HAZARDOUS LIGHTING FROM SAFETY TO SAVINGS. IGHTING IN HAZARDOUS (CLASSIfied) locations poses application challenges in

Transcription

1 HAZARDOUS LIGHTING FROM SAFETY TO SAVINGS BY ROBERT C. POTTER JR. & DONNA LEE HODGSON IGHTING IN HAZARDOUS (CLASSIfied) locations poses application challenges in L Class I, Division 2 areas that require improved temperature classes (T-ratings or T- codes). For instance, oil refineries classify numerous areas with a T3 temperature class rating. A 70-W high-pressure sodium (HPS) light source achieves this rating. The often-preferred level of 100 or 150 W typically obtains a T2A or T2B rating. This article explores the use of restricted breathing to achieve a T3 rating. This maintains the proper approvals for safety, while producing cost savings associated with reduction of material and, subsequently, installation costs. The authors will review, through a case study and project cost estimates, the savings and benefits achieved for a 175,000-barrel/day refinery on the East Coast of the United States. The latter sections of this article examine a lighting upgrade enlisting the newly available restricted breathing technology. The savings of 48% for reproducing the same illuminance or 24% for producing even and adequate lighting will be illustrated by comparing the cost of this upgrade to estimates of upgrades that do not use restricted breathing. An estimate of a new installation saving 51% using restricted breathing will be compared to one that does not. The article with describe in detail how these estimates and savings were determined. Backgound Restricted breathing developed as a method of protection under the Ex techniques. The Ex technique refers to the International Electrotechnical EYEWIRE Commission (IEC) standard of explosion protection in classified areas. The IEC symbol nr represents restricted breathing. It is categorized under the electrical apparatus type n protection which under normal operation, is not capable of igniting a surrounding explosive gas atmosphere and a fault capable of causing ignition is not likely to occur [1]. Completely comprehending the restricted breathing technology first requires an understanding of how temperature classes (T-ratings) are developed. Substances have /07/$ IEEE

2 32 a minimum ignition temperature required to initiate or cause self-sustained combustion. A temperature class indicates the maximum heat that a piece of equipment will produce. This allows engineers to choose products that will not ignite surrounding substances. For example, Heptane has an autoignition temperature of 204 C. Therefore, a luminaire would require a T3 rating (200 C maximum temperature), as a T2D (215 C maximum temperature) would operate in excess of the ignition temperature. (a) Developing temperature class (T-ratings). TABLE 1. T-RATING COMPARISON (AMBIENT TEMPERATURE OF 40 ºC). Class I Division 2 (Zone 2) Nonrestricted Restricted Lamp Watts Breathing Breathing HPS 50 T3A T5 70 T3 T4 100 T2C T4 150 T2A T3 Metal Halide 70 T3A T5 100 T2D T4 150 T2A T3 175 T2A T3 Mercury Vapor 100 T2B T4 175 T2 T3 Induction 50 T2B T6 85 T2B T6 (b) Prior to 1971, temperature ratings were part of the group classification process. Equipment intended for Group A, B, and D locations were limited to a maximum surface temperature of 280 C. Equipment for use in Group C was limited to an external surface temperature of 180 C. In the 1971 edition of the NEC, a system of marking equipment with temperature ratings to identify the external surface temperature was put into place. A requirement was established that equipment could not be used in areas where the ignition temperature of the flammable material was less than the temperature rating marked on that equipment [2]. As illustrated in Figure 1, temperature probes are secured to measure the heat produced. Figure 1(a) demonstrates the technique used to measure the temperature class on a Class I, Division 1 luminaire by connecting temperature