Cut Sheet

10
Technical Data TD01701001E
Effective March 2017
UL low-voltage busway
Pow-R-Way III
EATON www.eaton.com
Electrical data (continued)
Housing ground vs. internal ground
Eaton’s Pow-R-Way III busway offers a variety of grounding
options. Two of which are 50% integral housing ground and
50% internal ground.
The 50% internal ground option has a separate ground conductor
internal to the housing, which is rated 50% of the phase conductor.
The integral housing ground is where the extruded aluminum housing
is used as the ground path and no internal ground conductor is
provided. The housing is UL Listed as a 50% integral ground path.
This type of ground path is as effective as a ground conductor as an
internal ground bar. Table 12 shows a cross-sectional comparison
between the aluminum housing and internal ground bar. The integral
housing ground provides a larger ground path that is over 100%
of the cross-sectional area of the phase conductors. Figure 13
illustrates the difference between the two grounding options.
Table 12. Housing ground vs. Internal ground comparison
UL 857 ampere rating
Bar size (in)
Bar per
phase
Cross-sectional area
(sq in)
Internal
ground
Housing
groundCu Al
225 225 0.13 x 1.63 1 0.20 2.37
400 400 0.13 x 1.63 1 0.20 2.48
600 600 0.13 x 1.63 1 0.20 2.48
800 — 0.13 x 1.63 1 0.20 2.48
1000 — 0.13 x 2.25 1 0.28 2.54
1200 800 0.13 x 2.75 1 0.34 2.69
1350 1000 0.13 x 3.25 1 0.41 2.83
1600 1200 0.13 x 4.25 1 0.53 3.11
2000 1350 0.13 x 5.50 1 0.69 3.46
— 1600 0.13 x 6.25 1 0.78 3.68
2500 2000 0.13 x 8.00 1 1.00 4.17
3200 — 0.13 x 4.25 2 1.06 6.22
4000 2500 0.13 x 5.50 2 1.38 6.92
— 3200 0.13 x 6.25 2 1.56 7.36
5000 4000 0.13 x 8.00 2 2.00 8.34
Integral Housing Ground
Internal Ground Bar
Figure 13. Housing ground vs. internal ground