A good switchboard specification has one job, and one job only: remove ambiguity. It should define the board clearly enough that the project team, manufacturer, and buyer all understand what is being supplied, what technical basis it needs to meet, and what assumptions should not be left open.
Quick answer
A switchboard specification is a technical document that defines the electrical ratings, enclosure, internal form, outgoing circuits, compliance standards, and documentation requirements for a switchboard assembly. In New Zealand, the primary standard is AS/NZS 61439. A complete specification answers five questions: what the board is for, what electrical duty it must perform, what environmental conditions it faces, what compliance and construction standards apply, and what programme or delivery constraints exist.
In this article
When a specification is vague, important parts of the board scope get interpreted differently by different parties. That leads to inconsistent quotations, late design changes, scope gaps, programme delays, and commercial disputes that were avoidable at the start.
A stronger switchboard specification does not need unnecessary detail. It needs the right information in the right places. This guide sets out the 11 areas that matter, what often gets missed, and a checklist to run against any specification before it goes out for quotation.
For most projects, the specification becomes the foundation for both pricing and manufacturing. If it is too general, the quote will be based on assumptions. If it is clear, the board can be reviewed against a defined scope.
That helps with like-for-like comparison of quotations, better design coordination, fewer late changes, clearer responsibility boundaries, and a more reliable procurement process. In short, a good specification reduces uncertainty for everyone involved.
We review consultant-issued specifications and build to them every week from our Invercargill workshop, for projects across New Zealand. That includes industrial facilities and meat works in Auckland, commercial and light industrial boards in Hamilton and Tauranga, water and wastewater upgrades across Wellington and New Plymouth, dairy and food processing plants in Taranaki, Waikato, and Southland, and infrastructure work in regional centres nationwide. The same specification principles apply regardless of location or sector.
Before looking at the detail, a useful way to test any specification is to check whether it answers these five practical questions:
If any of those are unclear, the specification may look complete on paper while leaving real risk in the project.
These are the 11 areas a specification should cover for any commercial, industrial, or infrastructure project in New Zealand. Not every section applies to every job, but every section should at least be considered.
Start with the basic identifiers so the board is clearly tied to the job. This includes the project name, site location, drawing or document references, board designation or tag, revision status, and the responsible consultant or designer. It sounds administrative, but it matters. It ensures all parties are working from the same scope basis.
The specification should explain what the board is intended to do. Is it a main switchboard (MSB), distribution board, motor control centre (MCC), services or plant board, replacement in an existing installation, or a custom assembly for a specific application? The scope of supply should be defined as clearly as possible, including whether the board is new or replacement work, what equipment and functions are included, and what exclusions apply.
This is one of the most important parts of any specification. It should include the supply characteristics (voltage, phases, frequency, earthing arrangement per AS/NZS 3000), the main current rating, the incomer arrangement (MCCB, ACB, fused switch, isolator, direct busbar), busbar current rating, busbar bracing, and any system configuration information relevant to the board. A single line diagram (SLD) showing the supply source, main protection, metering position, and downstream distribution removes a great deal of ambiguity from this section. Without the electrical basis, the switchboard cannot be priced or designed with confidence. For projects still in the design phase, see our electrical consulting and design service.
The prospective short-circuit current at the point of installation should be stated clearly rather than assumed. If it is known or has been calculated, it should be included. This can materially affect switchgear selection, construction basis, and cost. If it is omitted, the quotation will rely on assumptions that may need revision later. For more on this, see what fault rating does a switchboard need.
For most projects, the outgoing schedule (sometimes called the schedule of equipment in tender documentation) is central to the whole board definition. It identifies circuit quantities, device types and ratings, feeder responsibilities, space and layout implications, protection coordination (including Type 2 coordination for motor circuits), and the actual functional scope of the board. A specification without a useful outgoing schedule is only partly complete. The schedule should also nominate spare capacity, whether expressed as spare ways or spare current capacity for future load growth.
If a particular form of segregation is required, it should be stated explicitly. The nominated form (Form 1, 2, 3a, 3b, 4a, 4b) can affect internal construction, compartmentalisation, board size, and pricing. It should not be left to inference or assumption. See what is form of segregation in a switchboard for a breakdown of each form.
The board should be specified for the environment it will actually face in service. Useful inputs include whether the location is indoor or outdoor, contamination conditions, washdown or moisture exposure, IP rating requirement, material or finish expectations, mounting arrangement, and any weather or durability considerations. This section is especially important for boards in plant areas, service yards, industrial spaces, or existing facilities with non-standard conditions.
Not every switchboard is simply a collection of protective devices. Some projects require revenue metering, sub-metering, power quality monitoring, control interfaces (PLC, relay logic, contactor control), variable speed drive (VSD) integration, interlocking, load-specific functions, or special operational arrangements. For projects with integrated control requirements, see automation and control. If these are not stated clearly they can be missed or under-allowed in the quotation.
This is one of the most commonly under-specified areas. Access limitations, space constraints, existing cable entry limitations, replacement sequencing issues, shutdown windows, lifting or transport constraints, and installation location realities are not secondary details. In upgrade and replacement work especially, they can be major drivers of design and cost.
