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 MIL-HDBK-419A
Table 1-21. Equipment Grounding Conductor Size Requirement
Size
Rating or Setting of Automatic
Overcurrent Device of Equipment
Circuit.
Aluminum or
Copper-Clad
Aluminum
Copper
Wire No.
Amperes
Wire No.
12
15
14
10
20
12
8
30
10
8
40
10
8
60
10
6
8
100
6
4
200
1
400
3
1
600
2/0
0
800
3/0
1000
2/0
4/0
1200
250 MCM
3/0
1600
350 MCM
4/0
2000
250 MCM
400 MCM
(1) Where the equipment grounding conductor is a separate conductor, verify that the conductor is
routed through the same conduit, raceway, etc., as the phase and neutral conductors.
(2) Verify that the equipment grounding path back to the power panel is continuous and that any
insulating finishes in the grounding path have been removed.
(3) Verify that the size of the equipment grounding conductor is at least as large as that listed in
Table l-21 for the overcurrent device serving the equipment.
(4) Verify that the neutral is not connected to the chassis or frame of the equipment. This may be
verified visually or with an ohmmeter.
Isolation of neutral conductor. When it is possible to deenergize a facility, or a portion thereof,
g.
perform the following test:
(1) With the electrical power removed disconnect the facility neutral from ground or in the case
of a portion of the facility (e.g., a power panel) the incoming neutral. See Figure 1-47.
1-110
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