Understanding the Standards Surrounding Arc Flash Hazards and Arc Resistant Equipment

Transcription

1 Understanding the Standards Surrounding Arc Flash Hazards and Arc Resistant Equipment 1 Rev 5058-CO900E

2 This presentation contains many hidden slides that are provided for the presenters information and/or additional background on some of the topics.

3 Agenda 1. Related Electrical Safety Standards 2. Arc Flash Characteristics/Dynamics 3. Arc Resistant Equipment Rating Basics 4. Field Implementation of Arc Resistant Equipment 5. Minimizing Exposure to Arc Flash Hazards 3

4 Agencies & Documents that Govern Electrical Safety Establishes the general enforcement & guideline policies to assure safe and healthy working conditions Provides guidance for the safe installation & wiring of equipment by Qualified Electrical Workers A standard to protect all users from electrical hazards in the workplace while giving guidance to employers as to the How to Forum for standards development and for consistent engineering practices

5 State and Federal Regulations Occupational Safety & Health Act USA OSHA 1910 Subpart S Electrical Safety Related Work Practices Title 29 (CFR), Part Design Safety Standards for Electrical Systems Title 29 (CFR), Part In Canada; Occupational Health & Safety Acts Each individual Canadian Province has their own no common act 5

6 Installation Codes & Standards National Electrical Code 2014 (NFPA 70) Canadian Electrical Code 2012 (C22.1) Electric Codes (NEC/CEC) and other safety codes historically, have been primarily concerned with protection from fire, electrocution and shock hazard Arc flash hazards not directly mentioned until 2002 On-going refinements have significantly changed some of these standards regarding arc flash! They now contain direct linkage to other safety standards 6

7 NEC Recognizes Arc Flash Hazards In 2002, NEC added Article and reinforced arc flash protection marking of equipment Flash Protection: switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn qualified persons of potential electric arc flash hazards Arc flash hazard marking is requirement to be applied by the user or [applied in factory*] for each specific application Users must establish a consistent labeling philosophy in support of their electrical safety program Ref. new wording in NFPA-70E-2012, Sec (C) listing revised information to be included on arc flash labels updated in updated in the 2014 edition! the 2014 edition! 7

8 Electrical Safety Standards NFPA 70E NFPA 70E, the Standard for Electrical Safety in the Workplace 2012 Electrical Safety, including Arc Flash Hazards, are a focus of all users Intended to help protect employees from electrical hazards Provides the framework for an effective Electrical Safety Program Specifics related to better approaches to electrical safety Ever increasing focus on electrical safety and Electrical Safety Programs! 8

9 Canadian Electrical Safety Standard - CSA Z462 Canadian Standards Association - Z462 CSA-Z462 was developed in parallel with and harmonized to NFPA 70E-2009 References directly to the Canadian Electrical Code (CEC) and is consistent with OHSA data Z is aligned to NFPA-70E-2012 and the CEC 9

10 Adding Clarity to the Labeling Requirements Defined by NEC 2014 Section

11 Adding Clarity to the Labeling Requirements Defined by NEC 2014 Section Defined by NFPA-70E Sec (C) 11

12 Adding Clarity to the NFPA-70E Labeling Requirements Labels compliant to NFPA-70E-2012 Section (C) MUST include at least ONE of the following: Available incident energy and the corresponding working distance OR, Minimum arc rating of clothing OR, Required level of PPE OR, Highest Hazard/Risk Category (HRC) for the equipment Plus 1. Nominal System Voltage 2. Arc Flash Boundary Labels applied prior to Sept. 30, 2011 are acceptable if they contain the available incident energy or level of PPE required

13 Understanding the Regulatory Framework Interplay between OSHA's electrical safety regulations, the NEC, and NFPA-70E should be the basis of your overall electrical equipment systems and safety programs OSHA's electrical safety regulations draw heavily on the consensus standards like NEC and NFPA-70E, but there are some important distinctions Compliance with the NEC and NFPA-70E does not always equate to full compliance with all OSHA regulations! OSHA 1910 Subchapter S = Shall NFPA-70E = How & When 13

14 OHSA Standards Take Precedence Many electrical safety programs based only on NFPA 70E Some don t include the applicable OSHA electrical requirements OSHA requirements & regulations always take precedence in areas where OSHA regulations set a more stringent requirement As federal regulations, they have the force of law 14

