Rockwell Automation Publication 2100-IN012G-EN-P - August 2016 91
Final Checklist Before Energizing Chapter 7
Required Minimum Electrical
Spacing
.
Table 7 - Electrical Spacing Requirements for MCCs
(1)
(1) An isolated dead metal part, such as a screw head or a washer, interposed between uninsulated parts of opposite polarity or
between an uninsulated live part and grounded dead metal, is considered to reduce the spacing by an amount equal to the
dimension of the interposed part along the path of measurement.
Voltage
Min Spacing, in. (mm)
Between Live Parts of Opposite Polarity Between Live Parts and
Grounded Metal Parts, Through
Air and Over SurfaceThrough Air Over Surface
0…150 0.5 in. (12.7 mm) 0.75 in. (19.1 mm) 0.5 in. (12.7 mm)
151…300 0.75 in. (19.1 mm) 1.25 in. (31.8 mm) 0.5 in. (12.7 mm)
301…600 1.0 in. (25.4 mm) 2.0 in. (50.8 mm) 1.0 in. (25.4 mm)
(2)
(2) A through-air spacing of not less than 0.5 in. (12.7 mm) is acceptable.
at a circuit-breaker or fusible disconnecting means
between grounded dead metal and the neutral of a 3-phase, 4-wire motor control center
601…1000
(3)
(3) Applies only to rectified output >600V DC.
1.5 in. (38 mm) 2.5 in. (63 mm)
(4)
(4) Through-air spacing required is 1.5 in. (38 mm); over-surface spacing required is 2.0 in. (50 mm).
Table 8 - Spacing Requirements within MCC Units
Voltage
Min Spacing, in. (mm)
Between Uninsulated Live Parts of Opposite
Polarity and Between an Uninsulated Live
Part and an Exposed or Uninsulated Dead
Metal Part other than the Enclosure
Between Uninsulated Live Parts and
the Walls of a Metal Enclosure
(1)
,
Including Fittings for Conduit or
Armored Cable
(1) The enclosure refers to the section enclosure.
Through Air Over Surface Shortest Distance
0…150 0.125 in. (3.2 mm)
(2)
(2) The spacing between wiring terminals of opposite polarity shall not be less than 0.25 in. (6.4 mm) if the terminals are in the
same plane. A metal piece attached to the enclosure shall be considered to be a part of the enclosure for the purpose of this
note if deformation of the enclosure is likely to reduce the spacing between the metal piece and a live part.
0.25 in. (6.4 mm) 0.5 in. (12.7 mm)
151…300 0.25 in. (6.4 mm) 0.375 in. (9.5 mm) 0.5 in. (12.7 mm)
301…600 0.375 in. (9.5 mm) 0.5 in. (12.7 mm) 0.5 in. (12.7 mm)
601…1000
(3)
(3) DC circuits derived from rectified AC circuits without increases to the peak nominal voltage can comply with the electrical
spacings of the AC supply voltage.
0.55 in. (14 mm) 0.85 in (21.6 mm)
(4)
(4) Through-air spacing required is 0.8 in. (20.3 mm); over-surface spacing required is 1.0 in. (25.4 mm).
To Next Page
Need help?
General
