ERICO Practical Guide to Electrical Grounding - Manual (Page 44)

36 Practical Guide to Electrical Grounding
Fig. 2-22
Downleads following steel members must be
bonded to the steel at the upper and lower
extremities and at 200 foot maximum intervals.
Fig. 2-23
A dead end conductor must be no longer than 16
feet. If over 16 feet, a second conductor path must
be added.
Bond To Steel
200 Foot MaxT
Tall Structural Steel Building
40'
16'
LIGHTNING SAFETY ANALYSIS
It is recommended that a lightning safety analysis be made
of facilities and areas subject to lightning. Following are
parameters to consider and recommendations:
1. Make a physical inspection. Identify hazards and
threats which will contribute to lightning danger at
the site.
2. Make a study of lightning strike probability.
Review the five-year actual strike data from
archives. Estimate the probable future annual strike
density within 1 square km.
3. Do a grounding analysis. Measure existing grounds
(ohms). Do a soil analysis (ohms-m).
Determine type and amount of additional
grounding needed to meet desired resistance.
Establish an inspection / maintenance protocol.
4. Evaluate the existing air terminal / down conductor
/ bonding / shielding. Evaluate all appropriated
designs and options. Establish an inspection /
maintenance protocol.
5. Consider surge suppression devices. Make a study
of the electrical signature of the facility. Identify
vulnerabilities. Identify signal / energy protection
options. Recommend detailed Fortress Concept
protection.
6. Perimeter review. Identify “safe / not safe” zones or
areas for personnel. Identify potential DC,
Capacitive and inductive coupling to critical and
non-critical areas. Recommend “best available”
shelter options.
7. Lightning detection and personnel notification.
Develop criteria for cessation of activities.
Recommend appropriate lightning detection and
signaling devices. Integrate decisions into overall
Facility Safety Plan.
8. Implement recommendations. Certify correct
installation of all safety devices. Create appropriate
safety signage, brochures, literature, posters and
text relating to the lightning plan at the facility.
Prepare affidavit indicating that the facility uses
“best available technology” for lightning safety.
(From National Lightning Safety Institute.)
Grounding Book 4/14/99 10/5/99 6:01 PM Page 36 (Black plate)