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 MIL-HDBK-419A
1.13.2 Lightning Protection Network.
a.
Determine the cone of protection established by the air terminals (or by the mast or overhead
ground wire, if a separately installed system is provided). Locate air terminals on a scaled drawing of the
structure (be sure to include all views). Using the procedures of Section 1.3.2.1, determine if all parts of the
facility are adequately included within the cones of protection established by the air terminals. In deficient
areas, determine what additional measures, if any, need to be taken (Sections 1.3.2.1 and 1.3.2.2 should be
consulted for guidance).
Inspect air terminals for type of materials (Section 1.3.2.1.1), for correct height (Section 1.3.2.1.2),
b.
and proper placement (Section 1.3.2.1).
c.
Inspect roof conductors for proper size and correct choice of materials (Tables l-2 and l-3), proper
routing (Section 1.3.2.2.1), and for proper use of fasteners (Section 1.3.2.3).
d.
Inspect down conductors for proper size and appropriate choice of material (Tables l-2 and l-3).
Verify that the routing of down conductors conforms to the recommendations of Section 1.3.2.2.2. Where
structural steel members are used as down conductors, the recommendations of Section 1.3.2.2.2.1 should be
observed. Inspect fasteners and hardware for accessibility, strength, and corrosion resistance as recommended
by Sections 1.3.2.3 and 1.3.3.8.
Verify that adequate guards are provided (Section 1.3.3.10).
e.
1.13.3 Signal Reference and Fault Protection Subsystems.
a.
Inspect to verify that equipotential planes exist in conformance to Section 1.5.1.1.
b.
In steel frame buildings, verify that the equipotential plane is bonded to the main structural steel
elements. In wooden or masonry buildings inspect to assure that multiple downleads are bonded to the plane.
Insure the red and black signal grounds are bonded to the equipotential plane as outlined in Section 1.6.
c.
Verify that the structural steel elements are bonded at the joints to produce a low resistance
(< 1 milliohm) joint. Review Section 1.5.1 for recommended fastening procedures. Welded joints conforming to
Section 1.7.1 are preferred. Mechanically fastened joints should be carefully cleaned, bolts adequately torqued
(see Table l-5), and proper bond protection supplied. Visually inspect cleaning procedures, perform spot checks
torque measurements, and visually verify that paints and sealants are applied as needed. Perform spot check
measurements of bond resistance at structural joints using the double balanced bridge technique described in
Section 2.2.2.3.1. Where bond resistances greater than 1 milliohm are encountered, require that bond surfaces
be recleaned, bolts retorqued, or supplemental jumpers provided as needed to achieve 1 milliohm.
d.
In non-steel frame or masonry buildings, inspect the installation of the supplemental grounding
network for conformance to the recommendations of Section 1.5.1. In particular, verify that the grounding
cables provide the required 2,000 circular mils per running foot of conductors.
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