What Is a Deep Knock-Out Junction Box? Sizes and Selection Criteria
A deep knock-out junction box is a surface-mounted opaque ABS box deeper than a standard box of the same base, with cable entries opened by breaking out knock-outs.
A deep knock-out junction box is a surface-mounted ABS connection box with an opaque cover that is deeper than a standard box of the same base size; its cable entries are opened by breaking out the knock-outs on the body. It is used at splice and distribution points where thick cables must be bent, terminal blocks are stacked, or standard depth is not enough.
Types of deep junction boxes
| Type | Cable entry | Difference |
|---|---|---|
| Deep knock-out box | Entries come closed and are broken out during mounting | Only the needed entries are opened; the body is not drilled elsewhere |
| Deep plugged box | Entries come closed with plugs; the plug is removed to pass the cable | Unused entries stay closed with their plugs |
| Standard-depth box | Same base, shallower body | Enough for few joints and thin cables |
Çetinkaya Pano makes its knock-out boxes of the same base in two depths:
| Base (mm) | Standard knock-out | Deep knock-out |
|---|---|---|
| 80x120 | 50 mm (`ÇP 1239`) | 120 mm (`ÇP 1259`) |
| 100x100 | 50 mm (`ÇP 1240`) | 120 mm (`ÇP 1260`) |
| 150x110 | 70 mm (`ÇP 1251`) | 140 mm (`ÇP 1261`) |
| 190x145 | 80 mm (`ÇP 1252`) | 140 mm (`ÇP 1262`) |
| 250x200 | 90 mm (`ÇP 1253`) | 160 mm (`ÇP 1263`) |
| 310x230 | 130 mm (`ÇP 1254`) | 180 mm (`ÇP 1264`) |
Selection criteria
- Depth: The third figure in the size is the depth. Choose a deep model for thick cables, stacked terminal blocks or a tall device inside the box.
- Base size: Chosen by the number of connections and terminal blocks; the joints must fit without squeezing and the cover must close without force.
- Number and diameter of entries: Open only the knock-outs you will use; the opened entry must match the conduit or gland diameter.
- Environment: The product names give no IP rating. Before using the box in a damp or dusty place, confirm the IP value on the product page and fit suitable glands in the opened entries.
Common mistakes
- Opening more knock-outs than needed: An opened entry cannot be closed again; an empty hole lets dust and water into the box.
- Cracking the body when breaking a knock-out: Break it out from its edge without putting load on the body.
- Enlarging the base instead of the depth: If the problem is bending the cables, a deeper box, not a wider one, solves it.
- Mixing up knock-out and plugged models: Both exist in the same sizes; check the entry type in the product name before ordering.
Deep knock-out junction boxes in the Welibaba catalogue
The Surface-Mounted Deep Opaque Junction Boxes category has 6 active products, all Çetinkaya Pano knock-out deep opaque ABS boxes (`ÇP 1259`–`ÇP 1264`) sold per piece. The sizes are in the table above.
Plugged models of the same sizes (`ÇP 1359`–`ÇP 1364`) are in Surface-Mounted Deep Junction Boxes with Plugs; Çetinkaya deep opaque boxes whose names mention neither knock-out nor plugs (`ÇP 1059`–`ÇP 1065`) and the standard-depth models are in Surface-Mounted Opaque Junction Boxes; joint terminal blocks are in Junction Box Terminal Blocks.
Frequently asked questions
What is the difference between a deep knock-out and a deep plugged junction box?
In a knock-out box the entries come closed and are broken out during mounting. In a plugged box the entries are closed with plugs; the plug is removed and the cable passed through. The sizes are the same; only the cable entry differs.
When is a deep junction box needed?
When cables cannot be bent in a standard box, terminal blocks will be stacked, or a tall device goes inside. For example, on a 150x110 mm base the standard knock-out box is 70 mm deep and the deep model 140 mm.
Which figure in the size is the depth?
The third one. A 250x200x160 mm box has a 250x200 mm base and a depth of 160 mm.
Can I close a knock-out I have opened?
The broken piece cannot be refitted. If an entry you will not use has been opened, close it with a blanking plug or a gland.