Switchgear Panel Construction Types — Fixed, Cubicle, Compartmentalized & Draw-Out Explained

Not every switchgear panel is built the same way, and the construction type you choose has a direct effect on uptime, safety and how a fault in one feeder affects the rest of the installation. Here's how switchgear and controlgear assemblies are classified — from the simplest fixed-type switchboard to a fully draw-out compartmentalized panel — and where each one belongs.

Fixed-Type Construction

In a fixed-type assembly, every feeder is rigidly mounted and permanently wired to the main bus. It's the most cost-effective and by far the most common construction, and it suits the vast majority of general industrial and commercial installations well. The trade-off is that a fault on the bus side of one feeder can force a shutdown of the entire switchboard — acceptable for most facilities, but not for a process plant or critical load that can't tolerate downtime.

Cubicle-Type: Non-Compartmentalized vs Compartmentalized

A cubicle-type construction houses the feeders in a compact, sheet-metal enclosure with feeders stacked vertically to make efficient use of floor space — the standard form factor for most modern panels. Within this category, the key distinction is how much a fault in one feeder is allowed to spread:

• Non-compartmentalized type — all feeders share a single enclosure, so attending to one feeder means exposure to the others. Common in automation panels for drives, PLCs and UPS systems, control desks, junction boxes and distribution boxes.
• Compartmentalized type — each feeder is housed in its own separate compartment or module. A fault, particularly a short-circuit, stays contained to that one feeder instead of spreading to its neighbours. This is the construction behind drawout and non-drawout Motor Control Centres (MCC) and Power Control Centres (PCC).

PCC, MCC and DB — What's the Difference?

These three terms describe an assembly's position in the power distribution chain, not just its construction:

• PCC (Power Control Centre) — receives power from one or more sources and distributes it to downstream centres such as MCCs or DBs. Because it sits highest in the chain, its feeders carry the largest ratings.
• MCC (Motor Control Centre) — receives power from the PCC and feeds it out to individual load points, most of which are motors on a process line. Where a single process line is small enough, the PCC and MCC can be combined into one PMCC assembly to save space and cost.
• DB (Distribution Board) — a smaller assembly distributing power to end utilities such as lighting, HVAC, pump sets, firefighting systems and lifts, in an industrial, commercial or residential installation.

Draw-Out Construction: Semi vs Fully Draw-Out

In a draw-out assembly, every feeder sits on its own withdrawable chassis that can be racked out for maintenance or repair, and racked back in, without disturbing the incoming or outgoing power and control connections elsewhere in the panel. Identical modules can be swapped in minutes, which is why this construction is specified for installations that genuinely cannot tolerate downtime — refineries, fertilizer and petrochemical plants, power stations, hospitals and airports.

• Semi-draw-out type — the power contacts are draw-out, but the control terminals are plug-in and must be engaged or disengaged manually as the trolley is racked in or out. It works, but it's easy to get wrong: forgetting to disengage the control terminals before racking out can snap the wiring and turn a routine swap into a major repair.
• Fully draw-out type — both power and control contacts engage and disengage automatically as the trolley moves in or out of its module. This removes the human-error risk entirely and is the construction of choice for the most critical feeders.

Which Type Should You Choose?

For general indoor panels and control enclosures without a hard uptime requirement, a fixed or non-compartmentalized cubicle build is usually the right call — it's cost-effective and it's what the vast majority of installations actually need. Once a process can't afford an unplanned shutdown, or a fault in one feeder genuinely cannot be allowed to take down its neighbours, that's the point to move to a compartmentalized or draw-out design. See our guide to enclosure construction types for how the outer enclosure itself is built, and our IP ratings guide for the ingress protection these assemblies are tested to.