15 Ignoring the importance of NFPA 70E Some say NFPA 70E is not an OSHA Requirement! It is not the law so neither of these facts matter! "Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body." (29 CFR (a)) OSHA requires employers to protect employees from "recognized hazards" (General Duty Clause) and steps must be taken specifically to address electrical hazards defined in 29 CFR (a) 15

16 The Importance of Electrical Safety 5-10* arc flash incidents still occur each day in the USA Continued focus on personal injuries or fatalities Prevent potential loss to organizations through, Loss of skilled manpower Litigation fees Higher insurance costs Loss of company morale Production losses OHSA Fines Employee moral *- Source CapShell Inc. OSHA inspector will reference keeping workers safe around electrical hazards without referencing any specific standard(s) 16

17 How are OHSA and NFPA-70E linked? Industry consensus standards can be evidence that there is a hazard for which PPE is "necessary." While the NFPA 70E consensus standard has not been adopted as an OSHA standard, it is relevant as evidence that arc flash is a recognized hazard and that PPE is necessary to protect against that hazard. OHSA An flash hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. The analysis shall determine the Flash Protection Boundary and the personal protective equipment that people within the Flash Protection Boundary shall use OHSA & p/o. NFPA-70E Failure to protect workers will result in OHSA using it s authority to prosecute to the fullest extent of the law, based on these premises 17

18 Basic Compliance to NFPA-70E requires 1. Establishing and Auditing an Electrical Safety Policy with Clearly Defined Responsibilities 2. Perform an Arc Flash Hazard Analysis and Proper Labeling of the Electrical Equipment 3. Providing Appropriate and Adequate PPE including Insulated Tools 4. Training, Re-training & Maintaining a Training Audit Trail for All Workers 5. Properly Maintaining Equipment and Keeping Records 6. Reviewing and Installing various Engineered Solutions for reducing or controlling Arc Flash Hazards (inc. AR equipment) 18

19 New Compliance Requirements in NFPA 70E-2012! Your Electrical Safety Program must be audited on a cycle of three years or less [70E-2012, Sec ] An electrical system study or review (arc flash study) must be completed every five years or less [70E-2012, Sec ] Regular Safety Training and Assessments for all* electrical workers every 3 years or less [70E-2012, Sec (D)] You must be able to prove compliance to these points if OHSA audits your sites 19

20 But we use the tables in NFPA-70E to define the hazard Tables are GENERAL GUIDELINES NOT specific to your location, your equipment or your equipment s configuration Look for the fine print or general notes for the tables- tables are based on fundamental assumptions about the available short circuit currents, overcurrent device clearing times and working distances From Table 130.7(C)(15)(a) A qualified person must verify that the electrical system fault current and the protective device settings are both equal to or lower than the values assumed when the tables were developed NFPA-70E tables are subjected to misuse if they are applied without knowledge -- putting employees at risk! 20

21 PPE Clothing Testing Standards have also Changed Consistency of selection of PPE to the terminology in applicable ASTM and NFPA standards Differentiates Arc Flash rated clothing from flame-resistant clothing Arc flash rated PPE tested for protection against the thermal effects of an arc flash Arc-rated clothing is flame resistant but not all flame-resistant clothing is Arc Rated 21

22 Common NFPA-70E* Misconception Some assume it is an equipment design specification 90.1 Purpose. The purpose of this standard is to provide a practical safe working area for employees relative to the hazards arising from the use of electricity. NFPA-70E 2012 Existing, nationally recognized, product design standards for LV and MV controls Do Not address any specifics related to arc fault/resistance performance; e.g. UL 845, for low voltage motor control centers UL 347, for medium voltage control centers *Z-462 has similar references as in NFPA-70E 22

23 Electrical Safety Standards NFPA 70E What s new in NFPA 70E 2012, Arc Resistant Table 130.7(C)(15)(a) Hazard Risk Category (HRC) Classifications Arc Resistant equipment is now referenced Arc resistant equipment reduces the HRC= 0* for All doors must be closed * * Rockwell Automation provides an enhanced level of protection in our MV MCC products! Recognition of AR equipment now included in the 2012 version 23

