Terminal Lugs Low voltage AC wiring Low voltage DC wiring Terminal Blocks

Terminal Lugs

All terminations shall be self-tested after installation by pulling on wire with a moderate force to ensure the integrity of crimped lug or proper insertion in box connector.

When installing stranded wire in lugs or box connectors, contractor shall ensure all strands are properly inserted before crimping or tightening screw.

For all wire sizes #10 AWG and smaller, locking type, insulated fork, compression type lugs shall be used for all wiring terminating on terminal strips with terminal screws. Locking fork lugs shall be sized to match wire size and terminal block screws. All terminal lugs shall be crimped with lug manufacturer’s approved ratcheting type crimping tool.

Low voltage DC wiring

For 24 VDC power, control and instrument signal wiring, terminal lugs shall be used for all stranded wire terminations wherever possible.

When equipment is furnished with terminal blocks or terminal connectors that will not accept lugs, conductors shall terminate directly to the connector without the use of a cable lug.

Resistors, diodes, or MOVs installed external to the terminal blocks must be supplied with its own terminal lugs installed under the same screw as the field wire. Terminal screws may have a maximum of two lugs. If the terminal will not accept a terminal lug, then a terminal block with an integral resistor must be used. 

Low voltage AC wiring

For AC power and control wiring up to and including 600 volts, terminal lugs shall be used for all stranded wire terminations, wherever possible.

When wires #8 AWG and smaller are not terminated on terminal strips or under terminal screws (for example, low horsepower motor terminal boxes or electric heater terminations) copper, compression type one-hole lugs, Burndy YA-L series or equal, shall be used. Lugs shall be bolted together then taped as described in paragraph 5.2.7.

Contractor may use one-hole lugs for wire sizes #6 AWG through #4/0 AWG on copper wire up to and including 600 volts. For wire sizes 250 kcmil and above, use two-hole lugs. All lugs shall be electro-tin plated copper long barrel seamless compression lugs, Ilsco type CLN series, or equal. The lugs shall be crimped with a compatible hydraulic compression tool of the same manufacturer as the lug. Crimping shall be performed from the hole end of the lug toward the cable end. Mechanical screwed cable connectors shall not be used. Whenever equipment has provisions for two-hole drilling, provide the appropriate two-hole lug.

Lugs are not required when equipment is provided without provisions for bolting of lugs (for example, mechanical box connectors of motor control centers or molded case circuit breakers). Connectors shall be torqued according to the equipment manufacturers’ recommendations.

For all #6 AWG and above, flexible, stranded motor leads (supplied with motor) for motors below 600 volts, the contractor shall provide compression connector.

When motor leads are provided with lugs that do not employ fully circular compression barrels (for example, open barrel type with folding flaps), the contractor shall remove the lugs and replace them with compression connectors as described above. If unsure regarding a lug’s acceptability, consult the field representative to determine if furnished lugs are appropriate.

Ring-tongue, insulated, compression-type lugs shall be used for all terminations in current transformer driven circuits.

Quick-disconnect, nylon-insulated terminations shall be used for all pigtailed device terminals when standards apply.

Terminal Blocks

Terminal blocks, for instrumentation, 120VAC power and control shall be as specified on the contract drawings or have screw-type terminals for use with locking fork lugs. Terminals shall be sized to accommodate the lugs and current involved and shall have a voltage rating suitable for the system.

Terminal blocks for thermocouple wiring (solid conductors) shall be equipped with pressure plates or wire clamps.

Short circuiting-type terminal blocks shall be provided for all terminations of current transformer wiring.

Other Hardware for Installation

Screws, nuts, bolts, flat washers, and lockwashers provided by contractor for electrical current-carrying connections or grounding connections shall be of a silicone-bronze alloy (or stainless steel) approved for electrical work. Hardware associated with an individual connection shall be either stainless steel or silicone bronze. Suitable flat washers and lockwashers shall be installed on all connections.

Screws, nuts, bolts, flat washers, and lockwashers furnished with manufacturer-furnished equipment (for example, switchgear, motor control centers, substation equipment and structures, or bus duct) for electrical current-carrying connections or grounding connections shall be installed as furnished, without substitution, regardless of the material supplied. Substitution of materials may result in performance issues or void manufacturer’s warranty.

Screws, nuts, bolts, flat washers, and lockwashers used for mounting electrical equipment shall be galvanized. Electroplated galvanizing is acceptable for bolt sizes 6 mm (1/4 in) in diameter and smaller. Suitable flat washers and lockwashers shall be installed on all connections.

Items such as anchor bolts, inserts, and support steel used for mounting electrical equipment on building steel, masonry, or concrete shall be provided by the contractor. The location of these items shall be verified by the contractor. All necessary items such as, brackets, rods, and hangers for supporting electrical equipment and conduit shall be furnished by the contractor. All support steel shall be hot-dipped galvanized or stainless steel. In cooling tower areas, water treatment buildings, and any other area subject to continuous moisture, all required conduit supports shall be aluminum or stainless steel.

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