14-10 Section 1401
1401 -1 DESCRIPTION Design, furnish and install a high mount standard 60 feet or greater in height with a top- latched lowering device and port able drive unit including the drive, winch, wiring, cables, brackets, hardware, transformer, power cord, storage case and operating manuals. 1401 -2 MATERIALS
A.High Mount Standa rd Provide certified computations and fabrication drawings by a n engineer licensed by the State of North Carolina. Design the support including base plate and anchorage in conformance with the AASHTO Standard Specifications for Structural Supports for Hi ghway Signs, Luminaires and Traffic Signals , and the Interim Specifications as shown on the plans . Design and fabricate welds in accordance with Article 1072- 18. Design the support for the wind velocity shown in the plan s. Have the drawings show all deta ils relating to pole, access hole, base, anchorage and lowering device. Show references to ASTM specifications or to other material specifications for each type of material used on the drawings. Note the total weight in pounds on the drawings for each com ponent and the total assembly. Make sure that all drawings are clearly identified with a drawing number and signed and dated by the manufacturer's authorized representative. Clearly identify all welds on the working drawings utilizing welding symbols and provide all information regarding location, type, size and extent of all welds. For groove welds, indicate complete joint penetration (CJP) or partial joint penetration (PJP) groove weld requirements . Prequalified joint designations shall be in accordance with the AWS D1.1 Structural Welding Code - Steel, for the welding process to be employed during production. Submit welding procedures and procedure qualification records to the Engineer for approval before fabrication. The standard may be e ither a multisided or round tubular member. The criteria listed below shall apply to 60 feet, 80 feet, 100 feet an d 120 feet high mount light poles:
1.Provide eight or more anchor rods for each pole.
2.Provide base plate thickness of at least 2.5 inches .
3.Provide welded wire reinforcement for base protection that meets Subarticle 1400- 4(I). Electronically submit complete working drawings and complete design computations for each height of standard for approval by the Engineer before fabrication. Fabricate t he support in accordance with the details shown on the approved shop drawings and the s pecifications . Test all base plate to upright welds using magnetic particle testing (MPT) before galvanizing. All base plates must be tested at 100%. Radiographically test the longitudinal seam welds within 6 inches of the base plate and within 6 inches of the larger end of the outer tube of the slip fit joint area. Hot dip galvanize metalwork after fabrication has been completed. Ensure the galvanization conforms to A STM A153 for fasteners and ASTM A123 for other
14-11 structural steel. All welds shall be abrasive blasted to an SSPC SP6 condition before
galvanizing. Partial penetration longitudinal groove welds on shaft sections, having a minimum throat of 60% of the thickness of material being joined, will be acceptable provided the qualification requirements of the Structural Welding Code - Steel, AWS D1.1 are met. However, full penetration will be required on longitudinal groove welds within 6 inches of circumferential w elds and in areas where a shaft section telescopes over another shaft section. No field welding of any part of the assembly will be permitted. Allow easy access to all components in the base of the standard with a hand hole with a hinged and lockable door . Allow for opening of the door without the use of special tools or wrenches. Make the hand hole large enough for removal of the circuit breaker and the hoist gearbox and winch assembly (at least 9 inches x 18 inches .) Make the door hinge and lock mecha nism sturdy enough to prevent vandalism and to prevent freeze -up or binding due to corrosion or too tight fit. Provide locks and keys in accordance with
Article 1400 — 8. Built- in locks or latching mechanism for the door will not be acceptable.
