NEC Article 409 UL 508 A Industrial Control

NEC Article 409 & UL 508 A “Industrial Control Panels” Troy Miesse/ IE Business Development Industrial Control Panels Miesse/ IE / 3 -1 -07 1

Industrial Control Panels Miesse/ IE / 3 -1 -07 2

Agenda • NFPA 70: National Electric Code (NEC®) • Short Circuit Current Ratings • Article 409 “Industrial Control Panels” • UL 508 A (Supplement SB) • Arc Flash and NFPA 70 E • Personnel Protection Equipment Industrial Control Panels Miesse/ IE / 3 -1 -07 3

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 Industrial Control Panels Miesse/ IE / 3 -1 -07 4

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 k. A at the system voltage. Example: 18 k. A 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). Industrial Control Panels Miesse/ IE / 3 -1 -07 5

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. Industrial Control Panels Miesse/ IE / 3 -1 -07 6

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 Industrial Control Panels Miesse/ IE / 3 -1 -07 7

2005 NEC • The 2005 NEC requires SCCR markings on all: • Industrial Control Panels -NEC Article 409 • Motor controllers -NEC Article 430. 8 • HVAC controllers -NEC Article 440. 4(B) • Industrial machinery -NEC Article 670. 3 • Meter disconnects -NEC Article 230. 82(3) Industrial Control Panels Miesse/ IE / 3 -1 -07 8

How do I Determine the Panel SCCR ? NEC Article 409. 110 states that the SCCR of an industrial control panel is based on one of the following: • SCCR of a Listed and labeled assembly • SCCR based on the use of an “approved” method • UL 508 A Supplement SB is given as an example of an approved method • Method approved by local electrical inspector (AHJ) • Engineer (PE) approved apparent RMS method. Industrial Control Panels Miesse/ IE / 3 -1 -07 9

How do I Determine the Panel SCCR ? NEC Article 409. 110 states that the SCCR of an industrial control panel is based on one of the following: • SCCR of a Listed and labeled assembly • Easy enough if you just buying the control panel • Not an option if you are building or specifying a control panel Industrial Control Panels Miesse/ IE / 3 -1 -07 10

How do I Determine the Panel SCCR ? NEC Article 409. 110 states that the SCCR of an industrial control panel is based on one of the following: • SCCR of a Listed and labeled assembly • SCCR based on the use of an “approved” method • UL 508 A Supplement SB is given as an example of an approved method Industrial Control Panels Miesse/ IE / 3 -1 -07 11

UL 508 A Standard • UL 508 A 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 Industrial Control Panels Miesse/ IE / 3 -1 -07 12

UL 508 A Supplement SB describes three steps to determine the SCCR of industrial control panels: 1) Determine the SCCR of all individual power components by one of the following methods: - SCCR rating marked on the component - Use assumed SCCRs in table SB 4. 1 of Supplement SB - Use the tested SCCR from component combinations per UL 508 2) Modify the SCCR of certain series combinations if current -limiting devices are used in the feeder circuit. 3) Determine the overall panel SCCR according to charts in SB 4. 4 - Flow chart that help understanding and assignment of SCCR Industrial Control Panels Miesse/ IE / 3 -1 -07 13

UL 508 A Standard – Supplement SB Industrial Control Panels Miesse/ IE / 3 -1 -07 14

UL 508 A Supplement SB – (review) UL 508 A Supplement SB describes three steps to determine the SCCR of industrial control panels: 1) Determine the SCCR of all individual power components by one of the following methods: - SCCR rating marked on the component - Use assumed SCCRs in table SB 4. 1 of Supplement SB - Use the tested SCCR from component combinations per UL 508 2) Modify the SCCR of certain series combinations if current -limiting devices are used in the feeder circuit. 3) Determine the overall panel SCCR according to charts in SB 4. 4 - Flow chart that help understanding and assignment of SCCR Industrial Control Panels Miesse/ IE / 3 -1 -07 15

UL 508 A Supplement SB 4. 4 Chart Industrial Control Panels Miesse/ IE / 3 -1 -07 16

SCCR Calculation Example – Individual SCCR’s Control Trans W/ fuses Control Relay Terminal Blocks Main CB Power Circuit SCCR at 480 V § Main CB 30 k. A § Contactor 5 k. A § Overload Relay 5 k. A § Fuses on C-Trans 200 k. A Control Circuit § Control Trans § Control Relay § Terminal Blocks ------- Contactor W/ Overload Industrial Control Panels Miesse/ IE / 3 -1 -07 17

SCCR Calculation Example – Individual SCCR’s Control Trans W/ fuses Control Relay Terminal Blocks Main CB Power Circuit SCCR at 480 V § Main CB 30 k. A § Contactor 5 k. A § Overload Relay 5 k. A § Fuses on C-Trans 200 k. A If no additional information is available the Industrial Control Panel must be rated at the lowest rating of any component: 5 k. A Contactor W/ Overload Industrial Control Panels Miesse/ IE / 3 -1 -07 18

SCCR Calculation Example – Tested Combinations Control Trans W/ fuses Control Relay Terminal Blocks Main CB Power Circuit SCCR at 480 V § Main CB 30 k. A § Contactor 5 k. A § Overload Relay 5 k. A § Fuses on C-Trans 200 k. A Control Circuit § Control Trans § Control Relay § Terminal Blocks ------- Contactor W/ Overload Industrial Control Panels Miesse/ IE / 3 -1 -07 19

