Industrial Enclosures Explained: IP Ratings, Materials, Sizing and Outdoor Cabinets

Quick overview: This guide explains industrial enclosures and the practical checks that help you understand and plan an installation. Use the contents below to go directly to the relevant section.

An industrial enclosure does much more than provide a box around electrical or automation equipment. It protects components from the surrounding environment, supports safe installation and maintenance, provides space for wiring and cable termination, and can have a major effect on equipment temperature and reliability.

Choosing an enclosure only by its outside dimensions can create problems later. The installation environment, ingress protection, material, heat load, cable entry, internal component clearances, mounting method, corrosion exposure, ventilation and future expansion all need to be considered.

This guide explains how industrial enclosures are specified for electrical distribution, automation, networking, instrumentation and outdoor infrastructure applications.

What Is an Industrial Enclosure?

An industrial enclosure is a cabinet, box or housing designed to contain and protect electrical, electronic, automation, networking or instrumentation equipment.

Depending on the application, an enclosure can contain:

• PLCs and remote I/O
• VSDs and soft starters
• Circuit breakers and contactors
• 24 VDC power supplies
• Industrial Ethernet switches
• Fibre equipment
• Terminal blocks
• Relays
• Instrumentation interfaces
• UPS equipment
• Telemetry and communication equipment

Why Enclosure Selection Matters

The equipment inside a panel can be correctly selected and still fail prematurely if the enclosure is unsuitable.

Common enclosure-related problems include:

• Water ingress
• Dust contamination
• Excessive internal temperature
• Condensation
• Corrosion
• Insufficient wiring space
• Poor cable access
• Restricted airflow
• UV degradation
• Difficult maintenance access

Enclosure specification should therefore form part of the equipment design rather than being treated as a final packaging decision.

What Is an IP Rating?

IP stands for Ingress Protection.

An IP code indicates the degree of protection provided by an enclosure against access to hazardous parts, solid foreign objects and water under defined test conditions.

A typical rating is written as:

IP65

The first digit relates to protection against solid objects and access, while the second digit relates to water ingress.

Understanding the First IP Digit

The first numeral describes protection against access and solid foreign objects.

Higher numbers generally indicate greater protection, with ratings commonly encountered in industrial equipment ranging up to dust-tight construction.

The exact definition of each rating should be checked against the applicable IEC standard rather than interpreted only as a marketing term.

Understanding the Second IP Digit

The second numeral describes protection against water under specified test conditions.

Different ratings address conditions such as dripping water, spraying, water jets and temporary or continuous immersion.

A higher number does not mean the enclosure is suitable for every possible environmental exposure. The nature of the test and installation still matter.

IP54

IP54 enclosures are commonly used in industrial environments where protection against dust ingress and splashing water is required but the application does not demand a fully dust-tight enclosure.

Suitability depends on the actual location and equipment inside.

IP65

IP65 is common for industrial cabinets requiring dust-tight construction and protection against water jets under the standard's defined test conditions.

It is frequently specified for outdoor or dusty environments, but IP65 alone does not address UV exposure, corrosion, solar heat gain or condensation.

IP66

IP66 provides dust-tight protection and a higher defined water-jet protection level than IP65.

It can be useful for harsher outdoor and industrial conditions where stronger water exposure is expected.

Actual suitability still depends on enclosure construction and site conditions.

IP67 and Immersion

IP67 includes protection against temporary immersion under defined conditions.

This does not mean an enclosure can be installed permanently underwater unless it has an appropriate rating and is designed for that service.

Cable glands, connectors and modifications must also maintain the required protection.

IP Rating Is a Complete Assembly Issue

An enclosure may leave the factory with a specified IP rating, but modifications can affect that rating.

Examples include:

• Door-mounted HMIs
• Pushbuttons
• Fans
• Filters
• Cable glands
• Breather drains
• Unused holes
• Poorly sealed gland plates

The completed panel should be considered as an assembly rather than assuming the empty enclosure rating automatically applies after fabrication.

IP Rating Does Not Mean Corrosion Resistance

Ingress protection and corrosion resistance are different characteristics.

A cabinet can provide excellent dust and water protection but still corrode rapidly if its material and coating are unsuitable for the environment.

Coastal, chemical, wastewater and mining environments can require additional material consideration.