B.Lowering De vice Electronically submit complete detailed drawings of the lowering device with manuals describing the assembly, erecting and operating procedures. Include precise instructions on stringing the cables and leveling the carrier ring. Each high mount light standard shall have a device to lower the luminaires from the operating position at the top of the standard to a service position approximately 3 f eet above the base of the standard. Include on the device a head- frame, top latching carrier ring and winch assembly. Design the lowering device for the number of luminaires as shown in the plan s. Maximum high mast luminaire weight and effective projected area are shown in the specifications . Mount the head frame on the standard with a slipfitter and set scre ws, and have sheaves or rollers for the lifting and power cables. Ensure sockets automatically secure the carrier ring at the top in the raised position and provide a hood on the entire assembly for protection from the weather. Attain latching and unlatc hing by alternately raising and lowering the carrier ring. Use sheaves that are non -corrosive materials with bronze bushings and stainless steel shafts. Provide suitable retainers to assure that the cables stay in correct position. Have slipfitter tenons equally spaced for mounting the luminaires on the carrier ring. The tenons shall be a suitable length to allow the installation of the LED luminaires. Have the carrier ring automatically latched to the head frame when raised into position by suitable pins and sockets which will prevent the luminaires from swaying, turning, vibrating, or otherwise moving out of proper position. Include on the carrier ring spring loaded roller arms to guide the ring during raising and lowering operations. Use springs made of stainless steel and rollers made of nylon. Mount a metal NEMA 3R weatherproof junction box on the ring for connection of individual luminaire circuits to the electrical power supply cable. Include in the junction box a flanged inlet for connection of the power supply cable. Use an inlet and cable connector which are of the locking type and weatherproof. Use a winch assembly that is a self -locking worm gear type designed for operation with a portable power unit. Have the winch drum automatically reve rse the lay of the hoist cable and prevent uneven build- up or tangling. Provide a terminator for joining the hoist cable and three suspension or lifting cables. Provide the means to compensate for variations in the lengths of the 3 lifting cables. Use hoist and lifting cables made of stranded high strength stainless steel extra flexible aircraft type. Use hoist and lifting cables that meet structural requirements of Military
14-12 Specification MIL -DTL -83420 and have the center strand not protruding more than 0.06
inch after the cable is cut. Use a power supply cable that is rated for suspension and has approved strain relief fittings at each end. At the base of the standard, provide a locking type plug with waterproof cover to connect to a short power supply cable stubbed from the circuit breaker panel.
C.Portable Drive Supply a portable drive unit with a heavy duty reversible electric motor with torque limiter type drive of adequate capacity, complete with a grounding type cord, suitable couplings for at taching the unit to the winch assembly, and a sturdy storage container for the unit and accessories involved. Provide one portable drive unit for the completed project. Provide a drive unit with a lever switch controller with clearly marked up and down positions. Connect the controller to the drive unit with a cord of sufficient length to let the operator stand a minimum of 15 f eet from the base of the high mount during lowering or raising operations. Shop assemble the portable drive unit and remove all rough edges. Use mounting or adjustment bolts which allow hand tightening. Provide a complete unit that includes a durable metal storage case with all equipment and instructions for operation. Use a case which is the approximate size as shown in the plans, has a continuous hinge on the lid, and has sturdy carrying handles on each end. Furnish a hasp with padlock as shown in the plan s. Construct the case with 16 gauge formed and welded steel with bracing to prevent warping. Paint the inside and outside with a durable quality paint. Provide an identification label as noted in the plans on the storage case.
D.Circuitry Install an enclosed circuit breaker in the base of the high mount standard. Use a breaker which is rated 480 VAC, 2 pole, 30 A, and a minimum interrupting capacity of 14,000 A unless noted otherwise in the plan s. Provide a supply cord originating from the circuit breaker with a female twist lock connector for testing the luminaires at ground level, during lowering operation using the portable drive unit and when in the raised position during normal night operation. Provide a metal NEMA 3R weatherproof junc tion box mounted on the lowering ring with a flanged inlet to accept the female twist lock connector from the supply cord. Use plugs, flanged inlets and connectors for the supply cable and drive unit which allow grounding and are weatherproof. Install the wiring for each high mount luminaire separately from the luminaire to the junction box. Series or loop circuitry is not allowed. Provide a transformer, branch circuit breaker or minimum 5A fuse and GFCI receptacle as a power source for the portable drive . Provide an equipment grounding conductor in the supply cable. Include an equipment grounding conductor in the wiring for each luminaire. Provide a High Mount Junction Box sized as shown in the plans and meeting the requirements of Section 1411. Provide a ground rod in accordance with Subarticle 1400 -2(D).
E.Operation Demonstrate the operation of the lowering device by raising and lowering the carrier ring with luminaires a minimum of five times for each high mast. Include in this
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 710–712 of 857.