Form 2 is where the busbars are isolated from the functional units. Functional units refer to devices such as circuit breakers, contactors, and other circuit control or protection devices. We isolate the busbars so that there is less chance of a person accidentally touching live busbar sections when working on a functional unit.

But one thing to mention is that in Form 2, the functional units themselves aren’t isolated from one another. If you open a panel, you’ll still have all the functional devices in clusters. The separation is only between the busbars and the set of functional units.

Form 2a vs. Form 2b – What’s the Difference?

Form 2 is divided into two subforms—Form 2a and Form 2b—both providing somewhat varying protection.

Form 2a

In Form 2a, the busbars are isolated from the functional elements, but not the terminals for external conductors from the busbars. So when you’re connecting or removing cables, you can still be working close to the busbars. It’s better than Form 1 but not safest if you consider live maintenance conditions.

Form 2b

Form 2b goes one step further. Here, not only are busbars isolated from the functional parts, but terminals for external cable connections are also isolated from the busbars. This is usually achieved with barriers, partitions, or insulation. Form 2b is utilized in most contemporary installations since it provides a safer working environment, especially when the switchboard must remain live when being serviced.

There are also sub-forms within Form 2b:

Type 1 employs insulation (such as PVC sleeves or coating) to physically separate the busbars.

Type 2 employs solid barriers or metallic/non-metallic partitions for an enhanced physical separation.

Why Use Form 2?

Form 2 switchgear is commonly found in commercial high-rise buildings, industrial complexes, and infrastructure developments. Form 2 gives an acceptable compromise between safety, economy, and accommodation. Not all installations need the full segregation available with Form 3 or 4. In most applications, the added protection from separating the busbars from the functional units is sufficient to address safety concerns and satisfy regulatory requirements.

Practical Advantages of Form 2

Enhanced Operator Safety

By isolating busbars, we minimize the hazard of contacting live equipment when doing maintenance. This allows technicians to perform maintenance on functional equipment with greater assurance.

Cost Savings

Form 2 is cheaper to construct than higher levels of segregation. It has fewer partitions and less custom fabrication required but still fulfills most of the safety needs.

Space-Efficient Design

Since the functional units are not separately compartmentalised, Form 2 panels are generally smaller than Form 3 or 4 switchboards. This suits them for use in installations where space is at a premium.

Easier Cable Management

Because the terminals are mounted together (particularly in Form 2a), cable terminations may be simple. Although this can be regarded as a disadvantage from a safety point of view, it tends to accelerate installation and save money.

Advantages of Form 2

Of course, no system is perfect. Form 2 doesn’t provide the same level of operational safety as Forms 3 and 4, especially if multiple circuits are being maintained at once. Since functional units aren’t separated, there’s still a chance of coming into contact with live components from other circuits while working on one. This is why many large-scale industrial or critical infrastructure projects prefer Form 3 or 4 switchboards, despite the higher cost.

Where You’ll Find Form 2 Switchgear

Form 2 configurations are common in:

Commercial buildings, such as shopping centres or office towers.

Manufacturing plants, where cost and space constraints make it a practical choice.

Infrastructure projects, like smaller substations or public utilities, where moderate safety and reliability requirements are balanced with budget considerations.

Standards and Compliance

LV switchgear and controlgear assemblies tend to comply with AS/NZS 61439, which is very similar to IEC 61439. The types of internal separation (including Type 2) are covered within this standard. What precise type a given project needs is typically decided by the design engineer or final customer, depending on considerations such as maintenance routines, operational safety, and potential future expandability.

Selecting Between Form 2a and 2b

If choosing between Form 2a and Form 2b, the decision usually boils down to priorities of safety concerns and costs. Form 2b provides an increased degree of protection since the cable terminals are isolated from the busbars, minimizing chances of contact mistakes while working on cables. For most switchboard installations today, Form 2b is the minimum recommended, particularly for commercial and industrial use where live working might be needed.