Control Panel Enclosure Fabrication: PLC Cabinets and Automation Enclosures

A control panel enclosure is judged on the day it is commissioned, not on the day it is delivered. If the mounting plate is in the wrong place, the cable entries do not line up with the ducts, or the door does not compress its gasket, those problems surface in the plant rather than in the workshop. This guide covers the fabrication decisions that decide whether commissioning is straightforward.

What a Control Panel Enclosure Has to Do

The enclosure is the frame that everything else in the panel is assembled onto, and mistakes in it are paid for by the electrician.

Formats: Wall-Mount, Floor-Standing and Modular

• Wall-mounted enclosures suit small panels and remote installations; the load path runs into the wall, so the mounting bracket and the wall type matter.
• Floor-standing single-door cabinets are the general-purpose choice; depth and door width follow the internal layout.
• Double-door cabinets allow a wide panel without an impractically heavy door; the second leaf needs a defined closing sequence.
• Modular and bayable systems allow extension, with a shared side panel and often a shared busbar and mounting plate.
• Console and desk enclosures combine an operator interface with a control section and need their own ergonomic design.

Frame Construction and Dimensional Discipline

• Keep the mounting plate dimensions, the fixing pattern and the internal depth under control, because they set where every device lands.
• Use a consistent datum, usually the inside face of a side panel or the mounting plate surface, and reference all internal features from it.
• Reinforce the base where the cabinet will be lifted or skidded, and provide lifting points.
• Make side and rear panels removable where the site requires it.
• Where cabinets will be bayed, use a side profile designed for it rather than drilling holes in a flat panel.

Mounting Plates, DIN Rails and Internal Layout

• Provide a standard perforated mounting plate unless the internal layout is fixed, in which case a drilled plate may be more convenient.
• Give the plate a defined position and a repeatable fixing pattern so that pre-assembled sub-panels can be built off-line.
• Allow for DIN rail positions and for the depth of devices mounted on them.
• Leave space for wireways and for the bend radius of the wiring, not just for the devices.
• Where a device has a defined mounting height, such as an operator display, put that height on the drawing.

Gland Plates, Cable Entries and Busbar Openings

• Use removable gland plates in the base, and in the roof where cables enter from above.
• Size the plate for the expected cable count with room for later additions, and provide spare plugged entries.
• Keep power and signal entries separated, with physical barriers where the specification requires it.
• Provide a defined aperture for a busbar trunking entry where cabinets are bayed.
• Protect the entry with a grommet, a brush strip or a gland plate seal so the protection class is not lost at the entry.

Doors, Latching and Protection

• Use multi-point latching on tall doors so the gasket compresses evenly.
• Make the hinge side and the door swing suit the plant layout, and allow the door to be reversed where possible.
• Provide a door stop or a hold-open feature where the door is heavy.
• Design the door-mounted device interface so that devices can be fitted without stressing the door.
• Provide a door earthing bond where the door carries electrical devices.

Thermal Provisions Built into the Enclosure

• Provide a defined aperture and mounting face for the selected cooling device.
• Keep the aperture away from the top of the door where it would fight the natural convection path.
• Provide space for a thermostat, a filter and a shroud if a filter fan is used.
• Where a filter fan is fitted, allow for a matching filtered exit so the air has somewhere to go.
• Consider the internal temperature at the top of the panel, which is where the hottest devices usually sit.

Protection Class and Where It Is Lost

The protection class is usually lost at the details rather than at the door.

• Entries: glands sized and fitted correctly, and gland plates sealed.
• Gaskets: continuous, correctly compressed and not damaged by a latch or a hinge.
• Locks and hinges: each one is a potential path if it interrupts the gasket line.
• Joins between cabinets: a bayed pair has two gaskets and a seal between them.
• Roof apertures: a filter or a fan shroud must seal as well as the panel it replaces.

Finish, Labels and Documentation

• Powder coating is the default, with masked earth and mounting faces.
• Galvanised or stainless where corrosion resistance is the priority.
• Labels for the panel identification, the voltage and the warning notices, applied after coating.
• Documentation including a dimensional record of the mounting plate and the gland plate, and the as-built layout where the project requires it.

First-Article Checks

Our Approach to Control Panel Enclosures

• We fabricate wall-mount, floor-standing and modular enclosures, doors, mounting plates, gland plates, plinths, internal barriers and cooling apertures.
• We dimension the internal features from a single datum and cut the entries to the buyer's cable schedule rather than to a house pattern.
• We will tell you when a requested internal layout will not fit the enclosure depth once the wiring space and the cooling device are allowed for.
• We do not supply the electrical devices, the wiring, the cooling units or the protection relays, and we do not certify the electrical design or the panel's compliance with any electrical standard.
• Every quotation states which operations are completed in our plant.

Send the internal layout, the cable schedule and the environment, and the enclosure can be built so that commissioning is an assembly job rather than a correction.

Frequently Asked Questions