SCCR Calculation Example – Tested Combinations Control Trans W/ fuses Control Relay Terminal Blocks Main CB Power Circuit SCCR at 480 V § Main CB § Contactor 30 k. A § Overload Relay § Fuses on C-Trans 200 k. A UL 508 component combination test results show that the CB and starter combination can be rated at 30 k. A. The Industrial Control Panel can now be rated at a higher SCCR: 30 k. A Contactor W/ Overload Industrial Control Panels Miesse/ IE / 3 -1 -07 20

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 508 A Articles SB 3. 2 and SB 4. 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. Industrial Control Panels Miesse/ IE / 3 -1 -07 21

Industrial Control Panel Marking Per NEC an industrial control panel shall be marked with the following information that is plainly visible after installation: • Manufacturer’s name, trademark, etc. • Supply voltage, phase, frequency and full-load current • SCCR • Identify as service equipment (if applicable) • Electrical wiring diagram or the index number • Enclosure type (rating) number Industrial Control Panels Miesse/ IE / 3 -1 -07 22

Panel Marking Paper Converting Machine Serial Number Current Largest Motor H. P. Max OCP Device Voltage Phase & Freq. . Short Circuit Current Rating Diagram Number RC 2356 YUP 77 125 Amperes 20 Horsepower 60 Ampere 460 - 480 volts 3 ph. , 60 Hz 100, 000 Amperes RMS RT-1982 Ri-Machine Goodold, USA Industrial Control Panels Miesse/ IE / 3 -1 -07 23

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 Industrial Control Panels Miesse/ IE / 3 -1 -07 24

Industrial Control Panel Marking Why are Marked SCCR’s Important? • Needed to ensure compliance with NEC® and UL 508 A • 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 Industrial Control Panels Miesse/ IE / 3 -1 -07 25

What is Arc Flash? Industrial Control Panels Miesse/ IE / 3 -1 -07 26

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 Industrial Control Panels Miesse/ IE / 3 -1 -07 27

Arc-Flash Hazard Standards • • OSHA Standards 29 -CFR, Part 1910 – Work safety NFPA 70 (NEC) – Warning label requirements NFPA 70 E 2004 – Appropriate work practices IEEE 1584 – 2002 – Arc flash hazard calculations Industrial Control Panels Miesse/ IE / 3 -1 -07 28

Arc-Flash Hazard • An arc flash hazard is defined in NFPA 70 E 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 70 E tells employers how to protect employees from recognized hazards • IEEE 1584 shows the math to calculate the hazards Industrial Control Panels Miesse/ IE / 3 -1 -07 29

Arc-Flash Panel Marking Flash Protection Boundary: 2. 9 ft • Boundary where person could receive 2 nd degree burns from arc flash - 1. 2 cal/cm 2 Incident Energy: 2. 3 Cal/ cm 2 • Amount of energy produced during an arc flash Working Distance: 18 in. • The distance between worker and arc source Required PPE Level: 1 • Protective clothing and apparatus to protect against arc flash injury Industrial Control Panels Miesse/ IE / 3 -1 -07 30

Arc-Flash Panel Marking Shock Hazard Voltage: 3450 VAC • Potential voltage levels that can be delivered Limited Approach: 10. 0 ft. • Shock protection boundary – Qualified personnel only unless escorted Restricted Approach: 2. 2 ft. • Shock protection boundary – Qualified personnel only with PPE Prohibited Approach: 0. 6 ft. • Shock protection boundary – Qualified personnel only with PPE (contact is possible) Industrial Control Panels Miesse/ IE / 3 -1 -07 31

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 Industrial Control Panels Miesse/ IE / 3 -1 -07 32

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: 1. De-energizing introduces additional or increased hazards such as cutting ventilation to a hazardous location. 2. 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 Industrial Control Panels Miesse/ IE / 3 -1 -07 33

Personnel Protection Equipment - PPE • PPE is designed to minimize injuries • NFPA 70 E 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 Industrial Control Panels Miesse/ IE / 3 -1 -07 34

Personnel Protection Equipment - PPE Notes: Ø 1 cal/ cm 2 equates to holding ones finger over the tip of a flame of a cigarette lighter for 1 sec. Ø 1. 2 cal/ cm 2 is considered the threshold for a curable burn (second-degree) Industrial Control Panels Miesse/ IE / 3 -1 -07 35

PPE Protection From Arc-Flash! Industrial Control Panels Miesse/ IE / 3 -1 -07 36

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 Industrial Control Panels Miesse/ IE / 3 -1 -07 37

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-D 9, USB, etc. Eternal shelves Document enclosures Operator panels Viewing windows Industrial Control Panels Miesse/ IE / 3 -1 -07 38

Updated Industrial Control Panel Paper Converting Machine 7 A 345 RTT-04 480 V, 3 -phase, 60 Hz, FLC 60 A SCCR 18 k. A Diagram-RTT-06 Ri. Machine – Spfld, OH Industrial Control Panels Miesse/ IE / 3 -1 -07 39

Industrial Control Panels Miesse/ IE / 3 -1 -07 40

NEC Article 409 & UL 508 A “Industrial Control Panels” Troy Miesse/ IE Business Development Industrial Control Panels Miesse/ IE / 3 -1 -07 41