At the request of the Standards Commnittee this paper has been prepared, the object being to present data relative to the carrying capacity of cables, which will be of value to engineers and users of cables. Especial attention is called to Table I (to be explained later) which gives data relative to the overload capacity of cables which have been working at different percentages of the normal carrying capacity. This question comes up frequently, engineers asking what per cent of overload can be applied to different cables. The per cent of such overload must of course depend upon the per cent of normal load at which the cable has been operating for several hours previous to the application of the overload. It is hoped that the formulas presented will be of value to engineers who have to deal with the subject under consideration.The current rating of an electric cable depends entirely-upon allowable heating, and is often more dependent upon or limited by external conditions than upon conditions intrinsic in the cable itself. On account of the extreme variability of these external conditions, the current rating of any given cable may be reduced to a half or a third, or even a small fraction of its normal rating. The time during which a cable may carry any given per cent overload is shorter than the time during which most other electrical apparatus can carry the same per cent overload. The allowable overload for any given duration of time depends simply upon the rate at which the cable will be heated to its limiting temperature. This is much more dependent upon the properties of the cable itself, than is the ultimate carrying capacity. 325

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