Control of lighting should be flexible. Conveniently located, separate switches or dimmers should be installed for areas with different types of activities. It should be easy to extinguish lights for areas that are not occupied and to maintain minimal emergency lighting, for safety. Where feasible, daylighting should be used, supplemented, as needed, with artificial lighting. Light from windows can be reflected deeply into rooms, with venetian blinds, glass block, or other architectural elements. Glare and solar heat can be limited with blinds, shades, screens, or low-transmission glass. Provision should be made for decreasing or extinguishing supplementary artificial lighting when there is adequate daylight. Consideration should be given to use of photoelectric-cell sensors with dimmers for control of the artificial lighting. Maximum use of daylighting and other energy conservation measures are often essential, not only to meet the owners construction budget but also to satisfy the energy budget, or limitations on power consumption, set by building codes or state or federal agencies. Enhancing the functions performed by the power and lighting systems, the special systems in a building serve the life safety, communication, and security needs of a facility and its occupants. 15.19.1 Lightning Protection The design of lightning protection systems should conform with the standards of the American National Standards Institute, the National Fire Protection Association (Bulletin No. 780, Lightning Protection Code) and Underwriters Laboratories (Standard UL96A Master-Labeled Lightning Protection Systems). In deciding whether to provide a building lightning protection system, designers should first perform a risk assessment in accordance with NFPA 780, Lightning Protection Code. This evaluates such factors as building height, terrain, building construction, proximity to other buildings, type of occupancy, and isoceraunic level (frequency of thunderstorms). If the risk assessment warrants, a lightning protection system is designed. Protection for a building may be accomplished by several methods. An installation recognized by NFPA and UL consists of lightning rods or air terminals placed around the perimeter of the roof and on vertical projections, such as chimneys and the ridge of a peaked roof. These air terminals are bonded together and to a copper or aluminum conductor that extends down to a good electrical ground. There are also two less conventional types of installation that can be used. One involves the use of an air terminal containing a low-level radioactive source that produces a stream of ionized particles. This creates a low-resistance path that draws a lightning stroke to the air terminal, where it can be safely discharged to ground. The other type uses thousands of small air terminals spread along the high points of a structure to constantly dissipate any electrical charge in the air before it can build up high enough to induce a lightning stroke. The electrical wiring in a building is especially susceptible to the effects of a lightning stroke. To minimize these effects, a multilevel protective approach is used. Lightning arresters, which are connected from the phase wires to ground, are provided on the utility company lines and at the various voltage levels down to utilization voltage. Usually of the metallic oxide varistor (MOV) type, the arresters present a very high resistance to ground at normal system voltage, but quickly collapse to zero resistance during a lightning discharge, dissipating the discharge

Titanium dioxide and extended titanium pigments have high opacity and generally excellent properties. Various forms of the pigments have different properties. For example, anatase titanium dioxide promotes chalking, whereas rutile inhibits it. Colored pigments for building use are largely inorganic materials, especially for outdoor use, where the brilliant but fugitive organic pigments soon fade. The principal inorganic colored pigments are: Metallic. Aluminum flake or ground particle, copper bronze, gold leaf, zinc dust Black. Carbon black, lampblack, graphite, vegetable black, and animal blacks Earth colors. Yellow ocher, raw and burnt umber, raw and burnt sienna; reds and maroons Blue. Ultramarine, iron ferrocyanide (Prussian, Chinese, Milori) Brown. Mixed ferrous and ferric oxide Green. Chromium oxide, hydrated chromium oxide, chrome greens Orange. Molybdated chrome orange Red. Iron oxide, cadmium red, vermilion Yellow. Zinc chromate, cadmium yellows, hydrated iron oxide Extender pigments are added to extend the opaque pigments, increase durability, provide better spreading characteristics, and reduce cost. The principal extender pigments are silica, china clay, talc, mica, barium sulfate, calcium sulfate, calcium carbonate, and such materials as magnesium oxide, magnesium carbonate, barium carbonate, and others used for specific purposes. Natural and synthetic resins are used in a large variety of air-drying and baked finishes. The natural resins include both fossil resins, which are harder and usually superior in quality, and recent resins tapped from a variety of resin-exuding trees. The most important fossil resins are amber (semiprecious jewelry), Kauri, Congo, Boea Manila, and Pontianak. Recent resins include Damar, East India, Batu, Manila, and rosin. Shellac, the product of the lac insect, may be considered to be in this

Sid was good at explaining things and Josh felt he was making good progress in developing the skills he had learned at college. Sid kept emphasising the need to think carefully about each task and plan ahead. That way, you can help to avoid problems later on. The company had a contract to produce decorative brickwork in solid walling for a new retail park. The work required special bricks to be ordered. Josh was keen to try his hand at some of the fancy brickwork, but Sid said he should be patient and get the basics right first. When the special bricks for the job arrived on site, Sid was in the managers office. Josh decided to supervise the delivery and picked a good storage location, somewhere the bricks wouldnt be damaged. He told Sid that the delivery was sorted and gave the site manager the paperwork. After wet weather held the job up, the time came to start the feature work using the special bricks that Josh had previously taken delivery of. He arranged with the forklift driver to transport the first pack of bricks to the work area.