IP Rating Does Not Mean Explosion Protection

An ordinary high-IP enclosure is not automatically suitable for hazardous areas containing flammable gases, vapours or combustible dusts.

Hazardous-area equipment requires appropriate certification and installation according to the area classification and applicable standards.

IP rating alone is not evidence of explosion protection.

Common Industrial Enclosure Materials

Industrial cabinets are available in several materials, including:

• Painted mild steel
• Stainless steel
• Aluminium
• Polyester and other non-metallic materials

Each material has advantages and limitations.

Painted Mild Steel Enclosures

Painted mild steel is widely used for indoor electrical and automation panels.

Advantages can include:

• Mechanical strength
• Wide availability
• Ease of fabrication
• Cost effectiveness

The coating system is important because exposed or damaged steel can corrode in humid or aggressive environments.

Powder-Coated Steel

Powder coating provides a durable finished surface and is common on industrial cabinets.

Coating performance depends on surface preparation, coating chemistry, thickness and environmental exposure.

Cut edges and drilled holes created during fabrication should be treated appropriately where corrosion protection is required.

Stainless Steel Enclosures

Stainless steel is used where corrosion resistance, washdown capability or hygiene requirements make painted mild steel less suitable.

Common applications include:

• Food and beverage environments
• Water and wastewater plants
• Selected outdoor installations
• Corrosive process environments

The correct stainless grade depends on the exposure.

304 vs 316 Stainless Steel

304 stainless steel is widely used for general industrial corrosion resistance.

316 stainless steel contains molybdenum and generally offers improved resistance in chloride-rich and more aggressive environments.

Neither grade is universally immune to corrosion. Site chemistry, temperature, surface finish and maintenance still matter.

Aluminium Enclosures

Aluminium provides relatively low weight and natural corrosion resistance and is used for selected electrical, electronic and outdoor applications.

Material compatibility, coating, galvanic corrosion and mechanical requirements should be considered where aluminium is combined with other metals.

Non-Metallic Enclosures

Polyester and other engineered non-metallic enclosures can provide corrosion resistance and electrical insulation.

They are useful in some outdoor, chemical and telecommunications applications.

Selection should consider UV stability, impact resistance, temperature limits, fire performance and electromagnetic shielding requirements.

Metal vs Non-Metallic Enclosures

Metal cabinets provide mechanical strength and can assist with electromagnetic shielding and protective bonding.

Non-metallic cabinets can avoid corrosion and provide electrical insulation but can behave differently in terms of heat dissipation and EMC.

The correct choice depends on the equipment and environment.

Wall-Mounted Enclosures

Wall-mounted cabinets are common for smaller control, instrumentation and network systems.

Applications include:

• PLC panels
• Remote I/O stations
• Small VSD panels
• Telemetry panels
• Fibre termination
• Industrial networking

Wall strength, mounting height, cable access and service clearance should be considered.

Floor-Standing Enclosures

Floor-standing cabinets provide greater internal volume and are common for larger control and distribution systems.

They can accommodate:

• Multiple VSDs
• Large PLC systems
• Motor starters
• Power distribution
• Network and server equipment

Plinths, lifting, transport and floor anchoring become important as enclosure size and weight increase.

Modular Enclosure Systems

Modular cabinets allow multiple enclosure bays to be joined into larger assemblies.

They are useful for MCCs, large automation panels and switchboards where equipment needs to be divided into functional sections.

Joining kits, internal separation, busbar systems and door arrangements should be considered as part of the complete assembly.

Junction Boxes

Junction boxes provide protected termination and interconnection points for field wiring.

They can be used for:

• Instrumentation
• Motor wiring
• Sensor connections
• Marshalling
• Network or fibre termination

Terminal quantity, cable entry, earthing and environment influence junction-box sizing.

Marshalling Enclosures

Marshalling cabinets organise field signals between process equipment and control systems.

They can contain large numbers of terminal blocks, fuses, isolators, signal conditioners and surge protection devices.

Clear labelling and wiring access are particularly important in high-density marshalling applications.

Network Cabinets and Racks

Industrial network equipment can be housed in wall-mounted cabinets, floor-standing racks or industrial enclosures.

Typical equipment includes:

• Industrial Ethernet switches
• Patch panels
• Fibre trays
• Routers
• UPS equipment
• Power distribution units

Cabinet depth, rack-unit capacity, ventilation and cable management are important selection factors.

