Suggestion on How to Use Industry Trainers are

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Suggestion on How to Use • Industry Trainers are encouraged to use this material

Suggestion on How to Use • Industry Trainers are encouraged to use this material in their sessions • Download the presentation file • Print the Notes pages and read them as you view the presentation in the “Slide Show” view. In this way you see the slides in large format and have animation (when available) © 2015 Eaton. All Rights Reserved. . 1

SCCR for Industrial Control Panels © 2015 Eaton. All Rights Reserved. .

SCCR for Industrial Control Panels © 2015 Eaton. All Rights Reserved. .

Interrupting Rating (of Overcurrent Devices) • NEC® Article 100 Definition • Highest current an

Interrupting Rating (of Overcurrent Devices) • NEC® Article 100 Definition • Highest current an OVERCURRENT DEVICE (fuse or circuit breaker) is rated to safely interrupt. • Self protection rating only • NEC® 110. 9 Interrupting Rating. • Requires the overcurrent device to have an interrupting rating not less than the maximum available short-circuit current. • The maximum short-circuit current must be calculated and varies, based on system size/location. • Similar Requirements in OSHA 1910. 303(b)(4) © 2015 Eaton. All Rights Reserved. . 3

Short-Circuit Current Ratings (of Equipment) • NEC® Article 100 Definition • The highest current

Short-Circuit Current Ratings (of Equipment) • NEC® Article 100 Definition • The highest current EQUIPMENT can withstand without extensive damage (fire or shock hazard). • Combination of equipment/component and overcurrent device • May be based on a specific type of overcurrent device • NEC® 110. 10 Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics. • Requires the equipment to have a short circuit current rating not less than the maximum available short-circuit current. • The maximum short-circuit current must be calculated and varies based on system size/location. • Similar Requirements in OSHA 1910. 303(b)(5) © 2015 Eaton. All Rights Reserved. . 4

SCCR Marking Requirements • 430. 8 – Marked on motor controllers • 440. 4(B)

SCCR Marking Requirements • 430. 8 – Marked on motor controllers • 440. 4(B) – Marked on HVAC equipment • 409. 110(4) – Marked on industrial control panels • 409. 22 – Short-circuit current cannot exceed marked SCCR • 670. 3(A)(4) – Marked on industrial machinery control panel • 670. 5 – Short-circuit current cannot exceed marked SCCR • Typically HVAC, ICPs and IM is rated only 5 k. A! © 2015 Eaton. All Rights Reserved. . 5

Short-circuit Current Marking Requirement • 110. 24 Available Fault Current. • (A) Service equipment

Short-circuit Current Marking Requirement • 110. 24 Available Fault Current. • (A) Service equipment in other than dwelling units must be marked with the maximum available fault current and date of calculation • (B) If short-circuit current increases due to system modification, the marking must be updated. © 2015 Eaton. All Rights Reserved. . 6

How to Comply? Engineer – Calculate All equipment must comply with: NEC 110. 9

How to Comply? Engineer – Calculate All equipment must comply with: NEC 110. 9 (IR) &110. 10 (SCCR) Isc = 60, 142 A Contractor – Label Max Avail. Fault Current = 58, 524 A Service Equipment Date Determined/Calculated: 9/2010 Required per NEC 110. 24 Isc = 38, 525 A HVAC SCCR = 40 k. A Isc = 42, 153 A Isc = 27, 532 A Industrial Machinery Panel Industrial Control Panel SCCR = 65 k. A SCCR = 30 k. A © 2015 Eaton. All Rights Reserved. . Isc = 18, 752 A Motor Controller SCCR = 25 k. A 7

What is Typical for Industrials? © 2015 Eaton. All Rights Reserved. . 8

What is Typical for Industrials? © 2015 Eaton. All Rights Reserved. . 8

How to Determine SCCR? • Short-Circuit Current Rating (SCCR) • Can be established by

How to Determine SCCR? • Short-Circuit Current Rating (SCCR) • Can be established by testing during the listing and labeling process OR • Can be determined using an approved (calculation) method • UL 508 A Supplement SB is an approved method (industrial control panels and industrial machinery control panel) • AHJ Approved Method • NRTL field evaluation can also be used. © 2015 Eaton. All Rights Reserved. . 9

Industrial Control Panel SCCR An industrial control panel is an assembly that consists of

Industrial Control Panel SCCR An industrial control panel is an assembly that consists of at least two components. They may be “power” components such as motor controllers, overload relays, fused disconnect switches, and circuit breakers, or they may be “control circuit” components such as push buttons, pilot lights, selector switches, timers, switches, and control relays, or they may be a combination of “power” and “control circuit” components. The controlled equipment is not considered to be a part of the industrial control panel. 10 © 2015 Eaton. All Rights Reserved. . 10

