and this practice will apply to joint poles. Originally we had the bottom, metal pole step seven feet four inches above the ground with two or three wooden steps in between. We are now eliminating the

wooden steps.

E. R. NORTH MORE: Our specification between

poles is seven feet and a half. We have about 200,000 joint poles in California at the present time.

THE CHAIRMAN: The next item on the program is the report of the Inductive Interference Committee, M. A. E. Silver, Chairman.

Work

The report for this year of the Inductive Interference Committee will be primarily one of progress only. The essential effort has been directed toward organizing the active work, acquiring increased knowledge of the situation generally and dealing with specific problems of immediate concern. None of the work undertaken, other than that of a current advisory nature, has been completed sufficiently to warrant publication of results as a finished product.

The initial year's work of the Committee as described in the report presented at the last annual Convention at Pasadena in May, 1920, embraced three essential features, in brief, as follows:

(1) Appraisal of the general inductive interference situation, bringing out the steadily increasing seriousness of inductive interference due to increasing opportunity for its occurrence with the growth and development of the line systems of both power and communication utilities, the necessity of these services to the public, the lack of broad and intelligent planning in the coordination of these services in the public interest, and the lack of systematic procedure among the power companies for investigating and treating inductive interference problems.

(2) The recommendation for a headquarters staff as a means for providing centralized expert facilities for undertaking needed investigations, directing general procedure and effecting community of effort.

(3) The acceptance of these recommendations by the executives of the Association and the authorization to proceed along the lines advocated.

The work this year has proceeded along the lines of these recommendations, and has in the main served to substantiate the Committee's findings of last year. Fortunately, as the Headquarters Engineering Department was established essentially at the beginning of the association year, and also coincidently with the start of the active inductive interference work, the routine of this active work has readily developed around the headquarters staff, as desired.

The development of the work, in all its phases, has been facilitated by the advice and assistance of Mr. Frank F. Fowle, who was retained at the beginning of the association year as a consulting expert on inductive interference.

As the work of the Committee has developed, and

particularly since the establishing of the Engineering Department at headquarters and its active participation, there has been increasing occasion to deal with problems involving public policy and other considerations outside the strictly technical sphere. Good examples of this are the calls for aid in regulatory commission cases and for advice in the question of division of expense of mitigation measures. Owing to this condition the Committee has given particular care to keeping Association executives and the Public Policy Committee acquainted with the problems being encountered and the procedure being followed. This course has brought very helpful advice and support.

Headquarters Activities

Mr. W. J. Canada, as Director of Engineering of the Association, has been active in organizing and developing the inductive interference work at Headquarters. In addition to several new lines of work which Mr. Canada has initiated, the Engineering Department has also taken over the direct handling of several of the activities which were started by the Committee last year. Principal among these

are:

The routine handling of specific inductive interference cases through the rendering of advice or assistance to member companies.

The keeping in touch with public inductive interference problems, such as those before regulatory commissions, to aid toward the establishment of sound practices and procedure.

The gathering and compiling of technical and legal data on inductive interference. The work at headquarters has been carried along in close cooperation with the Committee.

The inductive interference work carried on by the Engineering Department is described more completely in a section of this report appearing below. Subcommittee Activities

In view of the taking over by the Engineering Department at the beginning of the year of certain. of the inductive interference work, it was found desirable to effect changes in the organization of subcommittees. The work of last year's Subcommittee on History, Bibliography and Data was taken over in its entirety, while that of the Subcommittee on Current Problems was taken over except as regards the cooperative work with the A.I.E.E. Subcommittee on Wave Shape in its effort to develop the limiting value for the A.I.E.E. telephone interference factor of a wave rule.

To continue this latter work a new subcommittee

was appointed on Telephone Interference Factor Investigations, with Mr. H. B. Gear as chairman. The initial work planned comprised largely field investigations of the related characteristics of apparatus and circuits as a contribution toward the complete representative information desired by the A.I.E.E. Subcommittee. Some delay was experienced in getting the field work under way due to lack of the necessary meters and instruments-some of these not being generally available on the market. These were obtained, however, in time to permit a limited number of tests.