A complete specification should explain what testing, compliance evidence, and project documentation are expected. Depending on the project that may include routine verification testing to AS/NZS 61439, Factory Acceptance Testing (FAT), Inspection Test Plans (ITP), compliance expectations, documentation deliverables (GA drawings, schematic drawings, as-built drawings), EPLAN or PowerCAD exports, labelling expectations (engraved circuit directories, traffolyte labels, duty labels), and project handover information. For ongoing service, switchboard maintenance and thermographic inspection should also be considered at specification stage. This gives the manufacturer a clear picture of what the final deliverables need to include, not just what the board itself needs to contain.
For a formal breakdown of the items that should be agreed between the specifier and the manufacturer under AS/NZS 61439, Standards New Zealand publishes a dedicated guidance document: SA/SNZ TR 61439.0:2016 Guide to Specifying Assemblies.
If delivery timing, shutdown windows, or staged installation matter, the specification should say so. Programme constraints can influence manufacturing planning, board format, staging strategy, and commercial response. A technically sound specification can still be incomplete if the timing expectations are not captured.
A switchboard specification should define the electrical, physical, environmental, and commercial basis clearly enough that the board can be priced and built with confidence. Anything less puts risk back into the project.
Even experienced project teams sometimes leave out details that later prove important. The most common omissions are:
These omissions are often the reason quotations come back with clarifications, exclusions, or scope assumptions that need to be worked through before a reliable comparison can be made.
Pre-issue checklist
Clive Wilson Switchboards supplies low voltage switchboards and motor control centres nationwide from our Invercargill workshop. Current and recent projects span from Auckland and Northland in the north, through Hamilton, Tauranga, Rotorua, New Plymouth, Napier-Hastings, Palmerston North, Wellington, Nelson, and Queenstown, to regional infrastructure across Southland and the West Coast.
The same specification principles in this guide apply regardless of location. Whether the board is bound for a dairy plant in Waikato, a meat works in Auckland, a water treatment upgrade in Wellington, an aluminium or metals processing facility in Southland, a commercial fit-out in Hamilton, or a renewable generation site in New Plymouth, a well-written specification is what produces consistent, comparable quotations.
We build on four proven platforms: Schneider Prisma Plus G (accredited builder), Simotrol, Logstrup, and Quantum. Platform selection is driven by your specification, fault level, IP requirement, footprint, and operational environment. Manufactured under our ISO 9001-certified quality management system, with assemblies designed and verified to AS/NZS 61439. Avetta registered and SiteSafe registered for procurement on major infrastructure projects nationwide. See our case studies for examples of recent work.
A switchboard specification should do more than describe the board in broad terms. It should define the electrical, physical, environmental, and commercial basis clearly enough that the board can be priced and built with confidence.
The best specifications reduce ambiguity early. That helps consultants, contractors, facility managers, procurement teams, and switchboard manufacturers all work from the same basis, with fewer surprises later in the project.
Where engraved circuit directories, identification plates, or duty labels are required as part of the switchboard build, these should be noted in the specification. See the CWS engraving service for available options.
A switchboard specification is a technical document that defines the requirements for a switchboard assembly, including its electrical ratings, form of construction, protection requirements, applicable standards, and functional scope. It gives the manufacturer a defined basis on which to price and build the board.
Without a clear specification, switchboard manufacturers must make assumptions when quoting. Different manufacturers may interpret the same project differently, leading to inconsistent quotes that cannot be compared fairly. A well-written specification removes ambiguity and gives every manufacturer the same technical basis to work from.
New Zealand switchboards must comply with AS/NZS 61439, which covers the design and verification of low voltage switchgear and controlgear assemblies. This standard replaced the older AS/NZS 3439 series and sets requirements for rated current, fault withstand, temperature rise, protection, and verification testing. Installation must also comply with AS/NZS 3000 (the Wiring Rules) and the Electricity (Safety) Regulations 2010.
The switchboard specification is typically prepared by the project electrical engineer or designer. For design-and-build projects the responsibility may shift partly to the switchboard manufacturer, but the project team must still define the operational and compliance requirements clearly.
The most common omissions include the required fault rating (PSCC), the form of internal segregation, the IP rating for the installation environment, the number and rating of outgoing circuits, and the applicable testing and verification standard. Missing any of these can result in assumptions that change the scope or cost of the board later.
A specification sets the technical, construction, and compliance basis for the whole board. A schedule (typically the outgoing feeder schedule) lists the circuits the board must serve, including device types, ratings, and destinations. The schedule forms part of the specification, not a replacement for it.
A reasonable starting point for most commercial and industrial boards is 20% spare capacity, expressed either as spare ways or spare current capacity. The actual figure should reflect the expected load growth, the cost of future modification, and the physical space available. For critical infrastructure, higher spare allowances are common.
Reviewed by Chris Wilson, Co-Director, Clive Wilson Switchboards. Registered electrician, 15+ years in LV switchboards. Updated April 2026.
