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 MIL-HDBK-419A
(2) Measure the resistance between the neutral bus and the equipment grounding conductor or
panel frame. A low value of resistance (< 10 ohms) indicates that the neutral may be grounded at some place
other than at the first service disconnect. Grounding of the neutral at places other than at the first service
disconnect violates the MIL-STD-188-124A and the NEC and will result in power current flow through the
equipment ground network.
1.4.9.3 Correction of Deficiencies. The results of the survey should be thoroughly reviewed to determine the
overall impact of correcting the deficiencies. Complete and strict compliance with the requirements of
MIL-STD-188-124A and the NEC is required. However, some corrections could be expensive and not result in
any improvement in the operation of the facility. Some types of deficiencies should be corrected. Presented
below is a listing of violations that could be encountered and possible corrective actions.
a.
Undersized equipment grounding conductor, replace with proper size conductor.
Equipment grounding conductor and/or neutral conductor not routed with phase conductors. Reroute
b.
the grounding and/or neutral conductor to be in the same raceway as the phase conductors.
Equipment is not grounded by means of an equipment grounding conductor meeting the requirements
c.
of 1.4.9.2d(7) or 1.4.9.2d(8) but is grounded by means of its installation (e.g., mounted in a rack). Ground the
equipment by means of a separate green or identified conductor routed with the phase and neutral conductors.
Neutral bus in power panel (other than service entrance) is grounded to the panel frame. Remove
d.
the grounding connection.
A green wire connected to the neutral bus is found to be connected to an equipment chassis and is
e.
supposed to be the equipment conductor. Disconnect the conductor from the neutral bus and reconnect it to the
ground bus or panel frame with UL-approved connectors.
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