F I G . 1 — R E C O R D OF 9 0 0 0 - V O L T T R A N S M I S S I O N C A B L E F A I L U R E S
On system of Commonwealth Edison Company.
Curve 1—Internal troubles.
Curve 2—External damage.
Curve 3—Total.
Troubles due to lightning; failures on tests and joint troubles excluded.