UFC 3-460-03
21 JANUARY 2003
9.5.5. Truck Fill Stand Grounding Assembly.
9.5.5.1. The assembly modification to the truck fill stand is done by the BCE from local resources,
along with the FMF. Funding for materials is available from DESC. Visit the DESC home page at
9.5.5.2. The grounding assembly is installed and must be attached to a permanent structure of the
fill stand, readily available for the refueler operator, and must be electrically interconnected to an
existing approved static ground. The fixture uses the standard grounding hardware already
installed on the refueler's reel cables. The design provides extra features that make the receptacles
available from either direction of entry, and automatically disconnects if the vehicle is accidentally
driven off; it also includes additional receptacles in case of a jack failure.
9.5.5.3. The aluminum T-bar may be attached to any type of surface (painted or bare metal) with
standard cadmium-plated nuts and bolts. A number 10 or larger solid copper wire should
interconnect with the assembly lug and approved static ground. Galvanic corrosion between two
different types of metals will be minimal and have little effect on the assembly.
9.5.6. Hydrant Fueling Systems.
9.5.6.1. Where hydrant systems are grounded, it may be convenient to use a galvanized steel
combination ground rod tie-down anchor (at least 16 millimeters [0.625 inch] in diameter by
2.4 meters [8 feet] in length) that is convenient to the aircraft. For Type II systems, it is centered
between the hydrant outlet box and the electrical junction box paving. The surface of the paving
should be cupped out to provide accessibility.
9.5.6.2. Provide a standard electrical ground clip on one end of the grounding cable. This
connecting fitting should provide positive gripping by the clip's teeth only, so that it must be
opened to be removed.
9.5.6.3. Some Type II and III systems permanently bond the piping at the hydrant outlet to a
driven ground rod (Type II systems also bond to the electric conduit at the electrical junction-
receptacle box) with 1/0 copper bonding cable and approved grounding clamps. Usually, cathodic
protection is applied to the hydrant system underground piping to retard corrosion. When the
hydrant outlet is bonded to a ground rod, the outlet must be electrically isolated from the
cathodically protected piping system at the first pair of flanges below the outlet. This is required
to prevent shorting of the cathodic protection system, thereby making it ineffective. NOTE:
Where cathodic protection is installed, and the hydrant outlet valve is grounded, it is extremely
important to periodically verify the integrity of the isolation flange.
9.5.6.4. Use at least 15.8 millimeters [0.625 inch] in diameter by 2.4 meters [8 feet] in length
galvanized steel rods with tie-down rings (or Shepherd's hooks), for static grounds. For bare base
and remote locations, use ground rod NSN 5975-00-240-3859.
9.5.6.5. Resistance of an approved static ground may be as high as 10,000 ohms, although a lower
resistance is usually experienced.
9.6. Electrical Currents. Electrical currents originate in generators, transmission systems, wiring, and
electrical devices. They are more dangerous than static charges because of the continuous electrical
spark compared with the brief spark of a static charge. Observe the following precautions to eliminate
the hazard of electrical currents. Verify that all electrical work on petroleum storage and dispensing
systems complies with the NEC for Class I liquids. This is required by NFPA 407 2-4.9, Standard for
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