1 Scope

NOTE This Standard covers enclosed combination and manual motor starters that control and protect a single motor served by an individual branch circuit outside a motor control center. (1.1)

NOTE A combination starter assembles a disconnecting means, branch-circuit short-circuit and ground-fault protection, a contactor, and a motor-overload relay into one listed enclosure. A manual motor protector (MMP) provides the disconnect and short-circuit protection with manual overload reset but no contactor, suiting motors that need no remote start/stop. (1.2)

1.3 The Contractor shall furnish and install enclosed motor starters complete with disconnecting means, overcurrent protection, contactor, overload relay, control power, enclosure, and accessories as specified and as scheduled.

1.4 Each starter shall control one motor on one branch circuit unless the Contract Documents specifically indicate a grouped or multi-motor installation.

NOTE Grouped motor installations, lineups on a common bus, and centralized motor control belong to Motor Control CentersMotor Control CentersResolves to the current edition.sync/motor-control-centers and are not furnished under this Standard. (1.5)

NOTE Variable-frequency drive packages with integral bypass and disconnect are specified under Low Voltage Variable Frequency DrivesLow-Voltage Variable Frequency DrivesResolves to the current edition.sync/low-voltage-variable-frequency-drives and are excluded here. (1.6)

NOTE Disconnect switches furnished without an overload relay or contactor assembly are specified under Enclosed Switches And DisconnectsEnclosed Switches and DisconnectsResolves to the current edition.sync/enclosed-switches-and-disconnects and are excluded here. (1.7)

NOTE Medium-voltage starters above 600 V, electronic soft starters, and starters factory-wired inside packaged equipment are outside the scope of this Standard. (1.8)

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited or a different edition is enforced by the Authority Having Jurisdiction.

2.2 Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

Standard	Title
NFPA 70 (NEC) Article 430	Motors, Motor Circuits, and Controllers
NFPA 70 (NEC) Article 430 Part IV	Motor Branch-Circuit Short-Circuit and Ground-Fault Protection
NFPA 70E	Standard for Electrical Safety in the Workplace
UL 508	Industrial Control Equipment
UL 508A	Industrial Control Panels
UL 60947-4-1	Low-Voltage Switchgear and Controlgear — Contactors and Motor-Starters
IEC 60947-4-1 (Ed. 5, 2023)	Low-Voltage Switchgear and Controlgear, Part 4-1: Contactors and Motor-Starters — Electromechanical Contactors and Motor-Starters
NEMA ICS 1	General Standards for Industrial Control and Systems
NEMA ICS 2	Controllers, Contactors and Overload Relays Rated Not More Than 2000 V AC or 750 V DC
NEMA ICS 6	Enclosures for Industrial Controls and Systems

NOTE UL 60947-4-1 is the harmonized UL/IEC listing path for IEC-frame contactors and motor starters and is the preferred listing for IEC-style devices sold in North America, effectively superseding the legacy UL 508 listing for those devices. (2.3)

NOTE NEMA ICS 2 is the governing sizing document for NEMA-frame starters and defines the horsepower-versus-voltage size table; it operates alongside, and does not conflict with, the UL listings. (2.4)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following action submittals for review before fabrication or ordering:

Product data for each starter type, including enclosure type, NEMA or IEC frame designation, voltage rating, and short-circuit current rating (SCCR).
Catalog cut sheets for the disconnecting means, overcurrent protective device, contactor, and overload relay, with the listed combination identified.
A motor-starter schedule correlating each starter to its motor tag, horsepower, nameplate full-load amperes (FLA), service factor, and branch circuit.
Overload relay selection data showing trip class and the proposed setting derived from motor nameplate FLA.
Shop drawings showing enclosure dimensions, gland/conduit entry locations, nameplate engraving, and accessory arrangement.
Control wiring (elementary/ladder) diagrams showing control power source, HOA logic, interlocks, and auxiliary contact connections to the building automation system (BAS) or PLC.