While the results thus far constitute only a start in gathering the complete information needed, the progress has served to bring out a better appreciation of the several other factors than t.i.f. (telephone interference factor of a wave) concerned in causing telephone interference. The tests thus far have lacked opportunity for observing the telephone interference resulting from varying degrees of susceptibility of the telephone circuits under any specific degree of wave distortion in a parallel power circuit. More extensive observation, study and weighing of results will be required before conclusions as to a proper limiting value for t.i.f. can be drawn. In fact, this value cannot properly be fixed except in conjunction with the development of suitable methods of quantitatively measuring the effect of the other interdependent factors. In particular, no suitable method of measuring telephone susceptibility appears at present available.

The work of the Subcommittee on Telephone Interference Factor Investigations is described more completely in a section of this Report appearing below.

The Committee recognizes the general lack of technical knowledge of inductive interference and of methods of its control, particularly as concerns telephone apparatus and telephone susceptibility. For the purpose of undertaking and encouraging studies and research along the needed lines, a Subcommittee on Research was formed with Mr. A. W. Copley as chairman.

This Subcommittee has made a preliminary survey and listed those items that it considered to be most urgent or offering the most promise of beneficial results from investigation.

No considerable specific research work has, as yet, been started, although progress has been made in analyzing the needs of the situation and directing investigations into systematic and effective channels. The Subcommittee has not undertaken to report upon the recent advances in the art.

The work of the Subcommittee on Research is described more completely in a section of this Report appearing below.

Geographic Divisions and Committees

The Committee's activities have been conducted with a view to thorough coordination with the Geographic Divisions and Geographic Inductive Interference Committees as established from time to time under the new organization plan of the Association.

The developing of the Geographic Division organizations has naturally required considerable time. While in a few Divisions it has progressed to the point that Geographic Inductive Interference Committees are functioning, it is only in those localities where similar committees were previously organized and active that definite constructive work has as yet been gotten under way. However, it is evident that substantial progress is being made and that those committees newly formed this year will next year be in a position to participate more actively.

The Committee has aimed to extend encouragement and assistance to these Geographic Inductive Interference Committees, for it has realized that, owing to lack of familiarity and understanding of the subject, it is difficult to make a satisfactory systematic start with the work.

The part which the Geographic Division organizations, particularly the Inductive Interference Čommittees, are expected to take in the inductive interference work will include assistance in the following:

Maintaining the National Staff in contact with individual companies in all localities and conveying to it information of local conditions and local needs, not unmindful of the closely allied nature of the problems of non-member companies; constructively criticizing principles and practices under development by the National Staff; discussing and harmonizing views between individual local companies; educational efforts in bringing an increased understanding of the inductive interference problem to local power men generally; introducing and putting into effect national policies as established; and applying specific treatment to routine inductive interference cases as they arise.

With more geographic committees becoming established and giving regular and systematic attention to the subject, increasing progress will be realized in building up a better working knowledge of inductice interference and in accomplishing the needed coordinated treatment throughout the industry.

Technical Advisory Committee

Primarily for the benefit of the Technical Section as affording to its several committees a source of advice and counsel, the Association has, during the year, established a Technical Advisory Committee. This Advisory Committee, composed of Messrs. A. E. Kennelly, C. F. Scott and Elihu Thompson, all men of the very highest ability and standing in the technical field, brings to these committees a valuable aid in weighing the technical soundness of the fundamental lines of their work.

The Inductive Interference Committee is particularly appreciative of this aid in the undertaking of its various problems because of their complex technical nature and the especial desire that this work be built on a sound and systematically laid technical foundation.