24 Agenda for Today 1. Related Electrical Safety Standards 2. Arc Flash Characteristics/Dynamics 3. Arc Resistant Equipment Rating Basics 4. Field Implementation of Arc Resistant Equipment 5. Minimizing Exposure to Arc Flash Hazards 24

25 Arc Flash Dynamics 25

26 Arc Flash/Blast Shrapnel Up to 35,000 F Molten Metals Intense Light Sound/ Pressure Waves Copper Vapors (Expansion rate 67,000 times) Intense Heat 26

27 Causes of Arc Flashes Human Factors Accidental touch Dropping or misplacement of tools & other parts Improper installation practices Mechanical Closing into faulted lines Loose connections 27

28 Causes of Arc Flashes Environmental Dust Liquid & moisture infiltration Impurities Corrosion at contact surfaces Failure of insulating materials Snapping of leads due to abnormal force human, rodents or birds 28

29 Agenda for Today 1. Related Electrical Safety Standards 2. Arc Flash Characteristics/Dynamics 3. Arc Resistant Equipment Rating Basics 4. Field Implementation of Arc Resistant Equipment 5. Minimizing Exposure to Arc Flash Hazards 29

30 What is Arc Resistant Equipment? Controls the exposure and release of the dynamic elements associated with an internal arc flash Defined by the level to which these elements are: Extinguished or Controlled Prevented from seriously injuring personnel Prevented from propagating Generally protection applies only when all equipment doors are closed* and latched Our MV ArcShield products provide an enhanced level of arc resistant capabilities Testing must be done to validate the level of protection defined by the Accessibility Level 30

31 Arc Resistant Equipment Considerations A fundamental approach to Arc Flash safety must include all personnel, electrically qualified and non-qualified personnel* Arc faults can occur during normal operation without a specific human action and affect someone minding their own business in the proximity of the equipment Potential victims can be anyone; electrically qualified or not Simply walking by the equipment or sweeping the floor in the equipment room In the wrong place at the wrong time Arc resistant equipment addresses arc flash hazards during normal operation 31

32 Common Arc Resistant Testing Guides & Standards CSA C22.2 NO Evaluation Methods for Arc Resistance Ratings of Enclosed Electrical Equipment EEMAC G Procedure for Testing the Resistance of Metal-Clad Switchgear under Conditions of Arcing Due to an Internal Fault IEC AC Metal-Enclosed Switchgear and Controlgear for Rated Voltages Above 1 kv and up to and Including 52 kv, Annex A - Internal Fault IEC Enclosed low-voltage switchgear and controlgear assemblies Guide for testing under conditions of arcing due to internal fault IEEE C "IEEE Guide for Testing Metal-Enclosed Switchgear Rated Up to 38 kv for Internal Arcing Faults Many global guides and standards for AR equipment.. Compliance to one does not mean compliance to the others

33 IEEE C Testing Guide IEEE C IEEE guide for testing metalenclosed switchgear rated up to 38 kv for internal arcing faults Primarily a medium voltage testing guide Expanded to include some low voltage switchgear components Defines test criteria and compliance assessment Defines the levels of arc flash protection Sets expectations of arc resistance performance related to the interaction with personnel IEEE C is the most recognized North American Testing Guide that applies to MV and some LV equipment 33

34 Arc Resistant Equipment Considerations Arc resistant equipment must been tested to at least one of these relevant testing guides or standards Equipment supplier should be able to provide documentation to support their performance claims Certification Letter 3 rd party Letter of Attestation 34

35 Arc Resistant Equipment Considerations Passing* an arc test generally means: Doors and covers do not open (bowing allowed) No parts are ejected from the equipment Hot gases are not ejected in protection zones Cotton test indicators must not ignited or be perforated (150 g/m 2 approximates typical industrial work clothes) No burn through of the exterior of the structure (in the applicable zones for the accessibility level) Grounding connections remain effective *Per IEEE C (varies by guide/standards) 35

36 Accessibility Types Type A Type A Front only EEMAC Type B Front, back, sides Type C Front, back, sides, & compartment Accessible to authorized personnel IEC Type B Accessible to general public Type C Pole top equipment Type 1 Front only IEEE Type 2 Front, back, sides Suffix B LV controls compartment protection

37 IEEE Levels of Arc Resistant Protection Accessibility Type Type 1 Front of structure Type 2 Perimeter of structure Suffix B Perimeter of structure even when LV control panel door open Preferred MV Accessibility Type should be Type 2B Top View

