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NEC Article 409 UL508A Industrial Control Panels

Industrial Control Panels. Agenda. NFPA 70: National Electric Code (NEC

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NEC Article 409 UL508A Industrial Control Panels

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    1. NEC Article 409 & UL508A “Industrial Control Panels” Troy Miesse/ IE Business Development

    4. National Electric Code NFPA 70: National Electric Code (NEC®) Most states and Authorities Having Jurisdiction (AHJ) have adopted the 2005 NEC. NEC® is updated approximately every 3 years Article 409 “Industrial Control Panels” was added to the NEC® in 2005 Article 409 requires all industrial control panels to be marked with an SCCR. Empty enclosures do not have a SCCR

    5. What is a SCCR ? A Short Circuit Current Rating is the maximum current a device or panel can safely withstand for 3 AC electrical cycles (50 msec.) or while an over-current protective device operates. SCCR is usually expressed in RMS kA at the system voltage. Example: 18 kA at 480 VAC RMS is the Root Mean Squared AC current. The SCCR of a fuse or circuit breaker is the same as its Interrupting Rating (IR).

    6. NEC Article 409 Industrial Control Panel - An assembly of two or more components such as motor controllers, relays, CB’s, etc…..and related control devices Industrial Control Panels do not include the controlled equipment. Requires all industrial control panels to be marked with SCCR – This is a major addition! This addition will impact control panel builders, OEMs and end users in numerous ways: - How control panel are designed and marked - The selection of power circuit components. - The specification of preferred manufacturers. - How control panels are installed and modified.

    7. Before the NEC 2005… Only Industrial Machinery required marking for interrupting rating or SCCR of main over-current protective device Industrial control panels, HVAC control panels, motor controllers, and meter disconnects were not required to be marked with SCCR

    12. UL 508A Standard UL 508A standard is “Industrial Control Panels” The standard covers industrial control panels intended for general industrial use, operating at a voltage of 600 volts or less This equipment is intended for installation in ordinary locations, in accordance with the National Electrical Code, ANSI/NFPA 70 Supplement SB is included to help determine SCCR for Industrial Control panels by providing, among other things, default SCCR ratings for common components

    17. SCCR Calculation Example – Individual SCCR’s

    18. SCCR Calculation Example – Individual SCCR’s

    19. SCCR Calculation Example – Tested Combinations

    20. SCCR Calculation Example – Tested Combinations

    21. How to Increase SCCR Use components and approved combinations with higher rated SCCRs. Use current limiting over-current protective devices (CB/ fuses) whenever possible. Replace low interrupting rated over-current protection with higher rated ones (retrofit). According to UL 508A Articles SB3.2 and SB4.4, the SCCR of the panel cannot be greater than the interrupting rating of any over-current protective device in branch circuits or in the primary of control circuits.

    24. On-site Compliance On-site engineer provides the following information Available short circuit current at installation point Planned SCCR of the equipment or panel Inspector compares actual marked SCCR to the provided data If SCCR data is accurate then approval is give Inaccurate or incomplete data can result in “red-tag” and may require additional analysis Engineers and inspectors must work together

    25. Industrial Control Panel Marking Why are Marked SCCR’s Important? Needed to ensure compliance with NEC® and UL508A Helps to eliminate hazards where components and equipment could be applied above their ratings Simplifies inspection approval process for engineers and inspectors New installations Machinery relocation Contributes to a safe electrical system Guards against arc-flash hazards

    27. What is an Arc-Flash? A flow of current through the air between phase conductors or phase conductors and neutral or ground Usually unintentional Causes include: Human error Insulation failure Animal interference 5-10 times per day in U.S. - arc flash accidents injure or kill a worker

    28. Arc-Flash Hazard Standards OSHA Standards 29-CFR, Part 1910 – Work safety NFPA 70 (NEC) – Warning label requirements NFPA 70E 2004 – Appropriate work practices IEEE 1584 – 2002 – Arc flash hazard calculations

    29. Arc-Flash Hazard An arc flash hazard is defined in NFPA 70E as a dangerous condition associated with the release of energy caused by an electric arc The NEC requires a label that states the existence of an arc flash hazard OSHA regulations state the employers shall protect employees from recognized hazards NFPA 70E tells employers how to protect employees from recognized hazards IEEE 1584 shows the math to calculate the hazards

    30. Arc-Flash Panel Marking

    31. Arc-Flash Panel Marking

    32. Arc-Flash Hazard Arc Flash Hazard boundaries are based on voltage, available short-circuit current and predicted fault duration Different levels mean different protective gear required when servicing a panel ( i.e opening the panel door) This applies to all personnel that may need to access the panel or be exposed to live equipment May need an Arc Flash analysis performed Determine arc flash protection boundaries Personnel Protection Equipment (PPE) and training is a must

    33. What Does OHSA Say? OSHA regulations state in 1910.333 (a) that workers should not work on or near exposed live equipment (greater than 50 volts) except for one of two reasons: De-energizing introduces additional or increased hazards such as cutting ventilation to a hazardous location. Infeasible due to equipment design or operational limitations such as when voltage testing is required for diagnostics. When it is necessary to work on energized equipment you should follow safe work practices including assessing the risks, wearing proper PPE, and using the proper tools

    34. Personnel Protection Equipment - PPE PPE is designed to minimize injuries NFPA 70E requires any body part that is within the flash protection boundary be protected by using appropriate PPE (OSHA say basically the same thing) Hard hat Safety glasses or goggles (Arc-rated face shield) Hearing protection Gloves (leather, rubber) Flash suit (multi-layer clothes) Leather work shoes

    35. Personnel Protection Equipment - PPE

    36. PPE Protection From Arc-Flash!

    37. How to Avoid Arc-Flash Hazards Build control panels within the properly rated enclosures Minimize exposure to energized equipment Follow proper lockout/ tag-out procedures Design into control cabinets access options that will allow programming, data acquisition and system adjustment without having to open the panel door Maintain and update equipment and documentation Conduct safety training for all personnel

    38. Industrial Control Panel Access Options Properly applied they can reduce arc-flash hazards Save time and money - No PPE required Maintains enclosure type ratings Many options available: RJ 45, SUB-D9, USB, etc. Eternal shelves Document enclosures Operator panels Viewing windows

    39. Updated Industrial Control Panel

    41. NEC Article 409 & UL508A “Industrial Control Panels” Troy Miesse/ IE Business Development

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