Rev. 13 November 1, 2016
Page | 77b. The University of Iowa Facilities Management Electrical Distribution Department will provide and install all
15KV switches, electrical metering, main substation transformers, secondary service protectors, to and
including load side cable connectors, and the 15KV cable.
c. The following shall be installed as part of the construction contract and shall be designed by the project
engineer: All 15KV underground ductbank, 15KV raceway within the facility, transformer vault grounding
system, and concrete housekeeping pads for the electrical equipment supplied by the Electrical Distribution
Department.- Raceway Installation
a. Refer to The University of Iowa Design and Construction Services Design Reference
Manual for more information.
b. Exterior ductbank shall consist of 5” polyvinylchloride (PVC) ducts encased in concrete. Red dye shall
be added to the top of the ductbank. Utilize plastic spacers and tie down conduits. Install a #10 solid copper
“fish” line in all ducts and conduits. All conduits shall terminate 2” inside walls with end bells in all primary
manholes. All conduits shall be evenly spaced and aligned with each other.
c. Encasement shall be poured complete and continuous from one manhole to another and from manholes to
buildings. No construction joints in ductbank shall be permitted between manholes. In case unusual
conditions require a construction joint, furnish and install steel conduit for a minimum of 5 feet on either side
of the joint. A civil or structural engineer shall observe all construction joints.
d. Generally, the top of the conc rete enc asement shall be a mini mum of 24” below final grade.
e. Galvanized rigid steel conduits shall be us ed within the facilit y. Use large sweeps in primary ducts and
conduits, where primary lines a re not straight.
f. In ductbank, steel conduits are required ou t of all manholes and buildings for a distance of
approx imately 10 f eet, at all construction joints if conc rete pours are interrupted, and under all city streets.
26 20 00 Low-Voltage Electri cal Transmission26 22 00 Low-Voltage Transformers- Step-down Dry-type Transformers:
a. Transformers shall be factory-assembled, general-purpose, air-cooled, dry-type distribution transformers
of sizes, characteristics, and rate capacities indicated. Primary windings shall have 6 taps; two 2 ½%
increments above full-rated voltage and four 2 ½% increments below full-rated voltage. Insulation shall be
rated at 220 degrees. Temperature rise shall be rated at 80 degrees. Windings shall be aluminum.
Transformers shall have fully-enclosed sheet steel enclosures, NEMA 1 rated for standard interior
installations. Provide NEMA 3R enclosure with weather shields for wet location installations.
b. K-rated transformers for high harmonic load applications shall have an electrostatic shield, additional coil
capacity and double size neutral terminals. - Bus Duct:
a. Bus duct shall be 3 phase, low impedance, copper bus, with insulated ground bus and full size neutral (where
a neutral is required).
b. Joints shall be single bolt type with silver plated contact surface. - Installation:
a. Switchboards, motor control centers, and transformers shall be installed on concrete pads.
b. Provide nameplates for all distribution equipment.