38 IEEE Accessibility Type 1 2 meters

39 IEEE Accessibility Type 1

40 IEEE Accessibility Type 2 2 meters

41 IEEE Accessibility Type 2B 2 meters

42 Arc Resistant Rating Choices -- The Basics Duration Rated The equipment s ability to withstand a specific level of arcing current for a specified duration Time and current based Independent of any other protective devices Device Limited Rated A protective device is used to limit the current and/or duration of an arcing fault No specific duration may be stated 42

43 Arc Resistant Rating Basics -- Duration Based 43

44 Arc Resistant Vendor Nameplate Data Duration Rated Name includes Accessibility type Standard/Guide used for validation testing Stated test current States test and duration Applied at the factory by equipment manufacturer * -The maximum value of RMS symmetrical prospective current applied for arcing fault testing for the rated arcing duration 44

45 Arc Resistant Rating Basics- Device Limited Rating 45

46 Arc Resistant Vendor Nameplate Data Device Limited Nameplate includes Accessibility type Maximum S.C.C. Protective Device data Applied at the factory before the equipment ships * -The maximum value of RMS symmetrical prospective current applied for arcing fault testing for the rated arcing duration 46

47 Arc Resistant Rating Basics So how do you know what rating is the correct rating for your system? Consider the short circuit current level at the point of the equipment s use How long do you think your system can sustain an arcing fault? The longer the time the greater the release of energy The longer the time a higher degree of internal damage will ensue Where your coordination study comes in to play You will need a short circuit and arc flash study completed to know the risks 47

48 Some Items to Consider in Writing your Specifications Duration Rated or Device Limited? What arc current rating and what duration? 20kA- 100ms 30kA- 200ms 40kA- 500ms Etc. What Accessibility Type works best for your Safety Program? Will there be a mix of equipment from various vendors? Can I still get top & bottom entry cables? Some vendors cannot support both 48

49 IEEE Guide for Performing Arc- Flash Hazard Calculations A guide & method for performing the calculations for arcflash incident energy and arc-flash boundaries in threephase AC systems to which workers may be exposed Requires the data from a system Short Circuit & Coordination Study NFPA 70E does not mandate calculations be performed only using the IEEE 1584 methods- other methods can be used How valid is your present system coordination/arc flash study? NFPA-70E-2012 sec states it shall be reviewed periodically, not to exceed 5 years! Mandated through NFPA-70E - auditable by OHSA 49

50 So what are the steps? Arcing Fault Currents (Incident Energy) 3 Phase Bolted Fault Current Device Operating Times 50

51 Agenda for Today 1. Related Electrical Safety Standards 2. Arc Flash Characteristics/Dynamics 3. Arc Resistant Equipment Rating Basics 4. Field Implementation of Arc Resistant Equipment 5. Minimizing Exposure to Arc Flash Hazards 51

52 Arc Resistant Equipment Considerations Significant deviations in the cabinet design may not be possible if arc resistant integrity is to be maintained Some typical non-arc resistant factory-installed options may not be available Installation practices need to be more stringent Any field modifications must be approved by the manufacturer You don t want to compromise the equipment's ability to control an arc flash event It is critical to maintain the arc resistant capability of arc resistant equipment - as purchased 52

53 Installation Considerations Arc resistant equipment vendors can help by providing appropriate information for: General equipment installation procedures Equipment dimensions, including plenums/chimneys (if required) Plenum/Chimney installation requirements (if required) Overhead clearance requirements Site-specific considerations 53

54 Installation Considerations More preparatory planning required Where is the equipment to be installed? Existing or new room/building? Overhead clearances require in addition to wire trays? For MV equipment, what is the overhead clearance required to accommodate a plenum or arc ducting system? Are there existing cables, conduits or HVAC ducting in the area? Will there be non-arc resistant equipment in the same area? How will the differences be identified to workers? 54

55 Installation Considerations Where will the energy from any MV arc blast be directed? Within the building assumes an area can be made inaccessible to personnel and no flammable materials are present Externally is generally preferred Environmental barriers to restrict the entry of weather or vermin must be considered 55

