1.10.4 Construction Guidelines (1-14). The following is a list of additional construction practices which have
proven effective in reducing problems of EMP interference and/or instrumental damage:
Isolate power by using internal motor-generator sources and installing lightning arresters on lines.
Put all external wires in continuous, properly grounded ferrous conduit.
Screen over air-conditioning ducts, where they enter shielded areas, must be peripherally bonded to
Interconnect the steel reinforcing bars in concrete into the shielding and grounding systems for the
Use lightning arresters on power station transformers.
Provide all surge arresters with shortest possible leads.
Ground cable outer shields and insure that the shields are continuous and closed throughout their
Bury power and signal cables in ferrous conduit as deeply as is economically feasible (greater than
0.9 meter (3 feet)) to reduce current surges and to slope wave fronts induced on the cables.
Install transient protective devices (TPD's) on all antennas and other electric lines exposed to the
Educate personnel in proper protection practices; for example, extension cords connected to outside
plugs should not be brought into shielded areas.
k . Bond together and ground all nonelectrical conductors such as elevator cables, metal airducts, and
All conduit penetrations must be peripherally bonded to the shield.
Avoid use of nonconducting lubricants when fastening conduit pipes together.
Ensure that a low resistance circumferential electrical weld exists wherever conduit penetrates the
When closed, the cover should provide peripheral contact with the box.
Either use adequate surge protection on oil-filled transformers and other high voltage gear to
prevent explosions or use only dry transformers inside the shielded enclosure.