Action Submittalscheckbox

☑ Product data per starter type

☑ Component cut sheets (disconnect, OCPD, contactor, overload)

☑ Motor-starter schedule with nameplate FLA

☑ Overload relay trip class and setting data

☐ Enclosure shop drawings and nameplate engraving

☑ Control wiring (ladder) diagrams

3.1.2 The Contractor shall submit an SCCR substantiation for each combination assembly demonstrating that the listed assembly SCCR equals or exceeds the available fault current at the starter line terminals.

3.1.3 The SCCR substantiation shall reference a UL 508A series-rated combination or a tested assembly rating.

3.1.4 The SCCR substantiation shall not rely on the arithmetic sum of individual component SCCRs.

3.2 Closeout Submittals

3.2.1 The Contractor shall submit the following closeout submittals before Substantial Completion:

Operation and maintenance manuals covering overload reset, trip-class adjustment, and contactor maintenance.
Record (as-built) control diagrams reflecting field modifications.
Field test reports for insulation resistance and overload trip-current verification.
Arc-flash and equipment labels installed, with the source short-circuit study referenced.

Closeout Submittalscheckbox

☑ O&M manuals

☑ Record control diagrams

☑ Insulation resistance test reports

☑ Overload trip-current verification reports

☑ Arc-flash / equipment label confirmation

3.3 Informational Submittals

3.3.1 The Contractor shall submit the following informational submittals:

Manufacturer's installation instructions and recommended torque values.
Certification that each combination assembly is listed and labeled to UL 508 or UL 508A as applicable.
IEC coordination type (Type 1 or Type 2) declaration for IEC-frame assemblies.

Informational Submittalscheckbox

☑ Installation instructions and torque data

☑ UL 508 / UL 508A listing certification

☐ IEC coordination type declaration

4 Quality Assurance

4.1 Each combination motor controller assembly shall be listed and labeled to UL 508A as a factory-assembled industrial control panel, or shall be a field-assembled combination of individually listed UL 508 / UL 60947-4-1 components forming a listed combination.

4.2 Each contactor and overload relay shall be listed to UL 508 or UL 60947-4-1 as applicable to its frame type.

4.3 The manufacturer shall be a producer regularly engaged in the manufacture of motor control equipment of the type specified for a minimum of five years.

4.4 The installing Contractor shall employ electricians licensed in the jurisdiction of the Work and experienced in the installation of motor control equipment.

NOTE Mixing components from different manufacturers within one combination assembly is prohibited unless the resulting assembly carries a tested or calculated UL 508A series-combination SCCR rating that covers every component. (4.5)

4.6 One frame standard — NEMA or IEC — shall be designated for the entire project and held consistently across all starters to limit the spare-parts inventory and simplify maintenance.

Project Frame Standardradio

● NEMA frame (robust industrial / outdoor duty)

○ IEC frame (space-constrained / process panel)

NOTE The project frame standard shall be stated in the project electrical general requirements; ad-hoc mixing of NEMA and IEC frames across a project creates long-term maintenance and stocking problems. (4.7)

5 Environmental and Service Conditions

5.1 Starters shall be rated for continuous operation in the ambient and exposure conditions at their installed location without derating below the connected motor load.

NOTE Standard starters are rated for a maximum ambient of 40°C; locations in direct sun, in unconditioned mechanical rooms, or otherwise exceeding 40°C (104°F) require a 50°C-rated device or an enclosure derate. (5.2)

5.2.1 Where the installed ambient exceeds 40°C, the Contractor shall furnish starters rated for 50°C ambient or shall apply the manufacturer's published derating.

5.3 Enclosure type shall be selected for the environment of the installed location in accordance with NEMA ICS 6.

NOTE NEMA 3R is raintight but is not corrosion-resistant; coastal salt air, chemical wash-down, and wastewater service require a NEMA 4X 316 stainless steel or fiberglass enclosure rather than NEMA 3R. (5.4)

5.4.1 Outdoor starters in corrosive, coastal, or wash-down environments shall be furnished in NEMA 4X enclosures of an explicitly specified corrosion-resistant material.

