Lightning Protection for Instruments

DOE-HDBK-1132-99

Crosstalk may occur when different AC signals are transmitted within the same

cable or adjoining cables. A workable solution to prevent crosstalk is to isolate

the paired circuits by shielding each pair and grounding the shields.

Lightning Protection for Instruments .

4.6

In general, most instruments are located in a structure or building. Lightning

protection for instrumentation begins with the lightning protection system of this

structure or building. To provide adequate lightning protection from a direct or

near lightning strike, a low impedance lightning protection system should be

considered. This low impedance lightning protection system provides a path of

lower resistance to earth ground, thereby providing protection for the instruments

and equipment within the protection/shielded zone.

The lightning protection system should be separate from the building grounding

system.

Another issue to consider when providing lightning protection for instruments is

to ensure the instruments and associated cables contained in the structure or

building would not be exposed to different ground potentials during a lightning

strike. This should be achieved by bonding all conduits, cable trays, and shields

of cables to a single ground reference point. This ground reference point should

be connected to the electrodes of the structure or building grounding system.

Where lightning strikes are more prevalent, other lightning dispersion or

elimination methods should be considered.

Surge protection should be considered for more sensitive instruments and

instrument cable runs between the buildings.

Fiber optic links should be used between sensors located in lightning prone

areas and the associated analyzers/transmitters.

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