It also prevents the cable from rubbing against the edge of the box and potentially damaging the sheathing.
Most plastic boxes have built-in spring tabs that secure the cable as it’s pushed into the box.
Look on the side of the box and locate the knockout where you want to install your cable.
The Spruce / Kevin Norris
Some knockouts have a straight slot in their center.
Another punch in of knockout has no slot and must be punched out with a hammer and screwdriver.
Grab the knockout disc with pliers and twist it until it comes free.
Usually, there are two clamps that can hold two cables each.
There should be a pre-drilled hole for the clamp screw near each pair of knockouts.
Insert the cable into the knockout and slide it under the clamp.
Tighten the clamp’s screw to secure the cable.
Tighten the nut with pliers.
Tip
Orient the clamp so the saddle screws are facing you.
This makes it easy to tighten the screws when installing the cable.
Using Plastic Push-In Connectors
The newcomer on the block is the plastic push-in connector.
The cable is inserted through the connector and secured with a spring-tab or other rig.
National Fire Protection Association.
