Electrical Box Knockout Sizes

These boxes protect wiring from the elements with gaskets sealed seams and watertight covers.

Electrical box knockout sizes.

Hydraulic with piece maker. Trade size in 1 1 2 57 1 1 4 62 1 2 152 1 93 2 1. I know that i will need to drill with hole saws or use a knockout punch in junction boxes and the circuit breaker panel. But sometimes the standard knockout openings in a wall box aren t large enough for the cable clamp or conduit fitting you need to attach to the box so you have to enlarge the hole.

Knockout holes or knockouts in electrical boxes are made at the factory and have standard sizing to match cable clamps. Knockout non metallic push in connector. Different electrical box sizes fit varying installation needs. For example if you have a 7 8 hole you ll need a 1 2 knockout plug.

Notes to the table above. An example is 1 2 inch 1 3 cm trade size. Knockout type conduit size hole range part number page no. A standard rectangular shape is the most common electrical box.

Electrical trade sizes and plumbing trade sizes are equal and are based on pipe sizes. 1 2 to 2 179pm. I have posted the hole saw and knockout sizes for electrical conduit below. 1 2 to 2 152.

12 awg is larger than 14 awg so a box can have fewer 12 awg conductors than 14 awg. 1 1 2 to 2 159pm. What are the actual hole saw sizes for the various trade sizes of electrical conduit. 1 2 to 1 1 4 158pm.

It houses a single electrical switch or outlet and comes in metal or nonmetallic units. 1 2 to 4 154. 1 2 to 2 157pm. Here are the maximum box fill limits for a few common sizes of electrical boxes.

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. Hydraulic punch driver straight 90 deg. 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. I plan to install a lot of electrical conduit.

First determine the size of the missing knockout hole and subtract 3 8 to figure out what size knockout plug you ll need. The 3 4 inch 1 9 cm trade size is a 1 1 8 inch 2 9 cm opening.