Grounding Question

Maybe this?

99NEC 250-64. Grounding Electrode Conductor Installation. (e) Enclosures for Grounding Electrode Conductors. Metal enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode, and shall be securely fastened to the ground clamp or fitting. Metal enclosures that are not physically continuous from cabinet or equipment to the grounding electrode shall be made electrically continuous by bonding each end to the grounding conductor. Where a raceway is used as protection for a grounding conductor, the installation shall comply with the requirements of the appropriate raceway article.

The IAEI SOARES BOOK ON GROUNDING explains the need very well, with some actual field tests.

Thanks for the reply post, the book you refence is this available ON LINE

Info through

Suggestions:
1. Visit
for NFPA 70-1999 National Electrical Code
2. Also,
IEEE Std 142-1991 "IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems"
Section 2.2.6 Bonding of Metal Sleeves Enclosing a Grounding Conductor supplements the NFPA 70 by good explanations, e.g. Figure 33 Bonding of Metal Enclosure, and L x di/dt, or Xl x Iac, etc.