Enclosure Typeradio

● NEMA 1 (indoor, conditioned, dry)

○ NEMA 12 (indoor industrial, dust/drip-tight)

○ NEMA 3R (outdoor, raintight)

○ NEMA 4 (indoor/outdoor watertight)

○ NEMA 4X (corrosion-resistant, watertight)

NEMA 4X Enclosure Materialselect

Not applicable (other enclosure type)

304 stainless steel

316 stainless steel

Fiberglass (non-metallic)

Maximum Ambient Temperature Ratingradio

● 40°C (standard)

○ 50°C (elevated ambient / direct sun)

6 Starter Type and Configuration

6.1 The starter type shall match the control function required by the driven load, the available fault current, and the project frame standard.

Control Configurationradio

● Full-voltage non-reversing (FVNR)

○ Full-voltage reversing (FVR)

○ Manual motor protector (MMP) only

Combination Type (Branch-Circuit Protective Device)radio

○ Fusible switch + fuses

● Thermal-magnetic circuit breaker

○ Motor circuit protector (MCP, instantaneous-only)

NOTE A full-voltage non-reversing (FVNR) starter is the default configuration; full-voltage reversing (FVR) is furnished only where the driven load requires both directions of rotation. (6.2)

NOTE Combination starters are classified by their branch-circuit protective device: fusible-switch type (switch plus fuses), circuit-breaker type (thermal-magnetic breaker), and motor-circuit-protector (MCP) type (instantaneous-only breaker). (6.3)

NOTE The MCP type uses an instantaneous-only breaker and achieves the highest available SCCR — up to 100 kA at 480 V — making it the preferred type where available fault current is high. (6.4)

NOTE A manual motor protector (MMP) provides the disconnecting means and short-circuit protection with a manual-reset thermal-magnetic trip and no contactor, and is appropriate only for motors that require no remote start/stop. (6.5)

6.6 Reversing Starters

6.6.1 Reversing starters shall consist of two contactors with both a mechanical interlock and an electrical interlock to prevent simultaneous closure.

6.6.2 Reversing contactors shall have a mechanical interlock in addition to any electrical interlock, in accordance with NEC 430.84.

NOTE An electrical interlock alone is insufficient because a welded or mis-wired contact could energize both contactors simultaneously and short the supply. (6.6.3)

6.6.4 Reversing starters shall be furnished factory-assembled with the mechanical interlock installed; field-added interlocks are not acceptable.

7 Ratings and Sizing

7.1 Voltage Rating

7.1.1 The starter and all components shall be rated for the nominal system voltage of the served branch circuit.

7.1.2 The control power transformer (CPT) and contactor coil voltages shall be confirmed against the system voltage and the control source before ordering; a mismatch is a common cause of field rework.

System Voltageradio

○ 200 V, 3Φ

○ 208 V, 3Φ

○ 240 V, 3Φ

● 480 V, 3Φ

○ 600 V, 3Φ

○ 240 V, 1Φ

7.2 NEMA Starter Size

7.2.1 NEMA-frame starters shall be sized by motor horsepower and supply voltage in accordance with the NEMA ICS 2 size table.

NEMA Starter Sizeselect

Size 00 (up to 1.5 HP / 480 V)

Size 0 (up to 5 HP / 480 V)

Size 1 (up to 10 HP / 480 V)

Size 2 (up to 25 HP / 480 V)

Size 3 (up to 50 HP / 480 V)

Size 4 (up to 100 HP / 480 V)

Size 5 (up to 200 HP / 480 V)

IEC frame (sized by motor FLA, not NEMA size)

NOTE NEMA sizes and their maximum three-phase horsepower at 480 V are: Size 00 = 1.5 HP, Size 0 = 5 HP, Size 1 = 10 HP, Size 2 = 25 HP, Size 3 = 50 HP, Size 4 = 100 HP, Size 5 = 200 HP, Size 6 = 400 HP, Size 7 = 600 HP, and Size 8 = 900 HP. (7.2.2)

NOTE Size 1 (10 HP / 480 V) and Size 2 (25 HP / 480 V) cover the majority of commercial and light-industrial starters, with Size 1 the single most common item. (7.2.3)

NOTE IEC-frame controllers shall be selected by motor full-load current and utilization category (AC-3 for standard motor duty) rather than by NEMA size. (7.2.4)

7.3 Short-Circuit Current Rating (SCCR)

7.3.1 The listed SCCR of each combination assembly shall equal or exceed the available fault current at the starter line terminals as determined by the project short-circuit study.

