TM 10-4930-204-13
2-3. STARTING.
a. Preparation for Starting:
(1) Check suction hose connections between the tanks and the pumping assembly to ensure that they
are properly locked into place.
(2) Bonding and grounding procedures are as follows:
DEATH or serious injury may result if proper grounding procedures
are not followed prior to operating the equipment.
(a) Bonding is the process that equalizes the charge on two unlike objects such as an aircraft and
a refueling nozzle. It is done in order to prevent arcing, in the presence of flammable vapors, as the two objects
are joined.
1
Extend the grounding cable from the ground reel assembly so the plug (if present) can be
inserted into the vehicle receptacle. Otherwise, attach one of the grounding clips to a bare metal surface of the
receiving vehicle. Attach the remaining clip to the grounding rod. Bond before the dust cap or gas tank cap is
removed to prevent a spark occurring when fuel vapor is present. Do not disconnect the bond until refueling is
complete and the gas tank cap and nozzle dust cap are replaced.
(b) Grounding of equipment is a means to provide a conductive path into the ground so a static
charge isn’t trapped on the surface of the equipment where it could discharge as a spark.
1
Insert the grounding rod into the soil to the required depth (refer to table 2-1). Drive the
rod into the soil to reach below the permanent ground moisture level.
2 If the top of the rod is level with the surrounding surface, scoop out an area around the
top to allow attachment of the ground dips to the rod. Attach the clip from the grounding wheel to the exposed
portion of the grounding rod. The refueler and vehicle are now grounded and the refueling process may begin.
Table 2-1. Required Depths for Ground Rods
Type of Soil
Depth of Ground Rod
Coarse ground, cohesionless sands and gravels
6 feet
Inorganic day, claying gravels, gravel-sand-
4 feet
day, claying sands, sandy clay, gravelly clay,
and silty day
Silty gravel, gravel-sand-silt, silty sand, sand,
3 feet
silt, peat, muck, and swamp soil
(c) Methods of Grounding. There is no quick or easy way to test the adequacy of a ground. The
testing procedures (See FM 10-68 Appendix E) are complex and the equipment is bulky and expensive;
therefore, several levels or methods of grounding and bonding are required to meet the various operational
needs of the Army. The three methods/levels are listed in order of preference.
1 Method 1: equipment is grounded to a rod or rods that have measured resistance to
ground equal to or less than 10,000 ohms. Ground the refueling system to this tested ground rod. Bond the
nozzle to the vehicle aircraft. This method is required, unless conditions, as described below, prevent its use.
This method is the only standard of grounding acceptable, without authorization, at any fixed airfield or
refueling point. It is the safest method.
2 Method 2: If equipment is not available to test resistance to ground, use method 2.
Method 2 uses an untested ground - a grounding system based on the knowledge that damp earth will accept
and drain off an electrical charge. Use method 2 when the location, tactical situation, or type of operation
makes it impossible to test ground rods. Ground equipment to a rod or rods driven a specific depth into the
ground depending on the type of soil at the site (see table 2-1). The depth to which the reds must be driven is
determined by the normal depth of permanent ground moisture in the various types of soils. The commander of
the operating unit must authorize the use of method 2. This method is less desirable. Employ method 2 when
impossible to use method 1.
Change 8
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