probes and sensing the hottest point on the surface (typically the globe). Since the unit is explosion proof, the warmer internal components are not of concern, as any explosion will be contained within the fixture. Figure 1(b) demonstrates the testing procedure for a Class I, Division 2 luminaire by testing the hottest points internally (typically, 1 the lamp). The Division 2 fixture is designed to contain hot sparks or metal and operate at designated temperatures, but is not engineered to contain an explosion as with the Division 1 unit. This internal reading is required so that during a fault condition, if the flammable gas or vapor enters the luminaire, the interior temperatures are not capable of igniting the mixture. The Theory Restricted breathing, as a method of protection, should not be confused with IEC versus NEC or zones versus divisions. The 1999 edition of the National Electrical Code (NEC) (NFPA 70) under Article began permitting material listed for Zone 0, 1, or 2 to be a recognized method of protection in Class I, Division 2 locations, provided that the product operates at a suitable temperature class. The 2005 edition of the NEC under Article states, Equipment listed and marked in accordance with 505.9(C)(2) for use in Class I, Zone 0, 1, or 2 locations shall be permitted in Class I, Division 2 locations for the same gas and with a suitable temperature class. Luminaire housings for restricted breathing are tested to eliminate or sufficiently limit flammable gases or vapors from entering the fixture. Incoming conduit is sealed to prevent the gases from entering the luminaire. These seals are not required to be traditional explosion-proof fittings. Electrical putties are an adequate means of sealing the conduit. Finally, the proper nameplate is affixed to the fixture, displaying the restricted breathing method of protection for Class I, Division 2 and the associated temperature class (T-ratings).

3 By preventing flammable gases and vapors from entering the luminaire, the temperature class is no longer determined by the hottest point internally. Now, the classification may be achieved using the hottest point externally, as done with the Class I, Division 1 unit. The temperature difference between the inner portion of the luminaire and the surface averages 80 C (depending on light source and fixture style) but may be up to 175 C. Benefits A benefit of restricted breathing is that it allows industry to specify higher wattage luminaires. This reduces the number of units required, while maintaining the necessary temperature class. In the past, applications for Class I, Division 2 luminaires, with the presence of a substance having a low auto-ignition temperature, may have facilitated the use of Class I, Division 1 luminaires to maintain an acceptable temperature rating. Restricted breathing technology may allow for the usage of a less expensive Class I, Division 2/Class I, Zone 2 style of fixture while achieving the required temperature class of a particular gas. Table 1 compares the temperature class differences of the traditional Class I, Division 2 luminaire and that of the same unit adopting the restricted breathing technology [3]. The temperature classification chart shown in Table 2 lists the maximum surface temperature for the 14 NEC and six IEC T-codes. The Next Generation Nonsparking Apparatus New enhancements continue for the restricted breathing technology. An additional method of protection listed under the type n technique is known as nonsparking apparatus or nonsparking equipment represented by the symbol na. When combining the nonsparking method of protection with restricted breathing, the result is a restricted breathing luminaire that does not require sealed conduit entries. Nonsparking protected luminaires seal the globe chamber at the lamp socket. Since this design assumes the gas or vapor may enter the ballast housing but not the globe chamber portion of the unit, the temperature