NOTE A NEMA Size 1 fusible starter may carry an SCCR as low as 10 kA while the upstream panelboard delivers 42 kA or more; specifying a size without verifying SCCR against the available fault current is a frequent and serious error. (7.3.2)

7.3.3 The minimum specified SCCR shall be 42 kA RMS symmetrical at 480 V for general commercial and industrial applications; 65 kA or 100 kA shall be specified where the short-circuit study shows higher available fault current.

Minimum Short-Circuit Current Rating (SCCR) at 480 Vradio

● 42 kA RMS sym (commercial/industrial baseline)

○ 65 kA RMS sym

○ 100 kA RMS sym (high available fault current)

NOTE Component SCCRs do not add; the assembly SCCR shall be established by a tested rating or a UL 508A series-combination calculation, never by summing individual device ratings. (7.3.4)

7.3.5 The available fault current at the starter line terminals shall be coordinated with the upstream distribution and the service, and verified against the Electrical Service EntranceElectrical Service EntranceResolves to the current edition.sync/electrical-service-entrance short-circuit study.

8 Overcurrent and Overload Protection

8.1 Branch-Circuit Short-Circuit and Ground-Fault Protection

8.1.1 The branch-circuit overcurrent protective device shall be sized within the maximum percentages of motor full-load current established by NEC Table 430.52 for the device type used.

NOTE Per NEC Table 430.52, the maximum settings are: inverse-time (thermal-magnetic) breaker at 250% of motor FLC, instantaneous-trip (MCP) breaker at 800% (up to 1300% where required by NEC 430.52(C)(1) Exception), dual-element time-delay fuse at 175%, and non-time-delay fuse at 300%. (8.1.2)

NOTE High-efficiency motors frequently carry locked-rotor code letter G or H with elevated inrush, which can require the MCP or fuse to be set toward the upper end of the NEC 430.52 range; the locked-rotor code letter shall be coordinated with the mechanical engineer. (8.1.3)

8.1.4 Branch-circuit conductors shall be sized at not less than 125% of the motor full-load current in accordance with NEC 430.22.

Branch-Circuit Protective Device Typeradio

● Inverse-time (thermal-magnetic) circuit breaker

○ Instantaneous-trip (MCP) circuit breaker

○ Dual-element time-delay fuse

○ Non-time-delay fuse

8.2 Overload Relay

8.2.1 A motor-overload relay shall be provided for running overload protection in accordance with NEC 430.32.

8.2.2 The overload relay shall have one pole per ungrounded conductor; three-phase motors shall be protected by a three-pole overload relay.

NOTE The overload relay shall be set from the motor nameplate full-load amperes (FLA) per NEC 430.6(A)(2), not from the NEC table FLC value; using the table value is one of the most common inspection failures. (8.2.3)

8.2.4 For motors with a service factor of 1.15 or greater or a marked temperature rise of 40°C or less, the overload relay shall be set at 115% of nameplate FLA per NEC 430.32.

8.2.5 For all other motors, the overload relay shall be set at 125% of nameplate FLA per NEC 430.32.

NOTE Electronic (solid-state) overload relays are preferred for high-cycle duty and for Class 20/30 adjustability, and provide field-adjustable trip via a front-mounted dial. (8.2.6)

8.2.7 Electronic overload relays with integral phase-loss protection shall be provided for critical three-phase motors, because bimetallic relays do not detect single-phasing until the surviving phases overload.

Overload Relay Typeradio

● Electronic (solid-state), adjustable

○ Bimetallic thermal

○ Manual motor protector integral trip

8.2.8 The overload relay trip class shall be Class 20 for general-purpose motors, Class 10 for submersible pumps and motors with short thermal time constants, and Class 30 for high-inertia loads such as large fans and centrifuges.

8.2.9 Defaulting to Class 20 on a submersible pump motor (which needs Class 10) causes nuisance trips at startup, while Class 30 on a standard fan motor delays fault protection; the trip class shall be matched to the load.

