Content on this page supplied with permission from this web site of Jim Lux
The standard rod gap uses two long rods (usually square in cross section, but round can be used) either 1/2 or 5/8" in diameter. The end is cut perpendicular. The tables usually show a rod cross diameter of 1.27 cm, which reflects their British/American origin. Rod gap measurements are typically considered accurate to ±8%, when corrected for humidity, temperature, and density.
The rods may be 15 to 75 cm long and the gap will be from 2 to 200 cm. For impulse measurements, IEC and IEEE recommend horizontal mounting of the rod gap on insulators at 1.5 to 2 times the gap spacing above ground.
Copyright 1998, Jim Lux / rodgap.htm / 8 March 1998 / Back to HV Home / Back to home page / Mail to Jim