The National Electrical Code was originally drawn in 1897 as the result of the united efforts of the various Insurance, Electrical, Architectural and allied interests which through the National Conference on Standard Electrical Rules, composed of delegates from various National Associations, unanimously voted to recommend it to their respective associations for approval or adoption; and is here presented by the National Board of Fire Underwriters with the various amendments and additions which have been made since that time by them.
The following is a list of the Associations composing the National Conference on Standard Electrical Rules:—
American Institute of Architects. American Institute of Electrical Engineers. American Society of Mechanical Engineers. American Institute of Mining Engineers. American Street and Interurban Railway Association. Associated Factory Mutual Fire Ins. Co's. Association of Edison Illuminating Companies. International Association of Municipal Electricians. National Board of Fire Underwriters. National Electric Light Association. National Electrical Contractors' Association. Underwriters' National Electric Association.
TO CONTRACTORS
This volume contains only the installation rules under Classes A, B, C and E, such as are required by the contractor "on the job," and is for general distribution. Another volume is issued in a small edition containing requirements for the construction of approved devices and materials (Class D), and rules for Marine Wiring (Class F). This second volume will not be furnished for general distribution, as the semi-annual List of Approved Fittings will give the contractor all the information as to approved devices which he may need.
GENERAL PLAN
GOVERNING THE ARRANGEMENT OF RULES
CLASS A.—STATIONS AND DYNAMO ROOMS. Includes Central Stations; Dynamo, Motor, and Storage-Battery Rooms; Transformer Sub-stations, etc. Rules 1 to 11.
CLASS B.—OUTSIDE WORK, all systems and voltages. Rules 12 to 13 A.
CLASS C.-INSIDE WORK :— General Rules, all systems and voltages. Rules 14 to 17. Constant-Current Systems. Rules 18 to 20. Constant-Potential Systems :— General Rules, all voltages. Rules 21 to 23. Low-Potential Systems, 550 volts or less. Rules 24 to 34. High-Potential Systems, 550 to 3,500 volts. Rules 35 to 37. Extra-High-Potential Systems, over 3,500 volts. Rules 38 and 39.
CLASS D.—FITTINGS, MATERIALS, AND DETAILS OF CONSTRUCTION, all systems and voltages. Rules 40 to 63.
NOTE.—Class D is omitted from this pamphlet.
CLASS E.—MISCELLANEOUS. Rules 64 to 67.
CLASS F.—MARINE WORK. Rules 68 to 83.
NOTE.—Class F is omitted from this pamphlet.
GENERAL SUGGESTIONS.
The following as well as the fine print notes in the rules are simply suggestions and explanations and are in no case to be considered by inspection departments as mandatory.
In all electric work, conductors, however well insulated, should always be treated as bare, to the end that under no conditions, existing or likely to exist, can a ground or short circuit occur, and so that all leakage from conductor to conductor, or between conductor and ground, may be reduced to the minimum.
In all wiring special attention must be paid to the mechanical execution of the work. Careful and neat running, connecting, soldering, taping of conductors, and securing and attaching of fittings, are specially conducive to security and efficiency, and are strongly advised.
In laying out an installation, except for constant-current systems, every reasonable effort should be made to secure distribution centers located in easily accessible places, at which points the cut-outs and switches controlling the several branch circuits can be grouped for convenience and safety of operation. The load should be divided as evenly as possible among the branches, and all complicated and unnecessary wiring avoided.
The use of wire-ways for rendering concealed wiring permanently accessible is most heartily endorsed and recommended; and this method of accessible concealed construction is advised for general use.
Architects are urged, when drawing plans and specifications, to make provision for the channeling and pocketing of buildings for electric light or power wires, and also for telephone, district messenger and other signaling system wiring.