UL 508 A Supplement SB • What Needs to be Analyzed per UL 508

UL 508 A Supplement SB • What Needs to be Analyzed per UL 508 A, Supplement SB? • All power circuit components • Feeder and branch circuit components that supply power to loads (motors, lighting, heating and appliances) • Includes disconnect switches, fuses, circuit breakers, load controllers, overload relays, power distribution/terminal blocks, bus bars, etc. • The Exception for HVAC equipment rated 60 A or less deleted in 2017 NEC. • Control circuit components are NOT required to be analyzed • Pushbuttons, pilot lights, selector switches, timers, control relays, etc. © 2015 Eaton. All Rights Reserved. . 11

“ 2 Sweep” Method (Based on UL 508 A) • Sweep 1 – Component

“ 2 Sweep” Method (Based on UL 508 A) • Sweep 1 – Component Rating • Determine lowest power circuit component SCCR • Use current-limiting overcurrent protective devices or transformers in feeder circuit to increase low SCCRs downstream • Sweep 2 – Overcurrent Protective Device Rating • Determine lowest overcurrent device IR or combination motor controller SCCR • Lowest value of Sweep 1 and 2 = Assembly SCCR 12 © 2015 Eaton. All Rights Reserved. . 12

UL 508 A Supplement SB • What are the Rules (Sweep 1)? • Lowest

UL 508 A Supplement SB • What are the Rules (Sweep 1)? • Lowest component SCCR limits assembly SCCR unless: • Combination ratings can be used to increase branch circuit component ratings – check with component manufacturer © 2015 Eaton. All Rights Reserved. . 13

Combination Ratings - Feeder Component SCCR OCPD I. R. Nameplate Voltage: 480 SCCR: 100

Combination Ratings - Feeder Component SCCR OCPD I. R. Nameplate Voltage: 480 SCCR: 100 k. A 100 k. A • Use combination ratings with specified/marked OCPD to fix low rated feeder components • Note: PDB must have feeder circuit spacings (Listed vs. Recognized) Combination ratings of overcurrent protective devices and components can be used © 2015 Eaton. All Rights Reserved. . 14

Combination Ratings - PDBs PDB w/14 AWG Load Side Conductors SCCR=100 k. A w/175

Combination Ratings - PDBs PDB w/14 AWG Load Side Conductors SCCR=100 k. A w/175 A Class J fuse or smaller PDB w/12 AWG Load Side Conductors SCCR=200 k. A w/200 A Class J fuse or smaller 15 © 2015 Eaton. All Rights Reserved. . 15

Combination Ratings - Branch Component SCCR OCPD I. R. Nameplate Voltage: 480 SCCR: 100

Combination Ratings - Branch Component SCCR OCPD I. R. Nameplate Voltage: 480 SCCR: 100 k. A 100 k. A • Use combination ratings with specified/marked OCPD to fix low rated branch components Combination ratings of overcurrent protective devices and components can be used © 2015 Eaton. All Rights Reserved. . 16

Combination Ratings – Motor Starter & Contactor © 2015 Eaton. All Rights Reserved. .

Combination Ratings – Motor Starter & Contactor © 2015 Eaton. All Rights Reserved. . 17

High Fault Current Substitution with Current-Limiting Overcurrent Device SB 4. 2. 3 A high

High Fault Current Substitution with Current-Limiting Overcurrent Device SB 4. 2. 3 A high fault short circuit current rating for a motor controller, an overload relay, or a combination motor controller, as specified in SB 4. 2. 2 (a) or (c), shall only be used as the short circuit current rating of the component when the specified branch circuit protective device is provided. Exceptions: (1) CL Fuse with more CL Fuse (2) Provided in the field if marked (3) CL CB with more CL CB NEW Exception No. 4: When the specified branch circuit protection related to the high fault shortcircuit current rating is a non-current limiting overcurrent device, a current-limiting overcurrent device is able to be used at the same high fault rating where the interrupting rating of the currentlimiting overcurrent device is equal to or greater than the specified overcurrent device. Current limiting overcurrent devices can be used in lieu of a non-current limiting overcurrent device for protection of motor controllers and still maintain a high fault short circuit current rating. © 2015 Eaton. All Rights Reserved. . 18

Use of CL Devices - OCPD • CL Device must be in the feeder

Use of CL Devices - OCPD • CL Device must be in the feeder circuit • For CL Fuses or Circuit Breakers • Use PEAK Let-through, Not RMS Let-Through (more conservative). Compare peak let-through with component SCCR • Fuses - cannot use manufacturer specific fuse data – only tables (or formulas) based on performance requirements from UL 248 (conservative - applies to all manufacturers) • Circuit Breakers - must be Listed and marked “currentlimiting” and use published peak let-thru curves • Can only raise downstream branch circuit component SCCR (not fuse IR, not CB IR, not fuse/CB series rating, not CB/CB series rating, not combination motor controller SCCR) • New - can be provided in the field (outside of panel) if properly marked on industrial control panel. © 2015 Eaton. All Rights Reserved. . 19

Feeder vs. Branch Circuits Feeder Circuit Branch Circuit © 2015 Eaton. All Rights Reserved.