class reading is now taken on the surface of the globe chamber as well as internally on the ballast. The higher of the two readings establishes the T-code. This technique also provides improved temperature class ratings over the traditional Class I, Division 2 luminaire. Induction Lamp System Induction lamp luminaires are now becoming available with the restricted breathing option. When combining the induction luminaire with restricted breathing technology, temperature class ratings improve from a T2D/ T2B to a T6 (T2D and T2B are approximations, since RESTRICTED BREATHING DEVELOPED AS A METHOD OF PROTECTION UNDER THE EX TECHNIQUES. wattage, housing, and refractor configurations may adjust the actual temperature performance). The induction lamp, shown in Figure 2, is an electrodeless hybrid fluorescent lamp providing for 100,000-h lamp life, extending relamping for years. Cold weather becomes less of an issue for the instant-on induction lamp, because the minimum operating temperature of this lamp is 40 C. High-frequency currents are produced by a generator and sent to the induction coil in the power coupler in the lamp, creating a magnetic field. This magnetic field induces a current, which excites the mercury ions in the lamp, emitting ultraviolet (UV) radiation. Fluorescent phosphors coating the inside of the lamp TABLE 2. TEMPERATURE CLASSIFICATIONS. IEC79-8/ Max. Surface NEC EN Temp (C) Table 500.8(B) T Class 450 C T1 T1 300 C T2 T2 280 C T2A 260 C T2B 230 C T2C 215 C T2D 200 C T3 T3 180 C T3A 165 C T3B 160 C T3C 135 C T4 T4 120 C T4A 100 C T5 T5 85 C T6 T6 Induction lamp. HF Generator Bulb Power Coupler 2 33

4 34 emit light when struck by the UV radiation [4]. Induction lighting as an instrument for lighting in hazardous (classified) areas was first introduced to the 2002 Petroleum and Chemical Industry Conference (PCIC) in a paper titled Lighting and Control Advancements for Hazardous areas in Industrial Facilities [5]. Project: Lighting Upgrade Three Approaches In the next two sections, the following versions of a lighting upgrade project will be examined: 1) a detailed estimate of the upgrade not using restricted breathing luminaries; this design is intended to produce a level of illumination that the project managers desire, which is comparable to what is achieved in the case study mentioned later 2) a detailed estimate of the upgrade not using restricted breathing luminaries; this design will produce adequate lighting, meeting the minimum standard of the API 540 3) a case study using restricted breathing fixtures. We will compare the estimated cost of a new installation design using restricted breathing versus one that does not. Finally, other cost-saving intangibles will be discussed. Background The crude unit in this refinery was recently reclassified. Approximately 30% of the unit went from a T2A rating to a T3 rating. The rest of the unit remained rated T2A. This reclassification forced a reexamination of electrical equipment in the area, in particular, the existing incandescent lights and some recently installed HPS lights. The incandescent lights were installed before the practice of giving temperature ratings to classified areas was adopted. These 150-W incandescent lights were determined to operate at a temperature comparable to a T2C rating or higher. The 150-W HPS fixtures were rated T2A. Neither fixture was properly rated for the electrical area classification. Equipment rated T2C and T2A has surface temperatures up to 230 C and 280 C, respectively. Areas with a classification of T3 will safely tolerate temperatures up to 200 C. The decision to upgrade the lighting was made. Since the operators were used to the existing 150-W HPS fixtures, project managers elected to design the installation to maximize lumen output. A BENEFIT OF RESTRICTED BREATHING IS THAT IT ALLOWS THE INDUSTRY TO SPECIFY HIGHER- WATTAGE LUMINAIRES. TABLE 3. ESTIMATE 1: 122 ADDITIONAL FIXTURES. Description Material Cost Labor Cost Total Cost Estimate 1 US$85, US$152, US$238, The scope of this project is the replacement of W incandescent fixtures and W HPS fixtures with new 100-W HPS restricted breathing fixtures for a total of 193 replacements. The lighting was not replaced in the area classified as T2A, since the existing lighting was adequately rated. Standards The project was evaluated and estimated based on the following specifications: 1) All branch circuit conductors will be 600 V, type THWN, stranded, single copper conductors of size AWG 12. 