Main keywords for this article are Electrical Lighting System Design Notes, Lighting Panel boards, Electrical Branch Circuits, Flood Lighting, lighting and receptacle circuit wiring.
Electrical Lighting System Design Notes in Plants Buildings
- Equipment related to lighting systems, transformers, panel boards and fixtures shall be installed to not interfere with the normal clearances allotted for personnel and equipment.
- Where possible, lighting circuits shall be arranged with the lighting distributed in a way that allows minimum evenly distributed lighting upon circuit deenergization and for energy saving when higher levels of illumination are not required.
- Lighting fixtures shall be listed and labeled by Underwriters Laboratories or equivalent labeling.
Lighting Levels
- Lighting levels shall be in accordance with Lighting Design Requirements in Process Industry Table I.
- These are in-service values, after a maintenance factor of 0.65 has been applied, or a factor of up to 0.85 may be used indoors in air conditioned or pressurized areas. The Lux illumination levels are average vertical component values for the locations described at a horizontal plane 76 cm above the floor, ground or platform.
Lighting Transformers
- Lighting transformers shall be in accordance with Lighting and Receptacle Circuit Wiring Requirements and approved for the area classification they are to be installed in. The utilization voltage shall be selected from section below. Alternatively the primary voltage can be Medium Voltage if there is no 480V available.
- The transformers shall be provided with four 2.5 percent full capacity taps, two above and two below the rated primary voltage.
- Transformer sizes shall be standardized at 15, 30, 45 and 75 kVA depending upon load requirements.
- A lighting transformer shall be provided for every lighting panel board. The initial panel board load shall not exceed 70 percent of the transformer capacity.
Lighting Panel boards
- Lighting panel boards shall be in accordance with Lighting and Receptacle Circuit Wiring Requirements.
- The 400Y-230 V branch circuits shall be protected by 20 A air circuit breakers housed in lighting panel boards.
- Panel boards shall be equipped with a main breaker.
- Panel boards shall be; approved for the area classification; suitable for the corrosive atmosphere in which they may be installed; and located as close as practical to the load to be served.
- Panel boards installed indoors or outdoors in hazardous areas shall be explosion proof NEMA 7.
- Panel boards installed indoors in non-hazardous areas shall be NEMA 4.
- Panel boards installed in corrosive atmospheres shall be NEMA 4X fiberglass reinforced polyester or equal.
- Separate panel boards shall be provided for non-lighting load, for example single phase motors, receptacles, and instrument power circuits.
- Panel boards installed outdoors shall be provided with breathers and drains.
- Panel board load distribution shall be based on balanced loading of its transformer.
Electrical Branch Circuits
- Branch circuit breakers for lighting, receptacles and single phase motors shall be single pole, rated at 20 A.
- Single or two pole breakers with ratings higher than 20 A may be required for special load requirements.
- Initial loading on branch circuits shall not exceed 70 percent.
Lighting Fixtures
- General lighting where an outdoor industrial process or procedure takes place shall be provided by high pressure sodium or HID fixtures with high power factor ballasts. These fixtures shall be provided complete with globe, guard and reflectors.
- The use of flood lighting shall be maximized, with supplemental local fixtures added as required. Flood lights and local fixtures shall have integral ballasts.
- Offices, control rooms and similar indoor areas shall be illuminated with commercial and industrial type fluorescent fixtures provided with thermally protected
rapid start ballasts.
Flood Lighting
- Floodlighting fixtures shall be 230 V, single phase, high pressure sodium or mercury type. Power supply to flood lighting systems shall be fed from 3 phase 4 wire feeders. Adjacent flood lights shall be fed from alternate phases.
- Three pole circuit breakers and contactors shall be provided for floodlighting circuits.
- Floodlighting shall be photocell controlled with manual override.
- Floodlights may be mounted on platforms, structures or poles. Poles shall be spun aluminum. Aluminum poles installed in corrosive areas shall be painted or coated with an anticorrosive.
Street Lighting
Plant street and roadway lighting shall be mounted on 10 m high light poles. Lighting shall be provided at street intersections.
Pipeway Lighting
Pipeway lighting shall be lighted to a minimum level, but shall still provide for safety. An intensity of 20 lux shall be considered a reasonable minimum level.
Control Room and Indoor Lighting
- Fluorescent lighting fixtures provided with rapid start ballasts and RFI filters shall be used for indoor lighting.
- Manual switches located at the entrance of each office or equipment room shall control the lighting for that room.
