Rockwell Automation 2100 CENTERLINE Low Voltage Motor Control Centers - Manual (Page 85)

Rockwell Automation Publication 2100-IN012E-EN-P - February 2012 85
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
Surface Through 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 may 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).