A
LIGHTNING PROTECTION AND GROUNDING
Page T-1
Repair and Service Manual
Read all of Section B and this section before attempting any procedure. Pay particular attention to all Notices, Cautions, Dangers and Warnings.
GS-726-006
EFFECTIVE:
10/19/92
REVISION:
SUPERCEDES:
Rev -, ECN 027194
TITLE :
General Specification: Lightning Protection and Grounding
1. Grounding Requirements
For the purpose of this specification, building ground systems should serve two primary functions: personal safety and
equipment protection. In order to be effective, all elements and functions of building ground system must receive equal
consideration in design and installation. Once installed, it is up to the owner to adequately maintain the system by imple-
menting periodic inspections and ground tests in order to determine its effectiveness.
2. Ground Systems
All electronic equipment is inherently related to earth by capacitive coupling, accidental or incidental contact and inten-
tional connection. The earth forms a natural readily available form of common potential reference for all electrical circuits.
For maximum effectiveness, grounding must be looked at from a total system viewpoint, with various sub-systems com-
prising the total facility ground system. The interconnection of the various sub-systems into a building ground system will
provide a direct path, of known low impedance, between earth and the various electrical and other equipment. This effec-
tively extends an approximation of ground reference throughout the building. The total building ground system is com-
posed of an earth electrode system, a lightning protection system and an equipment fault protective system.
Resistance To Earth: The resistance to earth of the ground system should not exceed 10 ohms. Where the resistance of
10 ohms cannot be obtained due to high soil resistivity, rock formations or other abnormal conditions, alternate methods
for reducing the resistance to earth must be considered.
Chemical Treatments: No salt, coke or other chemicals may be used to treat the soil in order to obtain the required
ground resistance readings. Approved methods of enhancement are bentonite clay or the GEM product for ground
enhancement as manufactured by Erico Products of Solon, Ohio.
Ground Tests: The resistance to earth of the ground system shall be measured by the “Fall of Potential Method”. Accept-
able resistance meters/testers are those manufactured by Biddle or AEMC.
3. Lightning Protection Requirements
The external lightning protection system shall be designed and installed by a contractor who specializes in the lightning
protection field. The contractor must be listed with Underwriters Laboratories Inc. and be in good standing. All work shall
be under the direct supervision of a Certified Master Installer with current credentials from the Lightning Protection Insti-
tute.
The materials and design for the structure will comply with the most recent edition of the National Fire Protection Associ-
ation Lightning Protection Code, NFPA 780 and the Materials Standard for Safety from Underwriters Laboratories UL96.
Materials for this project may be those of Harger Lightning Protection, 1066 Campus Drive, Mundelein, Illinois (800-842-
7437).
Upon completion of the project, the contractor will supply to the owner the Master Label issued by Underwriters Labora-
tories.
4. Equipment Fault and Personal Safety System
The standard method of providing an equipment fault protection ground network is to run a good ground conductor
(green wire) through the conduit together with the AC distribution system. This method is required for all types of conduit,
including metallic.
5. Ground Network Requirements
Install the conduit in accordance with local regulations or as prescribed by the National Electrical Code.