Feeder vs. Branch Circuits Feeder Circuit Branch Circuit © 2015 Eaton. All Rights Reserved. . 20

Use of CL Devices - OCPD Component SCCR Nameplate Voltage: 480 SCCR: 15 k.

Use of CL Devices - OCPD Component SCCR Nameplate Voltage: 480 SCCR: 15 k. A 18 k. A OCPD I. R. FC LT 50 k. A 12 k. A 100 k. A 14 k. A 200 k. A 20 k. A F • Current limiting feeder OCPD can be used to increase branch component SCCR. • If Component SCCR is less than let-through current at a given short-circuit current, raise component SCCR to that shortcircuit current value. B Use of CL OCPD can only fix components © 2015 Eaton. All Rights Reserved. . 21

Current-Limiting Feeder Protective Devices Installed in the Field NEW: SB 4. 3. 4 The

Current-Limiting Feeder Protective Devices Installed in the Field NEW: SB 4. 3. 4 The specified circuit breaker marked "current limiting" or current-limiting Class of fuse supplied in the feeder circuit that limits the peak let-through current available in accordance with SB 4. 3. 2 and SB 4. 3. 3 is able to be provided in the field when the panel is marked in accordance with SB 5. 1. 3 An industrial control panel marked with a high fault short circuit current rating and is not provided with the required feeder circuit protective device as specified in the SB 4. 3. 4 shall be marked with the type and size of feeder circuit protection required to be installed in the field. This marking shall be included as part of the marking in SB 5. 1. 1. • Allows the use of the let-through to increase branch component SCCR even if the current-limiting overcurrent device is supplied in the field, provided the associated required marking is provided including the SCCR marking. © 2015 Eaton. All Rights Reserved. . 22

Use of CL Devices - Transformers • CL Transformer must be in feeder •

Use of CL Devices - Transformers • CL Transformer must be in feeder • Previously only 5 or 10 KVA Transformers • Now Use Equations or Tables © 2015 Eaton. All Rights Reserved. . 23

Use of CL Devices - Transformers Component SCCR OCPD I. R. Nameplate Voltage: 480

Use of CL Devices - Transformers Component SCCR OCPD I. R. Nameplate Voltage: 480 SCCR: 200 k. A 10 k. VA • 480 -120 V, single phase, 2. 1 impedance or more • Max short-circuit from table 3970 A • If OCPD IR/Components SCCR is higher, then assign entire circuit I. R. of primary overcurrent device Use of transformers can increase secondary component/OCPD ratings © 2015 Eaton. All Rights Reserved. . 24

UL 508 A Supplement SB • Reviewing the Rules for Sweep 2 • Lowest

UL 508 A Supplement SB • Reviewing the Rules for Sweep 2 • Lowest overcurrent protective device interrupting rating (or SCCR for some devices) always limits assembly SCCR • All Feeder and branch circuit overcurrent devices • Tested series combination ratings or series ratings (fusecircuit breaker or circuit breaker-circuit breaker) are NOT allowed. • Branch circuit overcurrent devices, connected to the feeder circuit, supplying a control circuit. • Supplemental protective devices, protecting the control circuit transformer, in a motor branch circuit. © 2015 Eaton. All Rights Reserved. . 25

Why High SCCR? • NEC & Equipment standards require the SCCR to be marked

Why High SCCR? • NEC & Equipment standards require the SCCR to be marked • NEC requires the marked value to be adequate for the maximum available short-circuit current • High SCCR is often preferred • Flexibility of application • Multiple installations • Short-circuit current unknown • Insufficient SCCR can delay installation © 2015 Eaton. All Rights Reserved. . 26

Fix It - Solutions • High I. R. Protective Devices • Class R •

Fix It - Solutions • High I. R. Protective Devices • Class R • Class J Drive Fuse • Class T • Class CC • Cube. Fuse • High Speed • High IR/CL CBs © 2015 Eaton. All Rights Reserved. . 27

Fix It - Solutions • High SCCR Components © 2015 Eaton. All Rights Reserved.

Fix It - Solutions • High SCCR Components © 2015 Eaton. All Rights Reserved. . 28

© 2015 Eaton. All Rights Reserved. . 29

© 2015 Eaton. All Rights Reserved. . 29