Overload Relay Trip Classradio

○ Class 10 (submersible pumps, short thermal constant)

● Class 20 (standard / general-purpose)

○ Class 30 (high-inertia loads)

8.2.10 For IEC-frame combination controllers, the short-circuit coordination type shall be declared on the submittal.

8.2.11 Type 2 coordination (no damage to the contactor or overload relay after a short-circuit test) shall be specified for process and other critical applications.

8.2.12 Type 1 coordination shall be permitted only for non-critical duty.

IEC Coordination Typeradio

● Not applicable (NEMA frame)

○ Type 1 (some damage permissible, non-critical)

○ Type 2 (no damage, process/critical)

9 Disconnecting Means

9.1 Each combination starter shall include a disconnecting means rated for the motor in accordance with NEC 430.101 through 430.113.

9.2 The disconnecting means shall be capable of being locked in the open position with a provision that remains in place with or without the lock installed.

9.3 The enclosure door shall be mechanically interlocked with the disconnecting means so the door cannot be opened with the disconnect closed, except by a defeatable interlock for qualified persons.

NOTE A manual motor protector used as both disconnect and short-circuit protection shall satisfy the disconnecting-means requirements of NEC Article 430 for the motor it serves. (9.4)

10 Control Power and Accessories

10.1 Control Power

10.1.1 Control power shall be 120 V AC, 60 Hz derived from an integral control power transformer (CPT) unless an external control voltage is indicated.

Control Voltageradio

● 120 V AC via integral CPT

○ 24 V DC (external, BAS-supplied)

○ Line voltage (no control transformer)

10.1.2 The integral CPT shall be sized at not less than the inrush plus sealed VA of the connected control devices.

Control Power Transformer (CPT) VA Ratingselect

None (line-voltage or external control)

100 VA

250 VA

500 VA

750 VA

1000 VA

NOTE 500 VA is the typical default CPT size for a single starter with pilot devices. (10.1.3)

10.1.4 A control power transformer shall be furnished whenever control wiring extends beyond the equipment enclosure or a 120 V control circuit is required by the system integrator or BAS contractor.

NOTE Omitting the CPT from the initial pricing scope is a routine source of RFIs on projects with BAS or remote control requirements. (10.1.5)

10.1.6 The contactor coil voltage shall match the control power source.

10.1.7 A 24 V DC BAS output driving a 120 V AC coil without an interposing relay will damage the BAS output; this configuration shall not be applied.

NOTE Verify coil voltage compatibility before ordering; a coil voltage mismatch is a common source of equipment damage that is difficult to remedy in the field. (10.1.8)

10.2 Accessories

10.2.1 Door-mounted and internal accessories shall be furnished as scheduled and shall be factory-installed and pre-wired to a terminal block where they interface with field wiring.

10.2.2 A Hand-Off-Auto (HOA) selector switch shall be furnished where the motor is controlled by both a local hand position and an automatic (BAS/PLC) signal.

10.2.3 Auxiliary contacts for run status and fault status shall be furnished and wired to a terminal block for connection to the building automation system or PLC where remote monitoring is indicated.

Door-Mounted and Internal Accessoriescheckbox

☑ Hand-Off-Auto (HOA) selector switch

☑ Run pilot light

☐ Fault/trip pilot light

☑ Auxiliary contacts (status to BAS/PLC)

☑ Control circuit fuse

☐ Shunt trip

☐ Under-voltage release

☐ Phase-failure / phase-unbalance relay

10.2.4 A phase-failure or phase-unbalance relay shall be specified for three-phase motors serving critical loads where the overload relay does not provide integral phase-loss protection.

10.2.5 Pilot light type shall be specified in the motor-starter schedule.

Pilot Light Typeradio

● LED, push-to-test

○ LED, standard

○ Incandescent / transformer type

NOTE LED pilot lights are preferred over incandescent for longevity and lower heat dissipation inside the enclosure. (10.2.6)

11 Enclosure and Nameplates

11.1 Enclosures shall comply with NEMA ICS 6 for the specified type and shall protect the enclosed equipment against the environmental conditions at the installed location.

