When your control panel runs out of space, add an enclosure only when the added equipment forms a serviceable, electrically defined group. Redesign the existing layout when crowding already compromises cooling, wiring space, approved mounting orientation, or access. A second box should solve a capacity problem, not relocate it. Start with the installed equipment and the expected expansion, then compare both arrangements against the same requirements.
Decide whether another enclosure solves the problem
Separate equipment that merely needs more mounting area from equipment that needs a different electrical or thermal arrangement. Remote I/O, network equipment, or a distinct machine subsystem may suit an adjacent enclosure. Components with many short interconnections may be better consolidated in a larger cabinet.
| Check | An added enclosure can work when | Redesign or replacement is stronger when |
|---|---|---|
| Functional grouping | Equipment serves a defined subsystem | Equipment must be scattered between boxes |
| Interconnections | Cable quantities, lengths, and entries remain manageable | Numerous conductors require large ducts or penetrations |
| Heat | Each enclosure has a documented thermal solution | Existing equipment already exceeds temperature limits |
| Maintenance | Both boxes remain accessible and clearly isolated | One box obstructs another or creates hidden live supplies |
| Expansion | Each assembly retains defined usable capacity | The addition consumes the last practical installation space |
Do not count a sidewall, roof, or door as spare mounting area without checking the complete installation. Equipment installed there still needs support, wiring access, bonding where required, and its documented clearances.
If the existing arrangement already fails those checks, redrawing the backplate may recover useful space. Replacement becomes the better choice when the corrected layout still cannot fit.
Match the enclosure to the actual environment
An adjacent enclosure does not necessarily experience the same conditions as the original cabinet. Its proposed location may receive direct washdown, outdoor sunlight, coolant spray, or chemical deposits.
Record the exposure at the new mounting position before choosing the enclosure:
- Water: sheltered drips, rain, hose-directed cleaning, or a more demanding cleaning process.
- Dust: airborne deposits and whether maintenance opens the door in a dirty area.
- Chemicals: cleaning agents, concentration, temperature, contact time, and rinse practice.
- Temperature: maximum local ambient, nearby process heat, and direct solar exposure.
- Moisture: temperature cycling, humid air introduced during service, and possible condensation.
Moving a network device outside a crowded cabinet may reduce the original heat load. It also exposes that device to a different environment and requires suitable cable entries and power arrangements.
For outdoor installations, distinguish environmental protection from wiring suitability using the article on outdoor panel wet-location ratings and wiring limits. Neither a larger cabinet nor an additional cabinet eliminates those requirements.
Select the rating and approval path first
Choose the enclosure type for the exposure, rather than matching the label on the nearest existing box. Indoor dust protection, hose-directed water, and corrosion resistance are different requirements under NEMA 250.
Our wall-mount enclosures are manufacturer-rated NEMA 4X-type / IP66; not UL listed. Confirm whether the project requires an enclosure listing, an evaluated completed panel, or another approval route before ordering.
For a modified listed assembly, determine how the proposed changes affect its evaluation and marking. Do not assume an enclosure addition automatically preserves or cancels the existing approval. The unlisted enclosure approval-path article addresses that separate decision.
Specify the required rating for the completed arrangement, including cable glands, plugs, cooling equipment, and door-mounted devices. An enclosure rating does not establish the suitability of every installed accessory.
A high-pressure or hot washdown application needs review against the actual cleaning conditions. Do not treat ordinary hose-directed-water protection as evidence for every cleaning process.
Choose material for the new mounting position
For general indoor washdown and many outdoor installations, 304 stainless steel is a practical starting point. Consider 316L stainless steel where salt air, brine, or chloride exposure makes additional corrosion resistance necessary.
Neither grade establishes universal chemical compatibility. Check the cleaning chemicals against the enclosure, gasket, glands, fasteners, and any viewing window. Moving equipment into a chemically exposed location can make material selection more demanding than the original installation.
For custom work, powder-coated carbon steel can suit indoor and sheltered industrial panels. The choice should follow the exposure and project specification, not simply the appearance of the original cabinet.
Also consider the installation support. A larger enclosure carries the combined weight of its backplate, components, conductors, and door equipment. An adjacent enclosure needs its own suitable mounting arrangement; cable or conduit connections are not structural supports.
Measure usable capacity instead of empty rectangles
Build a revised layout using component envelopes, required clearances, wiring ducts, terminals, and service access. The enclosure sizing guide covers the underlying dimensional checks; the expansion decision needs a comparison of complete layouts.
Use the following sequence for both alternatives:
- Record the existing equipment and every planned addition, including auxiliary power supplies and interface terminals.
- Confirm each device's permitted orientation, spacing, and temperature limits from its current manufacturer documentation.
- Draw the backplate with duct, conductor bending space, termination access, and component removal paths.
- Add door-mounted equipment envelopes and the moving space needed by its wiring.
- Reserve defined capacity for the next expansion, then check the installed arrangement again.
Do not rotate a controller or power supply solely to make its outline fit. A permitted alternative orientation may have a lower ambient limit or require different clearances. A customer layout preference does not replace those conditions.
Define spare capacity by category. Free backplate area, spare rail length, terminal positions, I/O channels, power capacity, and thermal margin are separate quantities.
For example, if the completed layout occupies 400 square inches and the project requires 20% free usable area, the planning area is 500 square inches: 400 divided by 0.80. This is a project planning allowance, not a universal code requirement. It does not replace clearances or duct capacity.
The backplate and DIN rail layout guide explains those layout fundamentals. Request the actual mounting-panel drawing rather than treating outside enclosure dimensions as usable backplate dimensions.