- The control room lighting shall be coordinated with the instrumentation equipment locations to minimize glare and reflection on panel mounted instruments and meters, CRT displays and annunciators.
- Control room lighting shall incorporate multilevel switched fixtures or dimmers and special louvers over the fixtures to distribute light to reduce glare and reflection on CRT displays.
Local Instrument Lighting
- Where required by the process, through vision gage glasses shall be provided with special lighting fixtures designed for the purpose. Lamps for these fixtures shall be the long life type. Gage glass lights shall have a local control switch mounted adjacent to the unit for individual control.
- Special lighting for individual field mounted instruments shall not be provided. Lighting fixtures for general illumination shall be mounted as close as possible to instruments to provide lighting.
- The interior of walk in instrument shelters and under the weatherprotective hoods in front of local control panels shall be provided with lighting to permit the reading or maintenance of instruments at these locations.
Emergency Lighting
- Emergency lighting shall be concentrated in areas critical to orderly plant shutdown and emergency services. Typically these locations are:
a. control rooms, switchgear rooms and emergency generator locations.
b. local control and instrument panels.
c. essential process equipment and process control stations.
d. safety showers and eye wash stations.
e. fire control panels and areas around fire pumps. - Minimum of 20 percent lighting for outdoor process areas and buildings shall be on emergency power.
- Self contained, rechargeable, nickel cadmium battery powered lighting units that can be switched on automatically in the event of loss of normal power are suitable for egress lighting.
- Illuminated exit signs shall be on emergency power.
- Light fixtures fed from emergency power shall be provided with instant or rapid restart ballasts.
- Emergency lighting at plant buildings shall comply with requirements of SAF-03.
Lighting Control
- The normal switching of outdoor lighting shall be by photocell control of an airbrake magnetic contactor. A manual override of the photo cell shall be provided. The photo cell, manual override switch and contactor shall be located adjacent to the lighting panelboard, in an enclosure suitable for the environment and approved for the area classification.
- Rooms, for example individual offices, equipment rooms, washrooms, and instrument shelters shall be provided with local switches in enclosures suitable for the environment and approved for the area classification.
- In industrial or process facilities where, for example, structures, columns, and towers have lighting on platforms above the grade level, a local switch shall be located at grade, at the base of the ladder or stairs leading up. This will permit turning off the lights on the upper elevation platforming when no longer required.
Convenience Receptacles
- Convenience receptacles for 230 V, single phase non-process area shall be provided with 30 m extension cord to furnish a source of power for portable power tools and extension lighting, for maintenance and repairs. Maximum four receptacles shall be connected to a 20 ampere branch circuit.
- The receptacles in the process area shall be positioned in a way that locations where portable power is required shall be within reach of a 15 m extension cord. Maximum four single receptacles shall be connected to a 20 ampere branch circuit.
- In process areas with vertical columns and towers, a receptacle shall be located at the base and on every platform providing access to a manway.
- Receptacles shall be installed not more than 20 m apart, on all working platforms and tall structures so any location where portable power is expected shall be within reach of a 30 m extension cord.
- Receptacles shall be suitable for the atmosphere and approved for the area classification they are installed in.
- Receptacles shall have only bottom cable entries.
- Receptacles shall be grounded through the ground core of the cable in addition to the requirements of NEC Article 250.130(A).
Welding Receptacles
- A number of 480 V, three phase, 60 Hz, 60 ampere circuits shall be provided for supplying power to, for example, portable pumps and welding machines.
- Welding receptacles shall be located so that 40 m ac power cords can cover all areas of the plot.
- Plugs shall be provided with the welding receptacles, with one plug for every ten receptacles installed.
- Branch circuit protection for the welding feeders shall be provided by remotely located thermal magnetic circuit breakers.
- Overcurrent protection and a disconnecting means shall be provided as an integral part of the welding machine in accordance with NFPA 70 (NEC).
- Welding receptacles shall be connected for a common phase rotation to match the existing rotation, when installed in existing facilities.
Lighting and receptacle circuit wiring
- Lighting circuits wiring shall be color coded, single conductor 90ºC, cross linked polyethylene (XLP), UL type XHHW or equal, in rigid conduit or metal clad (MC) 90ºC, XLPE, multi-conductor cable with overall PVC jacket, suitable for cable tray installation.
- In buildings with finished walls, for example control centers or offices, wiring for lighting, receptacle power and other systems may be installed in Electrical Metallic Tubing (EMT). In addition to the single conductor branch circuit wiring a ground wire shall be included in the EMT.