2010 Construction and Material Specifications - Ohio Department of ...

825
733.03
l. Terminal Blocks. Furnish cabinets that include terminal blocks
mounted on panels on the walls of the cabinet. Ensure that the blocks are not
obstructed by shelf-mounted devices. Furnish sufficient terminal sets for each
individual harness wire as well as for contacts of signal load switches, flasher
transfer relays, flasher, and other components. Also, provide separate terminal sets
for field wiring connections, including power, signal, interconnection, and detector
lead-in cables. Group terminal sets to separate higher voltage (120 VAC) from
lower voltage, and arrange them into logical groups. Protect terminal blocks from
accidental contact during the installation and removal of shelf-mounted equipment.
Locate the blocks no closer than 4 inches (100 mm) from the bottom of pole and
pedestal mounted cabinets, and no closer than 6 inches (150 mm) from the bottom
of foundation mounted cabinets.
Ensure that the terminal points are UL listed as suitable to carry the
rated loading. Ensure that the capacity and size of the terminals are as specified in
NEMA TS-1, Section 10.2.5. Ensure that the terminal points for signal field
wiring for each circuit accommodates at least four 12 AWG conductors with spade
type terminals.
Furnish terminal points for incoming power wiring that accepts either
spade terminals or bare stranded wire and are suitable for either aluminum or
copper conductors.
Space terminal sets for easy wiring. Furnish at least six reserve
terminal sets for controllers. Harnesses may terminate on the back of terminal
blocks using through-panel terminals. Clearly mark terminal sets for ready
identification including through-panel terminals that are identified on both sides.
Ensure that the contact between adjacent terminal points are made by bus bar, or
by wire jumpers having spade type terminals securely attached to each end.
m. Terminal Buses. Furnish a cabinet with supply terminal buses
fed from the line side of the incoming 120 VAC power line, after the phase wire
has passed through the main power switch. Ensure that the requirements for use of
radio interference filters are according to Item 8 of this Section, with the buses
supplying load switches and with flashers being filtered when required. Ensure
that a signal bus relay controls power to the bus supplying power for the signal
load switches. . The following overrides NEMA requirements for signal bus
relays. A solid-state relay shall be used for the signal bus relay. The signal bus
relay shall maintain output equal to or above the rating of the cabinet main
overcurrent protection device over the NEMA TS-2 Environmental Operating
Range of -50 to +185 degrees F (-45 to +85 degrees C).
Furnish a common terminal bus for the connection of the neutral
wire of the incoming 120 VAC power line. Ensure that the common bus has
sufficient terminal points to accommodate all potential cabinet wiring as well as
field wiring. Use a separate common terminal, insulated from the panel, for the
interconnect common.
Furnish bus terminal points that comply with Item 12 of this
Section for conductor accommodation, attachment and identification.