Specifications

PIP ELCGL01
November 2002 Electrical Design Criteria
Process Industry Practices Page 17 of 20
11.2.4 All conduit connections to cabinets and junction boxes located outdoors or
in washdown areas shall be made with factory hubs or weather-tight rigid
conduit hubs.
11.2.5 Conduits shall not enter the top of cabinets or junction boxes located
outdoors or in washdown areas. Bottom entry of cabinets or junction boxes
is preferred.
11.2.6 Conduit drains shall be installed at the low point in all conduit systems
entering electrical enclosures installed outdoors. Drainage provision shall be
made in the bottom of all pull boxes, junction boxes, control panels, etc.
11.2.7 Where long conduit runs are installed, a method of support shall be used that
allows for expansion and contraction. Expansion fittings, with bonding
jumpers around the fittings, shall be installed as required.
11.2.8 On fireproofed structures, the design shall permit conduit supports to be
installed before fireproofing and in such a manner that the conduit does not
become imbedded in fireproofing materials.
11.2.9 Conduit used in corrosive areas shall be as specified on the Data Sheet. Any
conduit coatings shall be applied both on the outside and the inside.
11.3 Underground Conduit and Duct Banks
11.3.1 Underground conduit materials shall be as specified on the Data Sheet.
11.3.2 Stub-ups shall be made using rigid galvanized steel conduit elbows and
galvanized fittings as required and shall include an insulated bushing on any
exposed end of the conduit.
11.3.3 Minimum size of underground conduit shall be 1 inch. Acceptable sizes shall
be as identified on the Data Sheet.
11.3.4 All conduit runs installed below grade (except in floor slabs) shall be
encased in a minimum of 3 inches of concrete on all sides. Concrete shall be
3000 psi with a slump of 5 inches and shall conform to ASTM C94. The
concrete shall be either colored throughout or colored at the top of the
encasement. The coloring shall be a shade of red. Reinforced concrete shall
be used for all underground conduits.
11.3.5 The minimum spacing between conduits in underground duct banks shall be
1-1/2 inches.
11.3.6 The minimum depth of concrete encasement for all underground conduits
shall be as specified on the Data Sheet. This depth shall be measured from
grade to the top of the top conduit.
11.3.7 All horizontal bends in underground conduits shall be made using long
radius sweeps.
11.3.8 When duct banks pass through manholes, the duct banks shall slope
downward toward the manholes at a minimum slope of 3 inches per 100 feet.
11.3.9 Unless indicated otherwise on the Data Sheet, a minimum 20% (or not less
than one) spare conduit(s) shall be installed in all underground duct banks.