19-Inch Rack Cabinets

Many networking and communications products use the standard 19-inch rack format.

Rack cabinets are commonly specified by rack units, or U.

One rack unit represents a standard vertical mounting increment. The total U requirement should include equipment, patching, cable management and reasonable spare capacity.

Industrial Network Enclosures

Not all industrial networking equipment is rack mounted.

DIN rail switches, routers, fibre media converters and power supplies are often installed in electrical-style enclosures closer to machinery or field infrastructure.

These cabinets require the same attention to temperature, power, grounding and environmental protection as control panels.

Outdoor Telecom and Fibre Cabinets

Outdoor communication cabinets can house:

• Fibre termination equipment
• Industrial switches
• Routers
• PoE equipment
• DC power supplies
• UPS or batteries

Outdoor network cabinets require particular attention to solar heat gain, condensation, surge protection, cable entry and antenna or fibre routing.

Outdoor Electrical Cabinets

An outdoor cabinet should be selected for the actual exposure rather than simply choosing a high IP number.

Important considerations include:

• Rain direction
• Windblown dust
• Solar radiation
• Ambient temperature
• Humidity
• Condensation
• Corrosion
• UV exposure
• Insects and vermin
• Security and vandalism

Solar Heat Gain

Direct sunlight can raise enclosure surface and internal temperatures significantly above the surrounding air temperature.

This can cause PLCs, VSDs, power supplies, batteries and network equipment to operate outside their permitted temperature range.

Outdoor thermal design should therefore account for solar loading.

Sunshields

A sunshield creates an additional barrier between direct solar radiation and the enclosure surface.

Depending on the design, it can reduce solar heating while allowing air movement around the main cabinet.

Sunshields can be particularly useful for exposed outdoor control and telemetry installations.

Double-Skin Enclosures

Double-skin construction uses an outer layer separated from the main enclosure.

This can reduce direct solar heat transfer and provide additional environmental protection.

The actual thermal benefit depends on construction, ventilation and installation conditions.

Condensation Inside Enclosures

Condensation occurs when a surface temperature falls below the dew point of the air inside the enclosure.

Outdoor cabinets can experience condensation even when no rainwater enters the enclosure.

Temperature cycling between warm days and cool nights is a common cause.

Why Condensation Is Dangerous

Moisture inside a panel can cause:

• Corrosion
• Insulation deterioration
• Short circuits
• Connector problems
• Network faults
• Instrumentation errors

Moisture management is therefore a reliability issue as well as an ingress-protection issue.

Anti-Condensation Heaters

Small enclosure heaters can maintain internal temperature above the dew point during cold or humid conditions.

They are often controlled by thermostats or hygrostats.

Heater placement and rating should avoid overheating adjacent equipment.

Hygrostats

A hygrostat switches equipment such as heaters or fans according to relative humidity.

This can provide more targeted condensation control than temperature-only control in suitable applications.

Breather Drains

Breather or drainage devices can help manage pressure equalisation and accumulated moisture in appropriately designed enclosures.

They should be selected to maintain the required environmental protection and installed according to manufacturer instructions.

Thermal Management

Every active electrical component produces some heat.

Common heat sources include:

• VSDs
• Soft starters
• Power supplies
• Transformers
• PLCs
• Industrial Ethernet switches
• UPS equipment

Enclosure temperature depends on heat generation, cabinet surface area, ambient temperature, material, airflow and cooling method.

Natural Convection

Some low-heat panels can dissipate sufficient heat through the enclosure surfaces without active cooling.

This has the advantage of avoiding fans and filters, which can reduce maintenance and help preserve enclosure sealing.

Thermal calculations should confirm whether passive cooling is adequate.

Filtered Fan Cooling

Filtered fans move ambient air through the cabinet.

They can provide economical cooling when the surrounding air is sufficiently clean and cool.

Filters require maintenance, and adding ventilation openings changes the environmental protection of the enclosure.

Air Conditioners

Enclosure air conditioners provide closed-loop cooling and can be useful where the surrounding air is hot, dusty or contaminated.

Cooling capacity should be based on:

• Internal heat load
• Ambient temperature
• Required internal temperature
• Solar loading where applicable
• Enclosure dimensions

Condensate drainage and maintenance access also need to be planned.

