Make Knockouts and Install Cable Connectors

A. Finished-Project Specification

Quantity: one metal box or training enclosure with each intended knockout removed at the correct size, fitted with a connector listed for the exact cable, raceway, conductor material, size range, and enclosure condition, tightened by the approved method, with cable sheath protected through the connector, cable secured at the required support point outside the box, and all unused openings closed with listed closures.

B. Component Schedule

Component	Quantity	Material	Finished Size	Preparation
Metal enclosure	1	Listed metal box or training enclosure	Per approved plan	Verified disconnected from all power sources
Knockout opening	1 per cable entry	Manufactured scored knockout in enclosure wall	Matched to listed connector size	Removed cleanly and deburred
Cable connector	1 per cable entry	Listed for cable type, conductor material, and enclosure condition	Matched to knockout and cable diameter	Disassembled per manufacturer instructions before insertion
Locknut or bushing	1 per connector (or as supplied)	Connector manufacturer's listed component	Matched to connector body	Tightened by approved method
Closure plug	1 per unused opening	Listed for the enclosure knockout size	Matched to unused knockout size	Seated and secured
Cable support (staple or clamp)	As required by cable count and route	Listed for the cable type	Matched to cable diameter	Installed outside the box at the required distance

C. Material Takeoff

• Enclosure: one metal box or training enclosure with concentric or single-size knockouts sized for the planned connectors.
• Connectors: one listed cable connector per planned cable entry, sized and typed to the cable and enclosure condition.
• Closures: one listed closure plug per unused knockout opening.
• Cable support hardware: listed staples or cable clamps sufficient for the required support point at each cable entry.
• Cable or raceway samples: lengths of NM cable or raceway sufficient to demonstrate preparation and insertion at each connector.

D. Reference Conventions

Use the reference terms defined in the Reference Conventions table above: scored knockout, concentric ring, listed connector, locknut or bushing, cable support point, and closure plug. Do not remove a knockout or install a connector without first confirming these terms against the specific enclosure and connector in hand.

E. Acceptance Standards

Check	Standard
Knockout removal	Correct size removed cleanly, without tearing past the scored line or enlarging the opening
Deburring	Opening free of sharp edges without enlargement or deformation
Connector selection	Listed for the exact cable, raceway, conductor material, size range, and enclosure condition
Connector seating	Locknut, bushing, or threaded body fully tightened by the manufacturer-approved method and tool
Sheath protection	No nicked conductors or excessive sheath removal; correct sheath insertion length through the connector
Cable withdrawal check	Cable cannot be withdrawn from the connector under the approved hand check
Cable support	Required cable support installed outside the box at the code- and product-controlled location
Closure of unused openings	Every unused knockout closed with a listed closure plug

F. Enclosure Review and De-Energized Verification

1. Review the enclosure type, wiring method, cable or raceway type, conductor count, connector listing, environmental rating, and grounding requirement. Record these on the Knockout and Connector Verification Worksheet before proceeding.
2. Verify that the enclosure is disconnected from all power sources. Apply the Chapter 1 lockout and verified de-energization procedure if the enclosure is or could become part of an energized system.
3. Inspect the enclosure for sharp edges, corrosion, missing parts, damaged threads, and prohibited openings. Correct or replace the enclosure before proceeding if any defect is found.

G. Cable-Entry Planning

1. Plan cable-entry locations to preserve conductor bending space, box fill, grounding hardware, device clearance, and cover installation. Mark each planned entry location on the enclosure before removing any knockout.
2. Select the correct knockout size for each listed connector. Confirm the connector's listed knockout size against the enclosure's knockout markings before proceeding.

H. Knockout Removal

1. Support the enclosure on a stable work surface. Confirm the enclosure cannot shift or roll during knockout removal.
2. Remove the selected knockout using the approved punch, knockout tool, or controlled hand-tool procedure. Follow the tool manufacturer's instructions for setup and operation.
3. Remove only the intended knockout and protect adjacent concentric rings. Stop immediately if an adjacent ring begins to loosen or deform.
4. Deburr the opening without enlarging or deforming it. Inspect the opening under adequate light for remaining sharp edges before proceeding.

I. Connector Selection and Installation

1. Select a connector listed for the exact cable, raceway, conductor material, size range, and enclosure condition. Confirm the connector's marked listing against the project's wiring method and environmental requirement.
2. Disassemble the connector only as required by its instructions. Keep all removed parts identified and available for reassembly.
3. Insert the connector through the opening in the correct direction. Confirm the connector's orientation matches its listed installation method.
4. Install and tighten the locknut, bushing, or threaded body using the approved tool and seating method. Confirm full engagement before proceeding.
5. Orient connector screws or clamps for access. Position the connector so its clamp screws remain reachable after the cable is installed.

J. Cable Preparation and Insertion

1. Prepare the cable end without nicking conductors or removing excessive sheath. Inspect the prepared end under adequate light before inserting it into the connector.
2. Insert enough sheath through the connector to satisfy the listed installation and box requirements. Confirm the sheath insertion length against the connector manufacturer's instructions.
3. Tighten the connector clamp evenly without crushing the cable or damaging insulation. Inspect the sheath immediately after tightening for deformation.
4. Verify that the cable cannot be withdrawn under the approved hand check. Apply a firm, steady hand-pull without force sufficient to damage the cable.

K. Cable Support and Enclosure Closure

1. Install the required cable support outside the box at the code- and product-controlled location. Confirm the support point matches the connector and cable manufacturer's stated distance.
2. Close unused openings with listed closures. Confirm each closure plug is fully seated and cannot be dislodged by hand.

L. Inspection and Correction

1. Inspect connector seating, locknut engagement, sheath protection, cable support, grounding continuity, and environmental rating. Complete every item on the Acceptance Standards table before concealment.
2. Replace any distorted knockout, damaged connector, or crushed cable. Do not conceal or proceed past a failed item; correct it and repeat the affected inspection step.