Cooperation with American Telephone and
Telegraph Company

The growing frequency of encountering inductive

interference in meeting the increased demands for both power and telephone service has brought a live appreciation of the need for cooperative treatment of this problem. The desirability of such cooperative procedure has been referred to from time to time in discussions between representatives of the American Telephone & Telegraph Company and various representatives of the power industry. In these discussions the Telephone representatives have expressed a desire for such cooperative procedure and assurance of their willingness to take part whenever the power companies might feel in position for such a move.

The previous lack of a centralized staff on the part of the power companies, contrasted with the thoroughly organized skilled staff of the American Telephone & Telegraph Company, has acted to retard steps for the establishment of channels for joint dealings with these problems on any comprehensive scale.

However, with the Engineering Department established and working with the Committee, joint procedure was believed to be practicable. Accordingly, an expression of the Association's willingness to undertake joint technical inductive interference investigations was communicated, in October, to the American Telephone & Telegraph Company. This expression met with hearty approval and a willing desire for real cooperation.

The plan of procedure under development has in view several purposes directed to accomplishing more satisfactory treatment of inductive interference in its many phases. These include: gaining a better knowledge of the phenomena and means of controlling inductive interference; the systemization and improvement of present coordination practices; the cooperative planning in advance of construction of the coordination of new facilities; better understanding, in the interest of harmonious solutions, of the facts and principles underlying inductive interference practices and the aiding in specific cases to effective

and reasonable solutions.

It is of particular interest that these negotiations aimed at developing joint procedure for dealing with technical problems have progressed hand in hand with other negotiations between executives of the Association and of the American Telephone & Telegraph Company looking to cooperative dealing with broad problems of mutual concern encountered in rendering their respective services to the public.

General and Miscellaneous Aspects

It is believed pertinent to review briefly the present status and some of the recent occurrences of the inductive interference situation. The seriousness of inductive interference, as a broad problem, is increasing in much more than direct ratio with community and industrial growth. Communities and industries are becoming more and more dependent upon power and communication services and the multiplying of the facilities for rendering these services correspondingly multiplies the attention required for their coordination.

This coordination hinges largely around the use of the highways as the logical and intended routes within a community for delivering the various public services to the users. In the past, with a more scattered demand for these services, the avoiding of inductive interference by separation of facilities has been extensively advocated as a general policy by the communication interests, and was for a long time practicable of accomplishment to a varying degree. However, with the increasing community concentration bringing a multiplying of facilities along the highways, the general coordination of different classes of facilities upon the same highway has become a real necessity. This problem of coordination is being somewhat augmented by the present tendency of some telephone companies, previously utilizing leased rights of way along the railroads, to turn to the highways as the leases expire due to changed conditions which make renewal less advantageous to them.

There is need for a clearer understanding of the fallacies of the principle of superior rights by prior occupancy of highways. This principle may react adversely to the public interest in several ways: it encourages careless, low-grade construction on the part of the first comer and the subsequent correction or modernization at the expense of the later comer. It delays the advent of a later service on account of this increased cost and inconvenience and embarrasses the public demanding these later services.

It is evident that the development of a clear understanding of the proper principles governing the coordination of utilities in the use of the highways is of fundamental importance in providing these services to the public with maximum convenience and economy. The legal status of highway usage has in many localities lagged behind commercial and civic advancement and the changing public needs. There is need for a thorough study of present-day demands upon the highways and of the mutual responsibilities and duties among highway users. This is particularly pertinent to the development of satisfactory coordination principles and practices for inductive interference control.

Inductive interference is believed to be the most serious and complex among the forms of conflict encountered between the several public utility facilities. As an index to the importance of inductive interference and of its concern to the public and the power industry, it is helpful to reflect upon the investment involved. United States census figures indicate present investments in power and telephone systems alone aggregating approximately:

Power systems, $3,800,000,000; telephone systems, $1,600,000,000. Allowing for additional investment at a rate reasonable to expect in view of the anticipated heavy future demands for service, particularly power and light service, it is evident that even with only a very small fraction of this money going to meet the inductive interference conflict it will run into many millions of dollars, sufficient to demand very careful study and consideration for reasons of economy alone.

