Only a single drainage opening, not larger than 6 mm (1/4 in. ), is to be drilled in a box or conduit body unless instructed by the manufacturer. The bolt length is generally the sum of the embedded depth (75-150 mm), the thickness of the box bottom plate, the thickness of the nut and. When running electrical conduit into panels, junction boxes, or enclosures, choosing the correct hole size is one of the most overlooked details. According to the NEC, the recommended hole size for a 1 2 knockout is 7/8 of an inch (22. However, it's essential to understand the implications and potential risks involved. For installations of listed drain fittings, larger openings are permitted to. Mark and drill holes → fix box with expansion bolts. Keep box level and stable; use waterproof type if outdoors. Wiring Connections Strip wires → connect to terminals (phase, neutral, ground) → arrange neatly.
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