Electrical Box Punch Out Sizes

An example is 1 2 inch 1 3 cm trade size.

Electrical box punch out sizes.

For example if you have a 7 8 hole you ll need a 1 2 knockout plug. Notes to the table above. It houses a single electrical switch or outlet and comes in metal or nonmetallic units. The outlet addition methods we show here are based on the most common wiring 14 gauge wire on a 15 amp circuit and an 18 cu in.

To determine the actual opening for this size you need to add 3 8ths of an inch which is 7 8ths of an inch opening. The 3 4 inch 1 9 cm trade size is a 1 1 8 inch 2 9 cm opening. The national electrical code article 314 contains complete details and tables of electrical box sizes in dimensions and cubic inches and should be consulted for complete accuracy because the actual size of the box required in cubic inches depends on the number of wires that will be within that enclosure. If you punch out too big of a hole you can use reducing washers.

First knockout punched inward for removal. Codes also limit the number of wires that can enter an electrical box or electrical receptacle depending on the inside volume of the box and the gauge of the wires. Bx cutters after cutting out some concentric knockouts. A pilot hole is drilled into the box as needed then a draw bolt and die are inserted into the hole and a punch is threaded onto the draw bolt.

The draw bolt is turned by a wrench to pull the punch through the metal making the hole. Different electrical box sizes fit varying installation needs. Mophorn 10 ton 1 2 to 2 hydraulic knockout punch driver tool kit electrical conduit hole cutter set ko tool kit with 6 dies hole complete tool knockout punches by mophorn 71 99 71. Standard piece makertm punch and conduit size actual punched hole diameter in 1560.

Box typical inside dimensions are about 2 in. If you punch out the wrong hole you can fill it with a knockout seal. In the electrical panel above the inner 3 4 knockout was the easiest to punch out first. The shape of an electrical box can help you identify its purpose.

A screw type or manual knockout punch is tightened with a wrench to knock out the hole. A standard rectangular shape is the most common electrical box.