Splicing Power Bus in Type 3R Enclosures

DANGER

Hazard of Electric Shock, Explosion, or Arc Flash Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E, NOM-029-STPS-2011, or CSA Z462. This equipment must only be installed and serviced by qualified electrical personnel. Turn off all power supplying this equipment before working on or inside equipment. Always use a properly rated voltage sensing device to confirm power is off. Replace all devices, doors, and covers before turning on power to this equipment. Failure to follow these instructions will result in death or serious injury.

This section describes how to splice the power bus of a Type 3R enclosure (manufactured after February 1998) to the power bus of another Type 3R section. Bus splicing material is not captive if the section is equipped with offset bus. Refer to Splice Offset Horizontal Bus for instructions for splicing offset power bus in Type 3R enclosures.

To splice power bus, follow these steps.

1. Turn off all power supplying this equipment before working on or inside the equipment, and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.

2. Remove the horizontal wireway covers and slide the horizontal bus barriers to gain access to the captive splice connectors (see Wireway Covers Removed and Horizontal Bus Barriers Open). See Appendix A—Removal and Installation of Horizontal Bus Barrier Panels for the steps for removing horizontal bus barriers.

   NOTE: On the integral splice bar assembly, located on the left side of each phase bus, the number of splice bars used on each phase is one greater than the number of main horizontal bus bars. The rear-most splice bar includes captive nuts.

   Wireway Covers Removed and Horizontal Bus Barriers Open

   

3. Remove the two left bolts from each splice assembly. Then loosen, but do not remove, the two right bolts of each splice assembly (see Loosen Bolts). If the bus has optional 85,000 A bus bracing supplied (see 85,000 A Bracing Option), also loosen the center nut of each splice assembly.

   NOTE: Do not remove the two right bolts or the center bolt (if applicable) from the splice assemblies. Doing so will permit spacers to fall from the splice assembly. If this occurs, re-assemble the splice bars and spacers (if applicable) in the proper order before continuing.

   Loosen Bolts

   

   85,000 A Bracing Option

   

4. Slide the splice assembly to the left until the two left holes are in line with the corresponding holes in the horizontal bus in the left section (see Slide the Splice Assembly to the Left).

   Slide the Splice Assembly to the Left

   

5. Re-install the two left bolts through the splice assembly and into the horizontal bus (see Insert the Splice Bolts). Make sure the original conical washers are reinstalled with the concave side facing the splice bus (see Place a Conical Washer Under the Bolt Head).

   Insert the Splice Bolts

   

   Place a Conical Washer Under the Bolt Head

   

6. Torque the splice connection bolts at horizontal bus connections to 31–32 lb-ft (41.87–43.22 N•m). Torque 85 kA support nuts (if applicable) to 68–72 lb-ft (92.2–97.6 N•m). See Torque All Bolts.

   Torque All Bolts

   

7. Repeat Steps 2–6 for all phases and the neutral bus (if supplied).

8. Before energizing the equipment, replace all covers and barriers.