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Home My WebLink AboutAVAILABLE FAULT CURRENTS - 23-00693 - Sterling Medical - New Commercial BldgWeb Sites: https://www.rockymountainpower.net/working-with-us/business-customers/arc-flash-fault-current.html https://www.pacificpower.net/working-with-us/business-customers/arc-flash-fault-current.html Revisions Arc Flash Arc flash analysis determines the arc flash boundary, the incident energy at working distance, and the level of personal protective equipment required for personnel to work within the arc flash boundary. The Occupational Safety and Health Association (OSHA) and National Fire Protection Association (NFPA) mandate arc flash analysis to determine the Hazard Risk Category (HRC) which establishes the level of Flame Resistant (FR) clothing required for personal protection. NFPA 70 E, Article 130.5 states, "The arc flash hazard analysis shall be updated when a major modification or renovation takes place, and is to be reviewed periodically, not to exceed 5 years. Secondary Fault Current NFPA 70 (National Electric Code), Article 110.24 requires electrical service panels be labeled with available fault current. This helps ensure properly sized equipment is installed, reducing the probability of damage caused by electrical faults. Electrical power system fault duties tend to increase as systems are modified. Rocky Mountain Power and Pacific Power'spolicy is to provide secondary fault current at the transformer assuming an infinite source. Tables found in tab "Fault Current Infinite Bus" provide these values. Transformer size must be confirmed. Customers must submit*the following information on the "Request Form": · Facility Point Numbers(s) see Fig#1 on "Request Form" tab · Service Voltage (240/120, 208Y/120, 480Y/277) · Phase (Single-Phase, Three-Phase) * Call 1-888-221-7070 for "Request Form" submittal information Arc Flash Request Upon receipt of completed "Request Form" customer is provided: · System Impedance on primary side of distribution transformers · Average transformer impedances · Transformer fusing information Secondary Fault Current Request Upon receipt of completed "Request Form" customer is provided: · Transformer size · Fault Current Infinite Bus table Disclaimer Rocky Mountain Power and Pacific Power recommend customers de-energize electrical conductors when contact or faults are possible. In providing the information contained herein, the recipient acknowledges and understands that Rocky Mountain Power and Pacific Power provides this information based on the information in its files and other information available to it at the time of the request. The data will change over time based on changes in load and other dynamic elements of Rocky Mountain Power and Pacific Power's electrical system. Rocky Mountain Power and Pacific Power has not independently verified the accuracy of this information for the purposes for which it may be used by the recipient. Furthermore, recipient understands and acknowledges that Rocky Mountain Power and Pacific Power has no Commercial and Industrial Arc Flash and Secondary Fault Current Information Requests Each year Rocky Mountain Power and Pacific Power provide arc flash and secondary fault current information to electrical consultants and electricians. To ensure consistency Rocky Mountain Power and Pacific Power utilize an Arc Flash/Secondary Fault Current "Request Form". Requester Information Date of Request Company Name Contact Name Street Number