A precise length is necessary both to allow for connection and to manage the physical volume of the box. Electrical safety standards specify that at least 6 inches of free conductor must be left at each outlet, junction, or switch point. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Connection method: Each switch takes a wire from the incoming point and connects it to the incoming end of the switch, or uses parallel connection to reduce the difficulty of wiring. Choosing the right distribution box depends on factors like the size of the installation, the number of circuits. The length of the bolts is generally the sum of the embedded depth (75-150 mm), the thickness of the box bottom plate, the thickness of the nuts and washers, plus the "overhanging allowance" of about 5 mm. For smaller distribution boxes, wood bricks can also be embedded at the installation place.
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