2) Conduits are rigid steel hot dip galvanized no smaller than 3/4 in. 3) The illumination levels meet or exceed the minimum standard of the API RP 540, which recommends at least 5 foot-candles (fc.) at ground level in general process units [6]. 4) The installations will meet all requirements outlined in the most recent edition of the NEC. 5) The design will be practical, taking efficiency and maintenance into consideration. The (estimated) versions of the project that do not use restricted breathing fixtures will be designed with the materials that were available at the time. Prices from 2002 will be used in the estimate. When 2002 prices are not available, an inflation factor (3% per year) will be used to estimate the material cost. All costs associated with the project will be included, and the designs will utilize the most economical and/or reliable materials available at the time. Detailed Estimate: Upgrades Without Restricted Breathing Scope Development The permissible temperature of the part of a luminaire that comes in contact with surrounding gases restricts its power rating. To mitigate the surface temperature of a luminaire, the wattage must be limited. In this case, reduced power equates to reduced lumen output. Recalling from Table 1, up to 70-W HPS fixtures (of the nonrestricted breathing type) may be installed in an area classified as T3. The following two designs will replace 193 fixtures with 70-W HPS fixtures. In each design, new fixtures will need to be added. In the case study, described in the following section, the new fixtures were replaced with 100-W HPS restricted breathing fixtures. The first of the two estimates will determine what would be the cost to bring the illuminance of the project (not using restricted breathing) to the same level of illuminance achieved with restricted breathing. This will be accomplished by adding

5 new fixtures in a manner that produces an equivalent amount of luminance to what the project managers desired (and achieved in the case study). The second estimate will be more practical. An engineer may be less concerned with lumens per square foot than providing even and appropriate lighting while meeting the minimum standards. This second estimate will encompass the replacement of 193 fixtures with 70-W HPS nonrestricted breathing fixtures. Additional 70-W HPS fixtures will be added to produce even and adequate lighting. The original power system was designed for 150-W incandescent fixtures and 70-W HPS fixtures, with a total load of 91 W, and will decrease the load on each circuit. This makes it easier to splice into existing wiring and add new fixtures. Except where noted, the following estimates were compiled using the following assumptions: 1) Each additional fixture requires an average of 60 ft of 12 American wire gauge (AWG), 600-V, type thermoplastic, insulated, heat and moisture resistant, nylon-jacketed cable 75 C, dry and wet location (THWN), stranded conductors, a Grouse-Hinds model number (GUAT) conductor box, three unions, and an average of 20 ft of conduit. 