Check the heat in both proposed arrangements
More empty space does not prove adequate cooling. Calculate the losses inside each proposed enclosure at the expected operating load and maximum local ambient.
An illustrative existing panel dissipates 120 W. Moving a group dissipating 30 W leaves approximately 90 W in the original enclosure before accounting for changed power supplies or interface equipment. The added enclosure must still reject its own 30 W and any additional losses.
Check the local temperature around sensitive equipment, not only the average enclosure air temperature. A controller positioned above a heat-producing device may experience a hotter inlet than the cabinet average.
The article on component layout inside a sealed enclosure addresses those internal heat paths. Keep required air passages clear, and verify any temperature derating associated with orientation or adjacent mounting.
A larger enclosure may improve passive heat rejection, but mounting position and exposed surface area matter. A box closely surrounded by equipment does not exchange heat like an unobstructed box.
After selecting a thermal solution, check the resulting enclosure rating, maintenance needs, and condensation risk. Do not solve crowding by adding unreviewed ventilation openings.
Keep wiring and maintenance practical
Plan modification work under the site's electrical safety procedures, with isolation and verification before access or alterations. An added cabinet can introduce multiple supplies or backfeed paths that require explicit identification and isolation provisions.
For a satellite enclosure, document the power source, protective devices, disconnecting arrangements, grounding, and interconnecting cables. Review any effect on fault protection, short-circuit current rating, and the applicable assembly approval.
Bond exposed conductive parts as required. Follow the enclosure grounding and bonding guide rather than assuming mounting screws or an incidental conduit connection provide every required bonding path.
Locate cable entries where conductors can reach their terminals without violating bending space or obstructing equipment removal. Provide enough wall area for gland installation, tightening, and future cable replacement.
Door-mounted or side-mounted components need special attention. Check door travel, flexible wiring movement, access to fasteners, and clearance with the door closed. The installed drawing must show these components, not just the main backplate.
Where required, preserve working space and sufficient door opening under NEC 110.26(A). A second enclosure placed beside the first can obstruct service even when both backplates look acceptable.
Put the capacity decision on the order
Compare catalog candidates only after the functional, dimensional, thermal, and approval checks are complete. The enclosure selector can then help narrow the dimensional choice; it does not establish thermal suitability.
A 24 x 20 x 8 in 304 stainless wall-mount enclosure is one candidate for an added subsystem. Its nominal inside dimensions are 23.88 x 19.88 x 7.88 in, expressed as height x width x depth. Verify mounting-panel area and panel-to-door clearance separately.
For consolidation, a 36 x 30 x 12 in 304 stainless wall-mount enclosure provides a different starting envelope. Its nominal inside dimensions are 35.84 x 29.84 x 11.84 in. Neither example is a capacity recommendation without the completed layout and heat assessment.
When neither candidate suits the installation, we build custom enclosures with your specified material, width, height, depth, and cutouts, from one piece.
| Order requirement | What to state |
|---|---|
| Architecture | Adjacent subsystem enclosure or consolidated replacement, with equipment allocated to each |
| Environment | Water, dust, chemicals, sunlight, and maximum local ambient |
| Rating and approval | Required enclosure type, accessory protection, and assembly approval requirements |
| Material | Grade and finish, supported by the actual exposure |
| Usable dimensions | Mounting-panel dimensions, component clearances, and panel-to-door space |
| Equipment arrangement | Device models, approved orientations, duct, terminals, and service envelopes |
| Thermal design | Losses per enclosure, temperature limits, and required cooling arrangement |
| Cable interfaces | Cable quantities, diameters, entry positions, glands, and termination space |
| Mounting and bonding | Support arrangement, installed weight, door travel, and bonding provisions |
| Expansion allowance | Defined spare area, rail, terminals, I/O, power, and thermal capacity |
| Drawing approval | Dimensioned layout showing backplate, sidewall, and door-mounted equipment |
Resolve any conflict between the approved device installation requirements and the proposed layout before approving the enclosure drawing.
Enclosures in this article
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 24 × 20 × 8 in | 304 stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 36 × 30 × 12 in | 304 stainless | 36 x 30 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Can you rotate a controller to recover backplate space?
Only when the device manufacturer permits that mounting orientation and you meet its associated temperature and clearance requirements. Some devices require derating in alternative orientations. Check the exact model documentation before changing the layout, and include the permitted arrangement on the approved drawing.
When is adding another enclosure better than replacing the existing one?
An adjacent enclosure works best when it contains a defined subsystem with manageable interconnections and independent service access. It still needs a suitable power arrangement, bonding, cable entries, environmental protection, and thermal assessment. Redesign the original panel if its existing crowding already violates installation requirements.
Is 20% spare panel space enough?
A percentage can be a useful project requirement, but it is not a complete expansion specification. Define usable backplate area, rail length, terminals, I/O channels, power capacity, duct capacity, and thermal margin separately. Spare mounting area cannot compensate for inadequate component clearances or wiring space.
Can components be mounted on the enclosure sidewalls?
Sidewall mounting can be acceptable when the equipment installation instructions and enclosure arrangement support it. Show the equipment on the drawing and check support, orientation, bonding, wiring access, cooling, and removal space. Do not count sidewalls as usable spare area without reviewing those conditions.
Will a larger enclosure automatically solve overheating?
A larger enclosure may reject more heat, but adequate cooling depends on component losses, ambient temperature, mounting conditions, and exposed surface area. Internal arrangement also affects local temperatures. Complete the thermal assessment separately from the dimensional layout before selecting a larger enclosure.