City, State, Zip Main: Cell: Email address Facility Location Company Name Facility Name * Facility Point Number If possible provide a photo of the facility point tag. Please paste the photo in the cell to the right. Meter Number * Delivery Voltage * Phase * Required Information Pad Mounted Transformer Facility Point # = 05218092-173500 Figure #1: Facility Point Examples Pole Mounted Transformers Three Phase: 208Y/120V, 4-Wire Three Phase Arc Flash and Secondary Fault Current Data Request Form 11-13-2023 Scott Page 260 E Moody Rd Rexburg, Idaho, 83440 Please submit a separate request for each site by duplicating this tab. Steps: 1) Fill in "Requestor Information, 2) Right click "Request Form (Customer) tab, 3) Move or Copy, 4) Select "Request Form (Customer), 5) Check "Create a Copy", 6) OK. Complete "Facility Location" section for each site. Mailing Address scott@venturebuilders-id.com Phone Numbers Venture Builders LLC (Field Engineer sends this Form to Customer. Customer fill's out Form and returns it to Field Engineer) 208-313-0980 03106040.0171901 Rocky Mountain Power Facility Information District Substation Circuit Facility Point # Primary System Voltage Transformer Connection Transformer Size / Type 225 kVA Padmount Delivery Voltage (1) Transformer %Z Secondary Conductor (2) Secondary Length (2) impedance at meter point is provided. Protection Transformer Fusing Field Engineer Provides: Arc Flash Request: 1) System Impedance on primary side of distribution transformers 2) "Fault Current Infinite Bus" tables showing average transformer impedances 3) Transformer fusing information Secondary Fault Current Request: 1) Transformer size 2) "Fault Current Infinite Bus" tables Transformer & Service Diagram Primary System Fault Amps & Impedances For Secondary Fault current request Field Engineer provides the transformer size information only. See Fusing Tabs 12.47Y 03106040.0171901 3ph GrdWye-GrdWye If service is primary metered only the primary system (2) Secondary conductor information is provided when available. Three Phase: 208Y/120V, 4-Wire 350-AL See Fault Current Infinite Bus Tab, Table 2 (1) Voltage as confirmed by Customer 80' Site Data RXB#11 Address Chance Russell 208-479-1674Phone Number Rexburg, ID. 170 W 2nd N Service Center Field Engineer For Arc Flash request Field Engineer completes this Form and sends to Customer. Rexburg Rexburg Short Circuit Transformer Bus Current Assuming an Infinite Bus 1 Table 1: 480Y/277 Three Phase Pad Mounted Transformer Transformer kVA Stock Number % IR %IX X/R ratio Transformer %Z Calculated Fault Current (Amps) 75 4710090 1.01 2.92 2.89 1.62 5,575 Panel Rating 112.5 4700091 0.98 2.52 2.57 2.70 5,018 100 10,000 150 4700228 0.89 2.97 3.34 3.18 5,680 400 22,000 225 4700229 0.8 3.74 4.68 3.52 7,698 800 22,000 300 4700094 0.78 3.66 4.69 1.61 22,439 1600 65,000 500 7991410 0.74 3.88 5.24 1.94 31,037 3000 85,000 750 7991371 0.73 5.68 7.78 5.63 16,042 4000 85,000 1000 9174749 0.62 5.74 9.26 5.45 22,096 1500 7992507 0.69 5.65 8.19 5.46 33,083 2000 4700159 0.69 5.62 8.14 5.66 42,553 2500 9175845 0.63 5.65 8.97 5.39 55,855 Table 2: 208Y/120 Three-Phase, Pad-Mounted Transformer Transformer kVA Stock Number % IR %IX X/R ratio Transformer %Z Calculated Fault Current (Amps) 75 7991359 1.16 2.49 2.15 2.70 7,719 112.5 4700211 0.83 2.18 2.63 2.33 13,418 150 4730212 1.17 3.03 2.59 3.20 13,027 225 7991903 1.40 2.46 1.76 2.70 23,158 300 4700214 0.81 3.11 3.84 1.75 47,640 500 9175340 0.83 3.53 4.25 2.17 64,033 750 7999497 0.85 5.79 6.81 5.80 