2) 25% of this new conduit will be 1 in; the remaining will be 3 4 in. 3) Wires will need to be pulled on 10% of the installations; the remaining new additions will be spliced. Estimate 1: Achieving Equal Lumen Output The power distribution system is already in place. The challenge will be to design the addition of enough 70-W HPS fixtures so that the lumen output is equal to it being lit by 100-W HPS fixtures. The total lumens produced by replacing the 193 existing fixtures with 100-W HPS fixtures was calculated by multiplying the total lumen output per luminaire by the total number of fixtures. The total lumen output used in the calculation is the nominal lumen output, obtained from the manufacturer s photometric data reports (9,500 lumens) (193) = 1,833,500 lumens. The number of 70-W HPS fixtures needed to produce this amount of light output is APPENDIX A TABLE A-1. DETAILED ESTIMATE OF LIGHTING UPGRADE WITH 70-W NONRESTRICTED BREATHING FIXTURES TO PROVIDE EQUAL LUMINANCE. US$ per Total Material MHU b Total US$ per Total Labor Total Cost, Description Units Qty. each Cost, US$ per unit MHU MHU Cost, US$ US$ 70-W HPS EA a 315 $ $63, $82.00 $77, $141, Fixture 70-W Lamp EA 315 $7.50 $2, $82.00 $6, $8, in Conduit 100 ft 18.3 $ $2, $82.00 $24, $26, in Conduit 100 ft 6.1 $ $1, $82.00 $8, $9, AWG 1/C 1,000 ft 7.4 $ $1, $82.00 $6, $7, V Termination EA 244 $1.00 $ $82.00 $3, $3, AWG 12 Wire Pull 100 ft $82.00 $11, $11, Unions EA 126 $8.00 $1, $82.00 $1, $2, Conduit Boxes EA 42 $29.50 $1, $82.00 $1, $2, (GUAT) Epoxy EA 42 $5.00 $ $82.00 $ $ Compound Engineering EA $ $12, $12, Overhead EA 1 $11, $11, and Profit Total $238, a EA each b MHU Man-hour units 35

6 1,833,500 lumens = 315 lamps. (5,800 lumens/lamp) These initial calculations indicate that approximately 122 additional 70-W HPS fixtures will be required to produce the same amount of illumination. This estimate will include the upgrade of a total of 315 new 70-W HPS fixtures (193 replacements and 122 new). The results of the estimate are shown in Table 3. A more detailed account may be seen in Appendix A. Estimate 2: Achieving Adequate Lighting The previous estimate calculated the cost of using 70-W HPS fixtures instead of 100-W HPS restricted breathing fixtures to produce equivalent illuminance. While this gives a good idea of the average savings, it may not be how a design would be determined. The following estimate is more conservative. THE PERMISSIBLE TEMPERATURE OF THE PART OF A LUMINAIRE THAT COMES IN CONTACT WITH SURROUNDING GASES RESTRICTS ITS POWER RATING. Using sound engineering judgement, new fixtures were placed so that the lighting was evenly distributed and adequate for the area. Adequate lighting will be defined as at least 5 fc. at ground in general areas and 10 fc. at ground in areas were tasks are performed, such as pump rows and switch racks. To meet the requirements, 42 new fixtures will be required. The estimated lengths of conduit and conductors were taken from plot plans. This estimate will aid in drawing strong conclusions about the savings that result from using restricted breathing technology. The estimated cost is shown in Table 4. A more detailed account may be seen in Appendix A. The reader should keep in mind that this system produces less illumination than lighting the area with 100-W HPS fixtures. The installation of 235 (193 existing and 42 new) 70-W fixtures produces only 75% of the lumen output that W fixtures produce. APPENDIX A (continued) 36 TABLE A-2. DETAILED ESTIMATE OF LIGHTING UPGRADE WITH 70-W NONRESTRICTED BREATHING FIXTURES TO PROVIDE EVEN AND ADEQUATE LIGHTING. US$ per Total Material MHU Total US$ per Total Labor Total Cost, Description Units Qty. each Cost, US$ per unit MHU MHU Cost, US$ US$ 70-W HPS EA 235 $ $47, $82.00 $57, $105, Fixture 70-W Lamp EA 235 $7.50 $1, $82.00 $4, $6, in Conduit 100 ft 1.15 $ $ $82.00 $1, $1, in Conduit 100 ft 2.7 $ $ $82.00 $3, $4, AWG 1/C 1,000 ft 1.8 $ $ $82.00 $1, $1, V Termination EA 470 $1.00 $ $82.00 $5, $6, AWG 12 Wire Pull 100 ft $82.00 $2, $2, Unions EA 366 $8.00 $2, $82.00 $4, $7, Conduit Boxes EA 122 $29.50 $3, $82.00 $5, $8, (GUAT) Epoxy EA 122 $5.00 $ $82.00 $1, $2, Compound Engineering EA $ $9, $9, Overhead EA 1 $7, $7, and Profit Total $163,885.16