While not overlooking the concern of other interests in the inductive interference situation, the Committee has continued to direct its leading attention to the problems arising with the Bell Telephone and associated interests, for, as pointed out by the Committee in its report last year, this situation has shaped up largely around the developments and practices of the American Telephone & Telegraph Company as the leader in the telephone art.

Due to the complex technical nature of the telephone art and to the fact that its essential development has been accomplished through the efforts of a large highly skilled staff of a single organization, there has not been the necessity for the results of this research work to be generally discussed or made generally available. Furthermore, owing to the valuable scientific devices being evolved and the valuable patent considerations concerned, it is natural that the tendency has been to discourage publicity of engineering details. In fact, the telephone art has been built up with a degree of secrecy not different from that surrounding the development of any important guarded commercial process.

On the other hand, the development of power systems and power apparatus has come about through competitive research and manufacture. The natural tendency of this condition has led to extensive open discussion and a general familiarity with the engineering practices and details. This distinctly greater relative familiarity with the power art has aided the telephone engineers in any open study of inductive interference in restricting the discussions to considerations of and applications to the power systems and in minimizing attention to the telephone systems.

Such an unbalanced viewpoint, even though the natural outcome of conditions as they have existed, is not in the best interest of the public and, besides, places an undue share of the burdens upon the power industry. To do its share in supporting the public interest in addition to protecting its own interest, the power industry must take an active part in planning the policies and practices for the coordination of facilities and the control of inductive interference. Power engineers generally must gain a better understanding of the technicalities of inductive interference and participate more actively in the development of the engineering solutions of current problems.

While the power industry must, and does, recognize that it shares the responsibility and burden incident to the coordination of facilities for the control of inductive interference, it is not willing and it is not proper for it to accept more than its equitable share of this coordination; that is, it is not willing to accept and pass on to the public, through the medium of its rates for service, a share of this expense that should properly be passed to the public by other interests concerned.

Again, to effect an equitable division of this responsibility and expense, the power companies must. acquire a more thorough knowledge of inductive.

interference and take an active part in all these problems affecting the industry.

The year has been characterized by increased activities upon the part of state regulatory commissions in the matter of overhead line regulations, and in this they have given increased attention to the subject of inductive interference. This increased tendency of the commissions to issue rules on inductive interference has been sometimes overlooked on the part of the power companies, resulting in a lack of suitable presentation of their side of the problem and lending to premature regulations.

It is usual for the work of developing regulations of this kind to be carried out in a joint committee, comprising representatives of the different utilities, under the direction of the commission. The power company representatives on these committees frequently do not adequately realize the importance of the work in which they are taking part. Participation with an inadequate knowledge of the subject and without due appreciation of the responsibilities carried lends definite aid to unbalanced rules and illconsidered precedents adverse to the power industry and not in the best interest of the public.

Throughout the year the Bell Telephone Companies have been active in conducting, in the southeast and other parts of the country, inductive interference surveys. This work is understood to be a part of a nation-wide survey started somewhat earlier. These surveys comprise the gathering of thoroughly comprehensive information, including the mapping of all essential power lines and telephone lines. The survey also includes the gathering of complete information of the kind, size, arrangement and characteristics of power apparatus and power circuits. When finished it will equip the Bell Companies with complete and dependable records of all power circuits and power system apparatus which may be of concern to the development and operation of their plants. The Committee has encouraged member companies to cooperate by supplying descriptions of their circuits and apparatus in all cases with the assurance that the information will be utilized only for constructive purposes.

These surveys, could they be made thoroughly cooperative and reciprocal, should prove a definite aid in advancing the knowledge of inductive interference and of the methods of its control. Thus far

they have been initiated and carried on entirely by the telephone companies and the essential benefits. therefore accrue to them. therefore accrue to them. The power companies must take an active part in the work if they are to share in these benefits.

Encouragement is lent to the belief that constructive progress is being made toward a better understanding and more far-sighted treatment of inductive interference generally, by the increased study. that is being given the subject. Regulatory commissions are gaining a clearer appreciation of the public needs for various services. This is bringing a growing realization that many of the precedents underlying present regulations were established under conditions far different from those of today.