56 Installation Considerations If the arc gases are going to be released into an MCC room or building, it must be designed to withstand: Overpressure of up to psi, on a transient basis The effects of hot gases, flames and toxins released into the room (i.e. non-flammable construction materials are required) Rapid ventilation of toxic gases 56

57 Installation Considerations How will the cable/conduit enter the arc resistant structure? Access for top entry may be limited Some vendors can t support top entry Interface point for the arc resistant structure and cables entering power cell should be treated similar to the boundary between a location that is hazardous and one that is not For short conduit runs they may need to be packed to limit the egress of arc energy into another area 57

58 Installation Considerations Has your installation contractor ever installed arc resistant equipment before? Make sure your installation specifications outline the equipment design and installation requirements Inform your contractor that no holes can be cut without approval Insure all cover plates are reinstalled per the manufacturers recommendations Don t compromise the safety integrity of your investment Rockwell Automation can support your installation needs 58

59 Routine Maintenance How often are you maintaining your equipment? Are you testing and maintaining your protective devices- especially older units Are you maintaining your breakers per the manufacturers recommendations? Some of your personnel protection may be dependent on a protective devices or CBs opening time Over 30% of low and medium voltage power circuit breakers tested, that have been in service for more than 24 months in industrial applications, will not perform to specification when as found trip tests are performed. data from a breaker service group - results compiled from >2500 breakers 59

60 Benefits of Arc Resistant Controls Arc resistant equipment offers an enhanced level of safety to personnel Specify arc resistant equipment that has been tested to relevant standards and conditions Requires some additional engineering steps to successfully implement Requires more diligence for proper installation When installed per the manufacturer s instructions, arc resistant equipment performance is optimized Failure to follow these instructions may nullify the AR protection Also, you really need to determine if arc resistant products are really needed Arc resistant equipment can be a vital part of a comprehensive program for improving personnel safety 60

61 Agenda for Today 1. Related Electrical Safety Standards 2. Arc Flash Characteristics/Dynamics 3. Arc Resistant Equipment Rating Basics 4. Field Implementation of Arc Resistant Equipment 5. Minimizing Exposure to Arc Flash Hazards 61

62 Arc Flash and Other Services Rockwell Automation can provide comprehensive services to assess and enhance the Arc Flash Safety within your facilities System Short Circuit Studies Power System Coordination Studies Arc Flash Hazard/Risk Analysis Field Labeling Mitigation Services Arc Flash Program Agreements Training & Maintenance Agreements For more information, contact one of our authorized distributors 62

63 How can Rockwell Automation support your needs? Arc Resistant Controls Non-Arc Resistant Controls Evaluation of your System Requirements Propose alternative engineered solutions to reduce risk Provide fully site services for routine and emergency maintenance Rockwell Automation can provide innovative solutions in support of your Electrical Safety Program Requirements 63

64 kv NEMA ArcShield Arc Resistant Controls 400A/800A FVNR One & Two High Solid State Starters, SMC Flex Reversing Starters Feeder Load Break Switch PFCC units Incoming and aux. units Broadest Range of MV Arc Resistant Control Products compliant to IEEE C Type 2B accessibility level 64

65 MV ArcShield NEMA Arc Resistant Controllers Tested to IEEE C Type 2B Accessibility 40 ka 7.2 kv), for ½ second Personnel are shielded at the front, rear and sides of enclosure Arc Resistance is maintained even with LV doors open Plenum or Chimney systems used to safely direct arc flash energy away from personnel 65

66 Medium Voltage OneGear IEC Arc Resistant Controls ONEGear IEC 7.2 kv Motor Control Center Arc resistant to IEC kV, ½ sec. AFLR Only 350mm (13.8 ) wide ONEGear IEC 15 kv Controlgear Arc resistant to IEC kv, ½ sec. AFLR 15 kv electronic soft starters now available IEC Arc Resistant Products for your global requirements 66

67 Minimize Risk from Arc Flash Hazard ArcShield NEMA and IEC Low Voltage Motor Controls CENTERLINE 2100 Low Voltage NEMA Motor Control Center with ArcShield First arc resistant NEMA low voltage MCC IEEE C Type 2 Accessibility 100ms, to 480V (duration limited) <65kA* 1200A fuse or CB to 600V (*Device Limited, specific 1200A or less limiting device) CENTERLINE 2500 Low Voltage IEC Motor Control Center with ArcShield Personnel and assembly protection per IEC 61641: ms, to 480V NEMA and IEC LV Arc Resistant MCCs 67