11.2 Each starter enclosure shall bear a permanent, engraved nameplate identifying the motor served, the equipment tag, the voltage, and the source panel and circuit.

NOTE Conduit and cable entries shall be located to preserve the enclosure rating; field-drilled entries on NEMA 4X enclosures shall use listed, rated fittings that maintain the enclosure type. (11.3)

NOTE Each starter shall bear an arc-flash warning label in accordance with NEC 110.16 and NFPA 70E, referencing the incident energy from the project short-circuit and arc-flash study. (11.4)

11.4.1 The Contractor shall install an arc-flash and equipment label on each starter consistent with the project arc-flash study before energization.

12 Testing

12.1 Factory Testing

12.1.1 Factory-assembled combination panels shall be tested per UL 508A, including dielectric (hi-pot) withstand, overload relay calibration, and control circuit continuity, prior to shipment.

12.2 Field Testing

12.2.1 The Contractor shall perform an insulation resistance (megger) test on each starter power circuit and record the results before energization.

12.2.2 The Contractor shall verify the overload relay trip-current setting against the motor nameplate FLA and record the as-set value.

12.2.3 The Contractor shall perform an operational test of each starter through all control positions, including HOA logic, interlocks, and status feedback to the BAS or PLC.

Field Tests Requiredcheckbox

☑ Insulation resistance (megger) of power circuit

☑ Overload trip-current setting verification

☑ Operational test through all control positions

☐ BAS/PLC status feedback verification

13 Installation

13.1 Starters shall be installed plumb, level, and securely mounted to a structural surface or rack at a height that places the operating handle within the reach limits of NEC 404.8 and 430.107.

13.2 Starters serving HVAC and plumbing equipment shall be coordinated with the equipment locations served, including water-source heat pump and packaged-unit motors where applicable.

13.3 Conductor terminations shall be torqued to the manufacturer's published values, and the torque shall be recorded.

13.4 Working clearances in front of and around each starter shall comply with NEC 110.26 and shall not be obstructed by piping, ductwork, or other equipment.

NOTE Where the starter serves a motor on a water-source heat pump or a packaged HVAC unit, coordinate the disconnect location and control interface per the equipment standard, such as Water Source Heat PumpsWater-Source Heat PumpsResolves to the current edition.sync/water-source-heat-pumps. (13.5)

13.6 Equipment grounding conductors shall be terminated to the enclosure ground bus or lug, and the enclosure shall be bonded in accordance with NEC Article 250.

14 Delivery, Storage, and Handling

14.1 Starters shall be delivered in the manufacturer's original packaging, clearly labeled with the equipment tag and destination.

14.2 Starters shall be stored indoors in a clean, dry, temperature-controlled space and protected from construction dust, moisture, and physical damage until installed.

14.3 Enclosures shall not be used as a support or work surface during construction, and openings shall remain sealed until conduit and cable are installed.

15 Warranty

15.1 The manufacturer shall warrant each starter against defects in materials and workmanship for a minimum of 18 months from shipment or 12 months from energization, whichever occurs first, unless a longer period is specified.

Warranty Periodradio

○ 12 months from energization

● 18 months from shipment

○ 24 months from energization

○ 36 months from energization

15.2 The Contractor shall warrant the installation, including terminations and field settings, for a minimum of one year from Substantial Completion.

16 Spare Parts

16.1 The Contractor shall furnish spare parts as scheduled, consistent with the project frame standard to avoid stocking incompatible NEMA and IEC components.

16.1.1 The Contractor shall furnish the following spare parts to the Owner at closeout:

One spare contactor coil for each contactor size used on the project.
One spare overload relay for each trip class and frame size used.
One spare set of control fuses for each fuse rating used.
One spare set of auxiliary contacts for each contactor size used.

Spare Parts to Ownercheckbox

☑ Spare contactor coil (per size)

☑ Spare overload relay (per class/frame)

☑ Spare control fuses (per rating)

☐ Spare auxiliary contact set (per size)

☐ Spare pilot light lamps/LEDs