated from the circuit.

IV. Danger to Person

17.. Where bare wire out of doors rests on insulating supports, it should be coated with insulating material, such as india- rubber tape or tube, for at least two feet on each side of the support.

18. To secure persons from danger inside buildings, it is essential so to arrange and protect the conductors and fittings that no one can be exposed to the shocks of alternating currents of a mean electromotive force exceeding 100 volts, or to con¬ tinuous currents of 200 volts.

19. If the difference of potential within any house exceeds 200 volts, the house should be provided with a '‘switch,” so arran


Z.

It's an old un.

https://archive.org/details/paper-doi-10_1038_028044b0


Extract...


RULES AND REGULATIONS FOR THE PRE¬ VENTION OF FIRE RISKS ARISING FROM ELECTRIC LIGHTING * 1

'"D'HESE rules and regulations are drawn up for the reduction to a minimum, in the case of electric lighting, of those risks of fire which are inherent in every system of artificial illu¬ mination, and also for the guidance and instruction of those w ho have, or who contemplate having, electric lighting apparatus installed on their premises.

The difficulties that beset the electrical engineer are chiefly internal and invisible, and they can only be effectually guarded against by “ testing,” or probing with electric currents. They depend chiefly on leakage, undue resistance in the conductor, and bad joints, which lead to waste of energy and the dangerous production of heat. These defects can only be detected by mea¬ suring, by means of special apparatus, the currents that are either ordinarily or for the purpose of testing, passed through the circuit. Should wires become perceptibly warmed by the ordinary current, it is an indication that they are too small for the -work they have to do, and that they should be replaced by larger wires. Bare or exposed conductors should always be within visual inspection and as far out of reach as possible, since the accidental falling on to, or the thoughtless placing of other conducting bodies upon such conductors, would lead to “ short circuiting,” and the consequent sudden generation of heat due to an increased current in conductors not adapted to carry it with safety.


More..


The necessity cannot be too strongly urged for guarding against the presence of moisture and the use of “earth” as part of the circuit. Moisture leads to loss of current and to the destruction of the conductor by electrolytic corrosion, and the injudicious use of “ earth ” as a part of the circuit tends to magnify every other source of difficulty and danger.

The chief dangers of every new application of electricity arise from ignorance and inexperience on the part of those who supply and fit up the requisite plant.

The greatest element of safety is therefore the employment of skilled and experienced electricians to supervise the work.

I. The Dynamo Machine

1. The dynamo machine should be fixed in a dry place.

2. It should not be exposed to dust or flyings.

3. It should be kept perfectly clean and its bearings well oiled.

4. The insulation of its coils and conductors should be practi¬ cally perfect.

5. All conductors in the dynamo room should be firmly sup¬ ported, well insulated, conveniently arranged for inspection, and marked or numbered,

II. The Wires

6. Every switch or commutator used for turning the current on or off should be constructed so that when it is moved and left it cannot permit of a permanent arc or of heating.

7. Every’part of the circuit should be so determined, that the gauge of wire to be used is properly proportioned to the currents it will have to carry, and all junctions with a smaller conductor should be fitted with a suitable safety fuse or protector, so that

1 Recommended by the Council of the Society of Telegraph Engineers and of Electricians in accordance with the Report of the Committee ap¬ pointed by them on May 11, 1882, to consider the subject. Members of the Committee:—Prof. W. G. Adams, F.R. S-, Sir Charles T. Bright, T. Russell Crampton, R. E. Crompton, W. Crookes, F.R.S., Warren De La Rue, D.C.L., F.R.S., Prof. G C. Foster, F.R.S., Edward Graves, J. E. H. Gordon, Dr. J. Hopkinson, F.R.S., Prof. D. E. Hughes, F.R.S., W. H. Preece, F.R.S., Alexander Siemens, C. E. Spagnoletti, James N. Shool- bred, Augustus Stroh, Sir William Thomson, F.R.S., Lieut.-Col. C. E. Webber, R.E.


and more


ay io, 1883]

NA TURK

45

no portion of the conductor should ever be allowed to attain a temperature exceeding 150° F.

8. Under ordinary circumstances complete metallic circuits should be used ; the employment of gas or water pipes as con¬ ductors for the purpose of completing the circuit should not in any case be allowed,

9. Bare wires passing over the tops of houses should never be less than seven feet clear of any part of the roof, and all wires crossing thoroughfares should invariably be high enough to allow fire-escapes to pass under them.

10. It is most essential that joints should be electrically and mechanically perfect and united by solder.

11. The position of wires when underground should be clearly indicated, and they should be laid down so as to be easily in¬ spected and repaired.

12. All wires used for indoor purposes should be efficiently insulated, either by being covered throughout witn some insu¬ lating medium, or, if bare, by resting on insulated supports.

13. When these wires pass through roofs, floors, walls, or parti¬ tions, or where they cross or are liable to touch metallic masses, like iron girders or pipes, they should be thoroughly protected by suitable additional covering; and where they are liable to abrasion from any cause, or to the depredations of rats or mice, they should be efficiently incased in some hard material.

14. Where indoor wires are put out of sight, as beneath flooring, they should be thoroughly protected from mechanical injury, and their position should be indicated.

N. B.—The value of frequently testing the apparatus and circuits cannot be too strongly urged. The escape of electricity cannot be detected by the sense of smell, as can gas, but it can be detected by apparatus far more certain and delicate. Leakage not only means waste, but in the presence of moisture it means destruction of the conductor and its insulating covering, by electric action.

III. Lamps

15. Arc lamps should always be guarded r-by proper lanterns to prevent danger from falling incandescent pieces of carbon, and from ascending sparks. Their globes should be protected with wire netting.

16. The lanterns, and all parts which are to be handled, should be insulated from the circuit.

IV. Danger to Person

17.. Where bare wire out of doors rests on insulating supports, it should be coated with insulating material, such as india- rubber tape or tube, for at least two feet on each side of the support.

18. To secure persons from danger inside buildings, it is essential so to arrange and protect the conductors and fittings that no one can be exposed to the shocks of alternating currents of a mean electromotive force exceeding 100 volts, or to con¬ tinuous currents of 200 volts.

19. If the difference of potential within any house exceeds 200 volts, the house should be provided with a '‘switch,” so arran


Z.