Arrester leads that connect the distribution line and ground terminals of arresters to the equipment they protect
contain a small amount of inherent inductance. This inductance causes L(di/dt) voltage drops to appear
across the leads that conduct lightning surge currents. Any voltage drop across an arrester lead will add to
the arrester discharge voltage. This will increase the voltage appearing across the device(s) protected by the
arrester.
The effect of the line-lead length on the protection of the distribution-line insulation is not as significant as
it is with equipment protection. For overhead equipment, the margin is generally very high. Also, line
insulation level is generally much larger than standard equipment BIL. Of course, it is always good practice
to keep arrester distribution line and ground leads as short and straight as possible. Refer to IEEE Std
C62.22-2009 or more information on arrester lead lengths.