Specifications

25
Vertical Power Bus
Vertical power bus bars are cylindrical providing optimum contact with the unit plug-in stabs. Vertical power bus bars are
continuously braced by a high strength, non-tracking glass polyester material and sandwiched by a glass filled
polycarbonate molded bus cover isolating the vertical power bus from the other vertical phases and the horizontal power
bus. The standard vertical power bus is a copper tube rated 300 A above and below the horizontal power bus for an
effective 600 A rating. An optional copper rod rated 600 A above and below the horizontal power bus for an effective
1200 A rating is available. The vertical power bus is tin-plated or silver-plated. The plating of the vertical power bus
matches the plating of the horizontal power bus.
Horizontal Neutral Bus
The horizontal neutral bus, when required for four-wire systems, is available and may be located above or below the
horizontal power bus. Connections to the neutral bus are made though neutral connection plates mounted in the
horizontal wireways of various vertical sections or an optional vertical neutral bus located in a 9 in. (228 mm) wide vertical
wireway.
Bracing
Fully rated bus bracing is available at 42, 65 or 100 kA rms symmetrical. Series coordinated bus bracing is also available at
100 kA rms symmetrical. Series coordinated bus bracing, when used with specific current-limiting mains, provides a cost
affective alternative to 100 kA fully rated bus bracing.
Horizontal Ground Bus
The horizontal ground bus is available as unplated copper or tin-plated copper and may be located in the top and/or
bottom horizontal wireway. The horizontal ground bus is available as 0.25 in. x 1 in. (6.35 mm x 25.4 mm) or 0.25 in. x 2 in.
(6.35 mm x 50.8 mm). The 1/4 in. x 1 in. (6.35 mm x 25.4 mm) horizontal ground bus has an effective 500 A continuous
rating and the 1/4 in. x 2 in. (6.35 mm x 50.8 mm) has an effective 900 A continuous rating. The horizontal ground bus has
various sized holes evenly spaced along the length for making ground connections. A pressure type mechanical lug is
mounted on the horizontal ground bus in the incoming line section. An outgoing equipment ground lug can also be
mounted on horizontal ground bus.
Vertical Plug-in Ground Bus
The vertical plug-in ground bus is mechanically connected to the horizontal ground bus forming a complete internal
ground system in each standard vertical section. The vertical plug-in ground bus in combination with the unit ground stab
establishes a first make, last break operation of the ground connection with respect to the power connects.
The 0.1875 in. x 0.750 in. (4.74 mm x 19.05 mm) vertical plug-in ground bus can be:
• zinc plated steel.
• unplated copper.
• tin-plated copper.