68 CENTERLINE 2100 NEMA MCC with ArcShield CENTERLINE 2100 MCCs offer an extensive list of features to address personnel safety With an increased focus on arc flash safety, CENTERLINE 2100 with ArcShield The first and only LV MCC offering arc-resistant features Type 2 accessible (IEEE C ) enclosure provides extra protection for personnel Networkability provides for remote monitoring, configuration and troubleshooting Keeps doors closed Keeps personnel out of arc flash boundary Monitor or Diagnose remotely 68

69 CENTERLINE 2100 MCC with ArcShield Manual or Automatic Shutters Pressure Relief System Insulating Covers on Horizontal Bus Closing Plates Arc-Resistant Latches on All Doors Copper Vertical Ground Bus and Heavy Duty Ground Stab on Plug-in Units Arc Resistant Baffles 69

70 CENTERLINE 2500 MCC with ArcShield Pressure Relief System Arc-resistant Latches Automatic Shutters Insulating Covers on Horizontal Bus Closing Plates Non-vented enclosure Copper vertical ground bus on withdrawable structures Heavy duty ground stab on withdrawable units 70

71 Many Other Safety Features Available for CENTERLINE LV MCCs Covers and Barriers Through the Door Viewing Windows Through the Door Network Connections High Visibility Yellow Door for Main Door Mounted Voltage Detection Infrared Sightglass for Thermal Inspection DeviceNet Programmer 193-DNCT SafeZone Laser Scanner Fiber Optic Arc Detection/Arc Clamping Systems 71

72 Minimize Exposure to Hazards with the New SecureConnect Option Reduce Electrical Shock and Exposure to Harmful Voltages Verify removal of power in the MCC unit with a patented multi-point validation system Two sets of shutters for increased electrical isolation Provides redundant indication for disconnect position No impact to space factor of units Available on standard and ArcShield MCC Copyright 2011 Rockwell Automation, Inc. All rights reserved. 72

73 Minimize Exposure to Hazards with SecureConnect Remote Operator Option Allows you to Connect and Disconnect unit stabs from outside the arc-flash boundary Provides indication for safe entry back inside Arc Flash boundary Allows for operation up to 30 feet away Attach the remote operator mechanism to the front of the SecureConnect unit To 120 VAC (Confidential For Internal Use Only) Copyright 2011 Rockwell Automation, Inc. All rights reserved. 73

74 Minimize Exposure to Hazards with ArcShield & IntelliCENTER Technology Monitor, configure & troubleshoot remotely Enhanced network capabilities IntelliCENTER software allowing for remote monitoring, configuring and troubleshooting remotely - No need to be near the equipment Monitor, configure & troubleshoot remotely 74

75 Summary What is the purpose of all of these new standards, regulations and arc resistant control products? Enhanced Personnel Safety Create a safer work environment for all Ultimately reduce the number of injuries and fatalities caused by electrical hazards Electric Shock Arc Flash Arc Blast Rethinking Distribution networks Design out some of the risks Rockwell Automation has the products, the knowledge and the global infrastructure to help you with all of your safety and automation needs 75

76 Thank You! Let us tell you more about our complete line of Rockwell Automation NEMA and IEC arc resistant solutions! 76

77 Questions Follow ROKAutomation on Facebook & Twitter. Connect with us on LinkedIn. Rev 5058-CO900E 77

78 Adoption of the NEC As of Nov. 11, 2013

79 Global Arcing Resistant Equipment Testing Standards EEMAC G14-1; Procedure for Testing the Resistance of Metal-Clad Switchgear under Conditions of Arcing Due to an Internal Fault (Canadian Standard) IEC ; AC Metal-Enclosed Switchgear and Controlgear for Rated Voltages Above 1 kv and up to and Including 52 kv, Annex A - Internal Faults (Global Standard mostly viewed as European) IEEE C ; IEEE Guide for Testing Metal-Enclosed Switchgear Rated Up to 38 kv for Internal Arcing Faults (North American Standard) Mostly related to MV switchgear/mccs and some metal-enclosed lowvoltage power circuit breaker switchgear Does not cover most LV equipment or panel boards Does not directly cover 480/600V motor controls**