Heat Exchangers

Air-to-air or air-to-water heat exchangers can transfer heat while maintaining separation between internal and external air.

They can be useful where contamination prevents direct ventilation.

The suitability of each type depends on site utilities and environmental conditions.

Enclosure Sizing

Enclosure sizing should start with the equipment layout, not simply the combined dimensions of the devices.

Space is needed for:

• Component clearances
• Wiring ducts
• Terminal blocks
• Cable bending
• Cooling airflow
• Door-mounted equipment
• Maintenance access
• Future expansion

Why an Overcrowded Panel Is a Problem

Overcrowding can cause:

• Higher temperatures
• Difficult wiring
• Poor airflow
• Reduced service access
• Incorrect component clearances
• Greater risk of wiring errors

A physically smaller cabinet is not necessarily the lowest-cost solution over the life of the system.

Mounting Plates

A mounting plate provides a surface for installing DIN rail, wiring duct, drives, transformers and other components.

Plate thickness and material should suit the equipment weight and mounting method.

Large components should be mechanically supported according to manufacturer requirements.

DIN Rail Layout

DIN rail is widely used for modular control equipment.

Rail spacing should allow room for wiring and should respect component ventilation requirements.

Devices that generate significant heat should not be placed where they unnecessarily heat temperature-sensitive equipment.

Wiring Duct

Wiring duct organises internal conductors and helps keep the panel maintainable.

Duct should be sized for the expected cable population rather than packed completely full at initial installation.

Additional capacity can make future modifications easier.

Cable Bending Radius

Large power cables and fibre optic cables require minimum bending radii.

A cabinet can appear large enough for the equipment but still be too shallow or too narrow to terminate cables correctly.

Cable type and entry direction should therefore be known during enclosure sizing.

Cable Entry

Common cable-entry arrangements include:

• Bottom entry
• Top entry
• Side entry
• Rear entry in suitable cabinets

The selected arrangement should suit site cable routing and internal termination locations.

Gland Plates

Gland plates provide a dedicated area for cable entry and can simplify fabrication and installation.

They can be removable or fixed depending on enclosure design.

The plate must provide sufficient space for cable glands while maintaining mechanical strength and environmental sealing.

Cable Glands

Cable glands secure cables and can provide sealing, strain relief and, for suitable metallic or armoured cable systems, earthing or shielding functions.

Selection can depend on:

• Cable diameter
• Cable armour
• Thread type
• Enclosure material
• IP requirement
• Environmental exposure

Unused Cable Entries

Unused holes should be closed using suitable blanking devices.

An open or poorly sealed unused entry can defeat the environmental protection of the entire cabinet.

Door-Mounted Equipment

HMIs, pushbuttons, selector switches, lamps and meters are often mounted on enclosure doors.

Door layout should consider:

• Operator ergonomics
• Internal clearance
• Door weight
• Wiring movement
• Environmental sealing

Door-mounted devices should have suitable ratings for the required enclosure protection.

Viewing Windows

Viewing windows allow operators to see meters, displays or indicators without opening the enclosure.

The window and its installation should maintain the required environmental protection and impact resistance.

Locks and Security

Industrial cabinets can use key locks, quarter-turn latches, padlockable handles or other access-control arrangements.

Outdoor and publicly accessible installations can require additional security against unauthorised access or vandalism.

Plinths

A plinth raises a floor-standing cabinet above the floor or foundation.

It can provide:

• Cable-entry space
• Mechanical support
• Improved clearance from standing water
• Easier installation

Outdoor plinths should be coordinated with the civil foundation and cable routes.

Canopies and Rain Hoods

Canopies can provide additional protection over doors, vents or cabinet openings.

They are often used on outdoor enclosures to reduce direct rain exposure.

The enclosure must still meet its required environmental rating without relying on assumptions about the canopy.

Floor and Foundation Requirements

Large cabinets should be installed on a suitable level foundation capable of supporting their weight.

Foundation planning can also include:

• Anchor bolts
• Cable trenches
• Conduits
• Drainage
• Access clearance

Lifting and Transport

Large enclosures and completed panels can become extremely heavy.

Lifting eyes, transport plinths, centre of gravity and internal component support should be considered before movement.

Manufacturer lifting instructions should be followed.

