Quantcast Earth Electrode Subsystem - hdbk419a_vol20224

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MIL-HDBK-419A Inspection Procedure.
The procedure outlined below follows the same order as the Survey Form. In some facilities, a different
ordering of the steps may be appropriate; in large facilities, more than one of the areas may be examined
simultaneously. The most important task is not the sequential ordering of the steps, it is rather the accurate
and comprehensive conduct of the survey.
Before beginning the survey, enter the name and description of the facility (or the specific building, structure,
or subsystem being surveyed), its location to include sufficient information to identify the geographical area,
the date of the inspection, and the name of surveyor or survey team leader at the top of the Form. Earth Electrode Subsystem.
Determine the configuration of the earth electrode subsystem for the facility. Sketch the conductor
layout in the space provided in Part I, Section C of the Form or on an attached sheet. Engineering drawings
may be attached in lieu of the sketch. Corrections or additions should be made to the drawings as appropriate.
Identify the type of earth electrode subsystem present, i.e., rods, ring ground, grid, grid with rods, plates,
horizontal radials, utility pipes, etc.  Note all interconnections between the earth electrode subsystem and
other conductors such as water pipes, buried tanks, structural columns, underground guard cables, antenna
counterpoises, and power grounds.
To the extent that information is available, determine the composition (copper, copperclad steel,
steel, solid, hollow, etc.), diameter, and length of ground rods, as well as the size, depth, and composition of
the ring ground. If horizontal rods or ribbons are used, record the dimensions; likewise, record the physical
dimensions and composition of plates, cylinders, or other types of electrodes.
Examine the conductor or conductors used to ground the power system neutral in the first service
disconnecting means (i.e., main power switch or breaker for the facility), the power transformers, or other
elements of the power distribution system to the earth electrode subsystem. Record the size or sizes in Section
B, Part I, of the Form. Using a clamp-on ammeter, measure the ac current in each of these conductors and
record in Part IV, Section C.
Inspect those bonds associated with the earth electrode subsystem carefully for evidence of
looseness, corrosion, electrolysis, and lightning or mechanical damage. (For a more detailed discussion of bond
inspection procedures, see Section Note specific deficiencies in the appropriate blanks in Part II of
the Form.
Make a general classification of the type of soil at the site. If the site possesses unique properties
(e.g., located on a mountain top, in a swamp, on a coral reef), appropriately indicate the unusual features. Also
generally describe the weather conditions existing at the time of the survey, particularly if the earth resistance
measurement described in the next step is performed. If known, indicate how recently rainfall totaling at least
0.01 inch has occurred. Enter the site and weather description in Sections D and F of Part I. Also state if any
soil treatment or enhancement procedures have been utilized.


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