7 Case Study: Upgrade with Restricted Breathing This section is an account of the completed lighting upgrade project. The design and construction of this project took place in All reported costs are taken directly from accounting records. It is common practice at this facility to replace 150-W incandescent luminaires with 100-W HPS luminaires when performing lighting upgrades. This effectively increases the lumen output. A 100- W HPS ballast requires an additional 30 W. Since the load of the incandescent was 150 W, switching to a load of 130 W was convenient and required no redesign of the power supply system. Products and Services In this case, the company outsourced labor to a local electrical contractor. The lowest competitive bid determined the contractor. An outside engineering company was hired to complete the detailed engineering and drafting. The company s electrical engineer and designer also committed their time to the project. The total reported cost of this project includes the following: cost of materials service from outside contractors consultation from company staff. Total Expenses Table 5 shows an itemized list of goods and services purchased for the completion of the project. New Construction Savings The savings of a lighting upgrade in an existing installation have been demonstrated. In this section, the savings that will result from using restricted breathing technology in a new construction will be demonstrated. One can imagine, for example, that a company desires to build a new process unit having an area classification of Class I, Division 2 with a temperature rating of T3. To give an idea of how common this type of T-rating is, the following products require a T3 rating [7]: jet fuel heating oil kerosene n-hexane fuel oil. The case discussed earlier had existing infrastructure that limited replacement to no more than 150-W loads. LIGHTING FIXTURES REQUIRE ROUTINE MAINTENANCE, SUCH AS CLEANING AND LAMP REPLACEMENT. These constraints do not exist in a new construction project. Therefore, recalling from Table 1, the maximum allowable 150 W-HPS fixtures (restricted breathing) will be used. Scope The new construction area is ft, for a total of 200,000 ft 2. The design should produce approximately 10 lumens/ft 2. This will provide adequate lighting after considering derating factors. The total design illuminance for the area is 2,000,000 lumens. According to the manufacturer s photometric data, TABLE 4. ESTIMATE 2: 42 ADDITIONAL FIXTURES. Description Material Cost Labor Cost Total Cost Estimate 2 US$65, US$97, US$163, TABLE 5. CASE STUDY. Description Qty Cost per Each Total 100-W Lamp 193 US$8.75 US$1, W Fixture w/globe and 31 US$ US$7, Guard 100-W Fixture w/angle 61 US$ US$14, Reflector 100-W Fixture w/dome 48 US$ US$11, Reflector 100-W Fixture w/compact 53 US$ US$13, Refractor Company Engineering 30 US$75.00 US$2, Contract Engineering 1 US$10, US$10, Electrical Contractor a 1 US$61, US$61, Total Expenses US$124, a The electrical contractor s fee included transportation, management, tools, wiring, and other equipment. TABLE 6. QUANTITY OF FIXTURES NEEDED AND TOTAL LOAD. Fixture Type Quantity Total Load (kw) 70 W W TABLE 7. NEW CONSTRUCTION: ESTIMATE 1. Description Material Cost Labor Cost Total Cost New Construction US$163, US$365, US$528, (70 W) 37

8 TABLE 8. NEW CONSTRUCTION: ESTIMATE 2. Description Material Cost Labor Cost Total Cost New Construction US$86, US$170, US$256, (150 W) is protected by a 20-A circuit breaker. Considering future installations, each circuit will be designed to carry no more than 50% of its maximum load of 16 A or 8 A. The following calculation shows that 35 circuits will be needed: each 70-W HPS fixture produces an output of 5,800 lumens and each 150-W HPS fixture produces an output of 15,960 lumens. The total fixtures needed and their cumulative loads are shown in Table 6. Estimate 1: System Using 70-W HPS A 70-W HPS fixture, including the ballast, has a total load of 91 W. At 120 V, each fixture draws 0.76 A. The area is divided into four sections. Each