There is an evident desire to weigh and take properly into account these changed and changing conditions when dealing with inductive interference problems.

Power men generally are exhibiting a growing appreciation of the serious and cumulative effects from allowing the inductive interference situation to develop along the lines of least resistance. With this is coming a realization of the true scope of the problem; that is, that while it requires technical treatment it is, nevertheless, at present more largely a problem of policy and economy for the executives. This is true because the most immediate and urgent need is for a proper foundation of principles and policies around which to build the solutions of the technical features of the problem. The impediment to correct technical solutions caused by a few illfounded regulatory measures cannot be overemphasized, but has been largely overlooked by power men.

This tendency to increased study of the problem is also becoming manifest among others. In particular technical schools are showing an interest and desire to assist in the technical studies to the end of increasing the general knowledge and furthering the general good. Similarly the American Institute of Electrical Engineers, when recently made acquainted with some misuse and misunderstanding that had arisen around certain of its Standardization Rules affecting inductive interference, gave prompt and willing consideration to the matter, and either modified the rules in question or withdrew them for further study. The Institute furthermore extended encouragement for the cooperative study of these rules by the parties concerned, with the aim of jointly recommending any desirable changes.

Needs and Plans for Further Handling

For further handling of the inductive interference situation the Committee recommends continuing along the lines of present activities as recommended last year. This will embrace attention to many features of the situation, including:

(a) Continuing the activities of the Committee and the Engineering Department to carry on the current and development work in solving inductive

interference problems. It must be kept clearly in mind, however, that it is not the purpose to undertake permanently the handling of all routine inductive interference problems for the industry. Obviously, volume alone would make this impossible. It is, on the other hand, the intent to acquire first the necessary working knowledge of inductive interference in its many phases and then to assist in spreading this information to local organizations and member companies with the aim of helping these local bodies to deal effectively with their own problems. In short, it is the aim to direct the industry in its inductive interference problems and to help local organizations and local companies to help themselves.

(b) Continuing the development of the Engineering Department as the active staff to handle all routine matters, such as dealing with current problems, compiling and analyzing technical and legal data, advising with local bodies and member companies in regard to regulatory measures and court proceedings, conducting development studies and researches, participating in consideration of mutual problems with other interests, etc.

(c) Continuing active aid to the establishment of Geographic Division Inductive Interference Committees and the building up of active work on their part to share and support the work of the National Committee.

(d) Promoting advanced planning of the coordination of facilities required for rendering the services needed in any community, to the end that inductive interference may be minimized during initial construction rather than through mitigation measures subsequently applied.

(e) Continuing cooperative procedure with the American Telephone and Telegraph Company for joint study and treatment of specific problems and for joint investigation of general inductive interference problems.

(f) Continuing efforts to promote a better general knowledge of inductive interference and of its relation to the public need with the aim of meeting these needs in such way as best to serve the public interest and protect the interests of the utilities. concerned.

With the establishment at National Electric Light Association Headquarters of the Engineering Department on June 1, 1920, continuously available service on current inductive interference problems began to function. Member companies, formerly forced to negotiate solutions of such problems without sufficient understanding, either of the technical factors or of the equities involved, are now able to get consistent advice and guidance by utilizing this department.

Some of the different classes of problems coming to the Department will be briefly reviewed.

In five states commission rules on inductive interference have been under preparation or revision

this year by committees of utility representatives.

In North Dakota such a committee had been working some months, but failed to get in touch with this Association as to this activity. Their draft of rules submitted last summer was not acceptable to the commission engineer, who thereupon proceeded to redraft them. This caused considerable apprehension among utilities of all kinds, and the assistance of this Department was thereupon sought. The situation was discussed with the telephone and other interests concerned, and a committee representative of all utilities reviewed the newly proposed rules. This committee agreed to propose to the Commission certain changes to make the rules uniform