Electrical Box Punch Out Sizes

Standard piece makertm punch and conduit size actual punched hole diameter in 1560.

Electrical box punch out sizes. First knockout punched inward for removal. The 3 4 inch 1 9 cm trade size is a 1 1 8 inch 2 9 cm opening. In the electrical panel above the inner 3 4 knockout was the easiest to punch out first. If you punch out too big of a hole you can use reducing washers.

The shape of an electrical box can help you identify its purpose. 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. If you punch out the wrong hole you can fill it with a knockout seal. 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.

Electrical trade sizes and plumbing trade sizes are equal and are based on pipe sizes. Different electrical box sizes fit varying installation needs. It houses a single electrical switch or outlet and comes in metal or nonmetallic units. For example if you have a 7 8 hole you ll need a 1 2 knockout plug.

A standard rectangular shape is the most common electrical box. 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. Notes to the table above. Box typical inside dimensions are about 2 in.

Temco th0390 manual knockout punch driver kit set for inch to 2 inch electrical conduit hole sizes 1 2 2 conduit size 4 7 out of 5 stars 56 84 95 84. The draw bolt is turned by a wrench to pull the punch through the metal making the hole. 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. 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.

An example is 1 2 inch 1 3 cm trade size. Bx cutters after cutting out some concentric knockouts.