section will contain a single-phase 480-V to 120/240-V transformer and an explosion-proof lighting panel. Each circuit in the lighting panel 8A/circuit 10 fixtures/circuit..76 A/fixture The result is that nine circuits will be on three lighting panels, and the fourth will have eight circuits. Leaving 20% of the panel spaces as spares, 12- circuit panelboards will be needed. According to the manufacturer s datasheets, each fixture requires a starting current of 0.8 A. Each panel will require a maximum of 72 A. Using this figure, the transformer size is determined to be APPENDIX B TABLE B-1. DETAILED ESTIMATE OF NEW CONSTRUCTION USING 70-W NONRESTRICTED BREATHING FIXTURES US$ per Total Material MHU Total US$ per Total Labor Total Cost, Description Units Qty. Each Cost, US$ Per unit MHU MHU Cost, US$ US$ W HPS EA 345 $ $70, $82.00 $84, $154, Fixture 70-W Lamp EA 345 $7.50 $2, $82.00 $14, $16, in Conduit 100 ft 93.6 $ $11, $82.00 $122, $134, in Conduit 100 ft 25.9 $ $5, $82.00 $33, $39, AWG 1/C 1,000 ft 25.9 $ $6, $82.00 $25, $31, V 10 AWG 1,000 ft 6.4 $ $1, $82.00 $8, $10, C + 1 Termination EA 690 $1.00 $ $82.00 $8, $9, AWG 12 Unions EA 1035 $8.00 $8, $82.00 $12, $21, Conduit Boxes EA 345 $29.50 $10, $82.00 $14, $24, (GUAT) 30-A Circuit EA 4 $ $3, $82.00 $5, $8, Breaker 10-kVA EA 4 $ $3, $82.00 $7, $10, Transformer 12 Circuit EA 4 $3, $13, $82.00 $7, $21, Panelboard Epoxy EA 345 $5.00 $1, $82.00 $4, $5, Compound Engineering EA $ $15, $15, Overhead EA 1 $25, $25, and Profit Total $528,634.10

9 (72A) (120V) = 8.6 kva. The next higher standard transformer size of 10 kva is chosen. The 480-V side of the transformer will see up to 21 A, requiring 10 AWG copper conductor. Each transformer will need a 30-A circuit breaker in the distribution panel. Table 7 shows the result of the estimate. A more detailed account may be seen in Appendix B. Estimate 2: System Using 150-W HPS A 150-W HPS fixture has a load of 188 W, with an operating current of 1.7 A and a starting current of 2.0 A. Again, the area is divided into four sections, each containing a single-phase 480-V to 120/240-V transformer and 120-V lighting panel. Using the previous criteria, 25 circuits will be required TABLE 9. SUMMARY. Cost Without Cost with Restricted Restricted Percent Project Breathing Breathing Savings Reproducing US$238, US$124, % Illuminance Even and US$163, US$124, % Adequate Lighting New Construction US$528, US$256, % 8A/circuit 1.7A/fixture 5 fixtures/circuit. Six circuits will be on three lighting panels, and the fourth will have seven circuits. Panelboards APPENDIX B (continued) TABLE B-2. DETAILED ESTIMATE OF NEW CONSTRUCTION USING 150-W RESTRICTED BREATHING FIXTURES US$ per Total Material MHU Total US$ per Total Labor Total Cost, Description Units Qty. each Cost, US$ per unit MHU MHU Cost, US$ US$ 150-W HPS EA 125 $ $34, $82.00 $30, $65, Fixture (nr) 150-W Lamp EA 125 $11.75 $1, $82.00 $5, $6, in Conduit 100 ft 44.1 $ $5, $82.00 $57, $63, in Conduit 100 ft 9.4 $ $1, $82.00 $12, $14, AWG 1/C 1,000 ft 9.4 $ $2, $82.00 $9, $11, V 10 AWG 1,000 ft 6.4 $ $1, $82.00 $8, $10, C + 1 Termination EA 250 $1.00 $ $82.00 $3, $3, AWG 12 Unions EA 375 $8.00 $3, $82.00 $4, $7, Conduit Boxes EA 125 $29.50 $3, $82.00 $5, $8, (GUAT) 30-A Circuit EA 4 $ $3, $82.00 $5, $8, Breaker 15-kVA EA 4 $ $3, $82.00 $7, $10, Transformer 10 Circuit EA 4 $3, $13, $82.00 $7, $21, Panelboard Epoxy EA 125 $5.00 $ $82.00 $1, $2, Compound Engineering EA $ $11, $11, Overhead EA 1 $12, $12, and Profit Total $256,