Protective Bonding of Metal Enclosures

Metal cabinets and conductive parts require appropriate protective bonding according to the electrical design.

Doors, gland plates and removable panels can require bonding where mechanical contact alone does not provide the required continuity.

EMC and Enclosures

Metal enclosures can form part of an electromagnetic compatibility strategy by providing shielding.

Effective EMC performance also depends on:

• Bonding
• Cable shielding
• Gland selection
• Panel layout
• Separation
• Filter installation

Simply placing equipment inside a metal box does not guarantee good EMC performance.

Corrosion in Industrial Environments

Corrosion risk depends on more than whether an enclosure is indoors or outdoors.

Aggressive conditions can include:

• Coastal salt exposure
• Chemical vapours
• Wastewater gases
• High humidity
• Mining dust and process chemicals
• Frequent washdown

Material and coating selection should match the actual exposure.

Galvanic Corrosion

When dissimilar metals are electrically connected in the presence of an electrolyte such as moisture, galvanic corrosion can occur.

This can be relevant where stainless steel, aluminium, copper and coated steel components are combined.

Suitable material combinations, isolation methods and surface treatment can reduce the risk.

UV Exposure

Outdoor non-metallic components, seals, labels and coatings can degrade under ultraviolet radiation.

Products intended for outdoor use should have appropriate UV resistance where prolonged sunlight exposure is expected.

Seals and Gaskets

Door gaskets are critical to maintaining enclosure ingress protection.

Gaskets can deteriorate because of:

• Age
• Heat
• Chemical exposure
• Compression damage
• UV exposure

They should be inspected as part of enclosure maintenance.

Maintenance of Industrial Enclosures

Even a correctly selected cabinet requires maintenance.

Useful checks can include:

• Door seals
• Locks and hinges
• Corrosion
• Water marks
• Condensation
• Fan operation
• Filter condition
• Air-conditioner operation
• Cable-gland sealing
• Bonding connections

Filter Maintenance

Clogged fan filters reduce airflow and can cause internal temperatures to rise gradually.

Maintenance intervals should reflect the amount of dust in the environment rather than using one interval for every installation.

Enclosure Temperature Monitoring

Temperature sensors or thermostats can provide early warning of cooling problems.

In network, telemetry and automation cabinets, temperature information can also be integrated into PLC or remote monitoring systems.

Remote Monitoring of Outdoor Cabinets

Unattended infrastructure can benefit from monitoring of:

• Internal temperature
• Door status
• Power failure
• UPS or battery status
• Humidity
• Network availability

This is particularly useful for telemetry, water infrastructure and remote industrial communication sites.

Battery Enclosures

Battery systems require enclosure consideration beyond ordinary electronics.

Battery chemistry, ventilation requirements, temperature, fault protection, weight and manufacturer instructions can all influence cabinet design.

Batteries should not simply be added to an existing sealed cabinet without checking these requirements.

PoE Equipment and Enclosure Heat

Industrial PoE switches can dissipate additional heat because they supply power to connected devices.

The switch's own consumption and PoE load should be included when assessing cabinet thermal conditions.

VSD Enclosures

Variable speed drives are significant heat sources and often require manufacturer-specified clearances.

Where multiple VSDs are installed in one enclosure, thermal management can become one of the main factors determining cabinet size and cooling requirements.

Outdoor VSD Panels

Outdoor VSD installations combine two difficult conditions: drive-generated heat and solar heating.

A sealed high-IP enclosure without an adequate thermal strategy can overheat even though it successfully keeps water and dust out.

Enclosures for Instrumentation

Instrumentation cabinets can contain signal isolators, transmitters, barriers, terminals and surge protection.

Low-level analogue signals can require careful segregation from power wiring and suitable EMC practices.

Enclosures for Fibre Optics

Fibre enclosures need suitable space for:

• Splice trays
• Patch panels
• Adapters
• Pigtails
• Service loops

Fibre bend radius and connector access should be protected during cabinet layout.

Enclosures for Wireless Equipment

Wireless installations can contain radios, routers, PoE equipment and surge protection.

Antenna cable routing and connector protection should be planned carefully.

A metal enclosure can attenuate radio signals, so internal antennas should not be assumed to work effectively through the cabinet.

Enclosures for Water and Wastewater Applications

Water infrastructure can expose cabinets to moisture, corrosive gases, outdoor weather and remote-site conditions.

