For 40 years CU have been engaged in a continuous process of research and development of High Masts. Over those years CU have built up a wealth of experience unique throughout the world in the structural, mechanical and electrical aspects of high mast design, production and maintenance. The basis of this experience forms the specification on which our masts are manufactured. We have outlined the specification in blue italics followed by supplementary information. CU are able to supply masts for use in Zone 2 Hazardous areas with special power cables, plugs and sockets, junction boxes, cable glands, contactors and power tool. A separate specification is available for this type of mast.
The Masts shall be continuously tapered of polygonal cross section, presenting good visual appearance. CU masts are duo-decagonal (20 sided). Masts are often made to suit clients' particular requirements.
The masts shall be designed to I.L.E. Technical Report 7 on the maximum wind speed (3 second gust) likely to be exceeded only once in 50 years, measured at a height of 10 metres above level ground. Wind excited oscillation shall be damped by the method of construction and adequate allowance made for the related stress. Full design calculations for the mast will be provided by the manufacturer.
CU masts have been subject to full scale destructive testing by the CEGB at the structural test centre at Cheddar. The test proved our design calculations and exceeded the predicted failure load, and final test to destruction confirmed the manner and location of failure expected by our engineers. CU masts have also been wind tunnel tested at the De Havilland wind tunnel to derive the correct shape coefficient for use in our calculations. CU’s design department is certified to BS EN ISO 9001 for the design of high masts and other lighting columns.
All steel used in the construction of the masts shall comply with BS EN 10 025 of appropriate grade. Welding shall be in accordance with BS EN ISO 1011.
The masts shall be constructed from mild steel plates cut and folded to form a polygonal section, telescopic jointed and fillet welded, with the exception of site joints.
Each mast section delivered over 6m in length shall include a telescopic and welded joint to provide diaphragm stiffness and to maintain the structural section during delivery.
A door shall be provided in the base of the mast to permit clear access to equipment. The door shall be weather and vandal resistant with a heavy duty lock. The base flange welded connection to the mast shall fully develop the strength of the section. In addition, supplementary gussets shall be provided between bolt holes. The mast shall be delivered to site in sections and joined with stressing equipment, thus forming a sleeve joint - no site welding or bolted joints will be permitted.
CU's weld geometry and procedures have been developed in conjunction with an internationally established welding consultant.
The entire mast shall be hot dip galvanised after fabrication, internally and externally, in accordance with BS EN ISO 1461.
Mast can be 'T' washed, etch primed at the factory for painting on site.
For installation and maintenance purposes it shall be possible to raise or lower the lantern carriage using a winch in the base of the mast. The steel wire rope supporting the lantern carriage shall be in tension at all times to prolong rope life and will not depend on latches for security.
Stadium masts have a fixed head with lift system or ladders. Through many years of experience of many thousands of masts CU's policy is the pursuit of simplicity. The minimum number of moving parts and absence of complication ensure the longest possible trouble free life. However if the client insists on latching devices, CU are able to supply such a system.
The pulleys shall be of large diameter, appropriate to the multicore flexible cable being used. They shall be of non-corrodible material and run on self-lubricating bearings with stainless steel spindles. Arrangements shall be provided to ensure that the electric cables and steel wire ropes are separated before passing over their respective pulleys to prevent ropes and cables leaving the pulleys’ grooves.
The pulleys shall be housed in a chassis integral with a sleeve which slips over the top of the mast and is secured axially and in azimuth. Guides and stops shall be provided for docking the lantern carriage. The complete chassis assembly shall be hot dip galvanised after fabrication.
The pulley assembly shall be protected by a weatherproof cover.
Assemblies with more than the standard four pulleys can be supplied if necessary. Three point suspension is also an alternative design offered by CU.
The lantern carriage shall be of durable steel tube designed to act as electric conduit, with cable holes fully protected by grommets. It shall be fitted with junction box mounting plate(s) and be in two halves joined by bolted flanges to permit removal from the erected mast.
Lantern fixing arms and plates shall be welded to the carriage. The carriage shall incorporate buffer arrangements to prevent damage to the mast finish and luminaires and not require rollers or other moving parts.
If required, lantern carriages can be fitted with screens or canopies.
Winches shall be completely self-sustaining without the need for brakes, springs or clutches which require adjustment, or which can be affected by moisture or lubricant. The gear ratio shall be 53:1. The winches shall be self-lubricating by means of an oil bath, and lubricant recommended by the supplier shall be used.
Termination of the winch ropes shall not involve distortion or twisting of the rope structure. At least four turns of rope shall remain on the drum when the lantern carriage is fully lowered. In the case of multi-drum winches each rope shall be direct from lantern carriage to winch and not include any intermediate connection. The winch shall be designed to be installed or removed through the door opening. Winch drums shall be grooved to ensure a tidy rope lay and be fitted with a device to ensure smooth return of the rope for each layer. A test certificate shall be supplied with each winch. The capacity, operating speed and recommended lubricant shall be clearly marked on each winch with an indelible label. The winch shall be capable of operation by hand or by means of a power tool. The driving spindle shall be positively locked when not in use by automatic means. Each winch shall be supplied with a fitted
waterproof cover.
The patented CU double drum winch is to be preferred where price is not the only consideration. The twin independent drums are both capable of lowering the luminaires alone. The drums are attached directly to the lantern carriage without any intermediate connectors. The drums can each be adjusted individually so any difference in the elasticity of the ropes does not affect the lantern carriage.
The power tool shall be a multi-speed reversible tool incorporating a torque limiting device which can be readily adjusted and locked. A remote control switch shall be incorporated to allow the equipment to be operated from a distance of 5 metres. Arrangements shall be provided to support the power tool accurately and securely during operation.
Handles shall be provided for manual operation of the winches and they will also incorporate a torque limiting device which can be adjusted and locked.
Steel wire ropes shall be flexible 'marine grade' stainless steel of 7/19 construction. Thimbles and terminals shall be of compatible material. Steel wire ropes shall be factory cut terminated and pre-rigged for ease of installation. Ropes with hemp or nylon cores shall be not used.
Multi core flexible round sheath power cables shall be provided, terminating in the base compartment of the mast, fitted with plugs and sockets and a guard ring. At the mast head, cables shall be connected to a weatherproof junction box on the lantern ring equipped with suitable nylon glands. The equipment shall be suitably rated for the required duty. Power cables shall be factory cut and pre-rigged for ease of installation.
CU's standard equipment uses single or twin 7 core cable or alternative core can be supplied up to a maximum of 6 cables per mast.
Guaranteed performance, medium tensile, high yield, galvanised holding down bolts shall be supplied, complete with anchor plate for casting into the foundation. A precision made steel template with tubed holes, to ensure correct vertical and horizontal bolt alignment, shall also be provided.
A 12mm diameter stainless steel bolt shall be attached to the mast structure at a convenient point within the base compartment to provide a lightning and cable earthing point.
An extension lead or leads of multicore cable, equal to that within the mast and fitted with a plug and socket, shall be provided to enable the lanterns and permanent supply cable to be tested when in the lowered position, using the base compartment socket supply.