35,936 1000 8004518 0.83 5.89 7.10 5.95 46,706 Table 3: 120/240 Single-Phase, Pad-Mounted and Overhead Transformers Transformer kVA Stock Number % IR %IX X/R ratio Transformer %Z Calculated Fault Current (Amps) 10 N/A N/A N/A N/A 1.16 3,592 25 4600612 0.92 1.50 1.63 1.70 6,127 50 9162314 0.80 1.40 1.75 1.60 13,021 75 4500356 0.97 1.10 1.13 1.49 20,973 100 9161902 0.98 1.20 1.22 1.51 27,594 167 N/A N/A N/A N/A 1.55 44,892 250 4500115 0.70 2.37 3.39 2.50 41,667 333 4500116 0.67 3.11 4.64 3.20 43,359 500 4500108 0.65 2.60 4.00 2.70 77,160 Information provided by Manufacturer NEMA Short Circuit Ratings Information provided by Manufacturer Information provided by Manufacturer 1 2 Non-standard transformer Table 4: Single-Phase Overhead Transformers used to create 480Y/277 banks Transformer kVA Stock Number % IR %IX X/R ratio Transformer %Z Calculated Fault Current (Amps) 25 N/A 1.20 1.40 1.17 1.84 4,909 37.5 N/A 1.20 1.40 1.17 1.84 7,363 50 N/A 1.00 1.40 1.40 1.72 10,502 75 4500364 1.00 1.20 1.20 1.55 17,481 100 4500124 0.84 1.64 1.95 1.51 23,925 167 N/A 0.90 1.30 1.44 1.58 38,185 250 N/A N/A N/A N/A 1.70 53,128 333 N/A N/A N/A N/A 1.60 75,190 Table 5: Single-Phase Overhead Transformers used to create three phase banks 208Y/120, 240 Closed Delta, 240 Open Delta Transformer kVA Stock Number % IR %IX X/R ratio Transformer %Z Calculated Fault Current (Amps) 25 N/A 1.20 1.40 1.17 1.84 11,327 37.5 4500450 1.43 1.06 0.74 1.78 17,564 50 N/A 1.00 1.40 1.40 1.72 24,236 75 4500300 0.97 1.19 1.23 1.54 40,602 100 N/A 0.86 1.28 1.49 1.54 54,137 167 N/A 0.90 1.30 1.44 1.58 88,119 500 N/A 1.10 1.60 1.45 1.90 219,396 Table 6: 480/240 Single-Phase, Pad-Mounted and Overhead Transformers Transformer kVA Stock Number % IR %IX X/R ratio Transformer %Z Calculated Fault Current (Amps) 10 N/A 0.80%1.36%1.72 1.41%1,478 25 N/A 1.26%1.57%1.25 1.76%2,959 Information provided by Manufacturer Information provided by Manufacturer Infinite Bus assumes unlimited primary short-circuit current. The power company's distribution system is constantly changing resulting in system impedances that change over time. An infinite bus eliminates the need to constantly re-evaluate short circuit current. Information provided by Manufacturer 50 N/A 1.09%2.16%1.99 2.11%4,937 75 N/A 0.98%2.19%2.25 2.34%6,677 100 N/A 1.09%1.66%2.30 1.34%15,547 167 N/A 0.82%2.81%3.50 2.17%16,033 250 N/A 0.68%3.10%4.56 2.90%17,960 333 N/A 0.64%3.16%5.01 3.10%22,379 500 N/A 0.63%3.19%5.04 3.20%32,552 For more information on Cooper Power Bay-o-net and Isolation Links see Cooper Power Catalog. Dual Sensing Bay-o-net fuses: Cooper Power Catalog Section 240-46 http://www.cooperindustries.com/content/dam/public/powersystems/resources/library/240_Fusing/24046.pdf Isolation Links: Cooper Power Catalog Section 240-47 http://www.cooperindustries.com/content/dam/public/powersystems/resources/library/240_Fusing/24047.PDF Dual Element Bay-o-net fuses: Cooper Power Catalog Section 240-48 http://www.cooperindustries.com/content/dam/public/powersystems/resources/library/240_Fusing/24048.pdf Line-to-Grd or GrdWye-GrdWye Transformer Connections Rocky Mountain Power and Pacific Power recommend customers de-energize electrical conductors when contact or faults are possible. These tables list common transformer fuses. The purpose of these fuses is to provide a means to de-energize transformers, prevent transformer damage, and isolate damaged transformers from electrical source. These fuses do not provide protection from arc flash or electrical contact.