10 with ten breaker spaces will be required to leave an appropriate amount of spares. Each panel will require a maximum of 70 A, again requiring a 10-kVA transformer. Table 8 shows the results of this estimate. A more detailed account may be seen in Appendix B. Other Savings In this section, some of the less obvious advantages of using restricted breathing are discussed. Power The first estimate discussed the project designed to produce equal lighting with nonrestricted breathing has a power consumption of 28.6 kw. The actual installation, using restricted breathing, consumes 25 kw. At US$0.04/kWh (kilowatt-hour), in this situation using restricted breathing saves US$ yearly. In the new construction, the system using 70-W nonrestricted breathing fixtures requires 31.4 kw. In comparison, the system using 150-W restricted breathing fixtures requires 28.2 kw, for a total savings of US$ per year. Maintenance Lighting fixtures require routine maintenance, such as cleaning and lamp replacement. A smaller number of fixtures will require fewer hours to maintain. Fewer lamps will need to be purchased for replacement. High density discharge (HID) lamp disposal, an additional expense, will be required less often. Elevation In the designs within this article, the fixtures were located between 7 and 12 ft above grade. A ladder is appropriate for this installation. At higher altitudes, scaffolding, a scissor lift, or some other means of elevation is required. Add to the equipment cost the time it takes workers to raise and lower the platform to retrieve tools and take breaks. In general, productivity decreases as the workspace gets higher. Requiring less fixtures overall will reduce labor costs. Safety Using equipment that is properly rated for the area classification increases safety by eliminating the risk of explosions. Another safety improvement using restricted breathing lighting is due to simple probability. Fewer luminaries in an area require fewer manhours to complete. The less time an employee spends on a ladder or platform, or working with power tools, THE RECENTLY DEVELOPED RESTRICTED BREATHING TECHNOLOGY ALLOWS THE INDUSTRY TO INSTALL HIGHER-WATTAGE LUMINAIRES IN T3-RATED AREAS, WHILE MAINTAINING AREA CLASSIFICATION REQUIREMENTS. the less chance he or she has of sustaining an injury. Electrical Putty Restricted breathing prevents gases from entering the fixture. Electrical putty is usually used for this purpose. The nonsparking restricted breathing fixtures eliminate the labor and material costs associated with electrical putty. Conclusions The recently developed restricted breathing technology allows the industry to install higher-wattage luminaires in T3-rated areas, while maintaining area classification requirements. Lighting projects involving restricted breathing cost less to install in classified areas with T3 ratings than projects not using restricted breathing. If the desire is to increase lumen output, or replace outdated lighting, restricted breathing fixtures save money and time. Table 9 summarizes the estimated savings demonstrated in this article. Acknowledgments Special thanks to Paul Babiarz, Bill Bell, Jeff Yezdimer, and Bob Young for their valuable support and contributions. References [1] National Electrical Code, NFPA 70, [2] P.J. Schram and M.W. Earley, Electrical Installations in Hazardous Locations. Quincy, MA: National Fire Association, pp , [3] Cooper Crouse-Hinds Product Catalog 6000 Ed., Cooper Industries Inc., Syracuse, NY, pp. 725, [4] Lamp Specification and Application Guide, SAG-100, Phillips Lighting Company, Somerset, NJ, pp. 98, [5] G. Brady, M. Throckmorton, M. Walton, and M. Cole, Lighting and control advancements for hazardous (classified) areas in industrial facilities, in Proc PCIC Conf., pp , [6] Electrical Installations in Petroleum Processing Plants, API Recommended Practice 540, 4th ed. Quincy, MA: American Petroleum Institute, pp , [7] Recommended Practice for the Classification of Flammable Liquids, Gases or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, NFPA 497, Robert C. Potter Jr. (bob.potter@crouse-hinds.com) is with Cooper Crouse-Hinds in Oxford, Pennsylvania. Donna Lee Hodgson is with the Maintenance and Integrity Organization of Shell s Exploration and Production Company in New Orleans, Louisiana. This article first appeared as Hazardous Lighting From Safety to Savings at the 2005 Petroleum and Chemical Industry Conference. 40