Applications include:

• Pump control
• Reservoir monitoring
• Borehole control
• Telemetry
• Instrumentation

Material, condensation control, surge protection and remote monitoring are often important considerations.

Feeder Pillars and Outdoor Distribution Cabinets

Feeder pillars provide outdoor electrical distribution and can also incorporate control, metering or communication equipment.

Depending on the project, they can require:

• Robust weather protection
• Internal segregation
• Lockable access
• Cable termination space
• Metering
• Surge protection
• Remote monitoring

They should be engineered for the electrical duty and site environment.

Custom Fabricated Enclosures

Standard catalogue cabinets suit many applications, but some projects require custom fabrication.

Custom requirements can include:

• Non-standard dimensions
• Special door arrangements
• Internal partitions
• Sunshields
• Plinths
• Special gland plates
• Mounting frames
• Outdoor kiosks

Custom fabrication should still account for environmental protection, structural requirements and electrical design.

Common Enclosure Selection Mistakes

• Choosing a cabinet only by width, height and depth
• Assuming IP65 means suitable for every outdoor application
• Ignoring solar heat gain
• Ignoring condensation
• Using painted mild steel in an aggressive corrosive environment without assessing coating suitability
• Specifying stainless steel without considering the required grade
• Adding fans without considering the effect on ingress protection
• Ignoring component heat dissipation
• Not allowing space for cable bending and termination
• Forgetting door-mounted equipment depth
• Ignoring fibre bend radius
• Not specifying cable-entry direction
• Drilling holes without restoring corrosion protection or sealing
• Assuming an empty enclosure's IP rating automatically applies to the finished panel
• Confusing high IP rating with hazardous-area certification
• Ignoring future expansion and maintenance access

A Practical Planning Checklist

For an accurate enclosure quotation, provide as much of the following information as possible:

• Application: control panel, electrical distribution, networking, fibre, instrumentation, telemetry or other
• Indoor or outdoor: ___
• Required IP rating: ___
• Approximate width: ___ mm
• Approximate height: ___ mm
• Approximate depth: ___ mm
• Wall-mounted or floor-standing: ___
• Material: painted steel, stainless steel, aluminium, non-metallic or unsure
• Stainless grade if required: 304, 316 or project specification
• Environment: indoor clean, dusty, outdoor, coastal, washdown, wastewater, mining or other
• Ambient temperature: ___ °C
• Direct sunlight: yes/no
• Internal equipment: ___
• Estimated internal heat load if known: ___ W
• Cooling required: fan, air conditioner, heat exchanger, passive or to be determined
• Condensation control required: ___
• Mounting plate required: yes/no
• Plinth required: yes/no
• Sunshield or canopy required: yes/no
• Cable entry: top, bottom, side or unknown
• Gland plate required: yes/no
• Door-mounted HMI or controls: ___
• Viewing window required: yes/no
• Locking requirement: ___
• 19-inch rack mounting required: yes/no
• Required rack units: ___ U
• Custom fabrication required: yes/no/unsure
• Quantity: ___

For replacement enquiries, clear photographs of the existing cabinet, its nameplate, internal equipment and cable-entry arrangement can help identify a suitable replacement.

How This Fits Into the Wider System

A cabinet can bring together:

Electrical protection → 24 VDC power → PLC and I/O → industrial networking → instrumentation → VSDs or motor control → field cable termination

Other enclosures can be dedicated to fibre, networking, telemetry, outdoor electrical distribution or remote water infrastructure.

For a new enclosure requirement, dimensions, environment, IP rating, material, internal equipment, cable entry and cooling requirements are useful starting points. For replacements, the existing enclosure manufacturer, part number and clear photographs can help identify suitable options.

Technical Note

This article provides general industrial electrical and automation information. Enclosure selection, ingress protection, corrosion resistance, thermal management, electrical bonding, EMC, hazardous-area suitability, structural requirements and panel compliance must be assessed for the specific application. Manufacturer documentation, applicable standards, engineering specifications, site requirements and statutory requirements take precedence. Electrical and safety-related systems should be designed, fabricated, installed and verified by appropriately competent persons within the required scope.

Related catalogue examples: Network Cabinets & Racks. For an equipment enquiry, contact Softcore Group Industrial Solutions at info@softcoregroup.co.za.