---
title: "Switchroom Sizing Calculator: Main Switchboard Room Layout, Clearances and Exits to AS/NZS 3000"
url: "https://scaleset.com.au/calculator/switchroom-sizing"
description: "Free switchroom sizing calculator: drag boards, inverters and battery cabinets onto a plan and read the minimum room, AS/NZS 3000 clearances, exits and doorway."
updated: "2026-09-25"
standards:
  - "AS/NZS 3000:2018 (Wiring Rules: Clause 2.10.2.2 switchboard accessibility and emergency exit facilities, Figures 2.19 to 2.24)"
  - "AS/NZS 5139:2019 (Battery systems: the working space and exit clearances for a battery energy storage cabinet)"
  - "AS/NZS 61439 (Low-voltage switchgear and controlgear assemblies: the switchboard the room is sized around)"
author: "Wisam Tozah (B.Eng (Electrical), MIEAust, CPEng, NER, NSW DBP, NSW PRE, APEC, IntPE(Aus))"
site: "ScaleSet"
license: "https://scaleset.com.au/terms"
usage: "Cite and link. Do not reproduce or train on this content."
---

# Switchroom Sizing Calculator: Main Switchboard Room Layout, Clearances and Exits to AS/NZS 3000

Source: https://scaleset.com.au/calculator/switchroom-sizing

Free, browser-based switchroom sizing calculator for Australian and New Zealand electrical engineers: lay the main switchboard room out on a plan and read the room it needs. Drag a main switchboard, a board (a distribution board, a general board, a metering panel or a board by others), a power factor correction bank, a UPS, a solar inverter, a battery energy storage cabinet or a comms rack from the library onto the plan, and the calculator draws the working space AS/NZS 3000:2018 Clause 2.10.2.2 asks for around each one: 1.0 m in front of every face that needs access (0.6 m in a domestic installation) and an unimpeded 0.6 m beyond an open door. Two boards that face each other share one aisle, 1.0 m face to face and 0.6 m between their open doors, never doubled. A switchboard takes its size from its main rating through the same engine as the Switchboard Sizing calculator, and every dimension stays editable. As a board is dragged the gap in front of it is dimensioned live, and it snaps onto the exact figure the rule asks for. The room is the minimum that holds the layout and its clearances, reported as the internal width and length, the area and the clear height, with the working of each dimension written under the figure; type a width or a length over it and the layout is checked against your own room instead. The exits are judged against Clause 2.10.2.2.2: a board of 800 A or more, or longer than 3 m, needs two exit paths spaced well apart unless 3 m is clear in front of it, and every doorway is at least 900 mm wide and 2000 mm high, 2200 mm recommended for a prefabricated board, opening outward. The report is a PDF with the plan, the equipment schedule and every finding with its clause, and a DXF that opens at true size in CAD. It is a layout for design development and a room brief, not a construction drawing.

The ScaleSet Switchroom Sizing Calculator lays out the equipment inside a main switchboard room on a plan and sizes or checks the room against the access, exit and doorway rules of AS/NZS 3000:2018 Clause 2.10.2.2. It is not the Switchboard Sizing calculator, which gives one switchboard its own width, height, depth and bays, and it is not the BESS Sizing calculator, which plans a battery installation on its own: this tool takes the boards, cabinets and inverters those tools size and finds the room that holds them all. It is a free browser-based layout tool for design development and does not replace the manufacturer's dimensions, the delivery route or the building code.

## Key facts

- 1.0 m clear in front of every face of a closed switchboard that needs access (0.6 m in a domestic installation), from AS/NZS 3000 Clause 2.10.2.2.1(b)(i).
- An unimpeded 0.6 m beyond an open switchboard door (Clause 2.10.2.2.1(b)(ii)), so the space in front is the larger of 1.0 m and the door leaf plus 0.6 m.
- Two switchboards facing each other share one aisle: 1.0 m face to face and 0.6 m between their open doors (Figure 2.23). The metre is never doubled.
- A switchboard rated at 800 A or more per phase, or longer than 3.0 m, puts the room under Clause 2.10.2.2.2: two emergency exit paths spaced well apart, unless 3.0 m is clear beyond the board's open doors (Figure 2.24).
- In that room every doorway is at least 900 mm wide and 2000 mm high, 2200 mm recommended for a prefabricated switchboard, unless the board replaces an existing one in the same location; the door opens in the direction of egress without a key or tool from inside.
- A switchboard on the plan is sized from its main rating by the Switchboard Sizing engine; a typed width, depth or height holds until the rating size is asked for again.
- A battery energy storage cabinet keeps the AS/NZS 5139 figures: 900 mm on its working side, 300 mm at an end, 100 mm behind and 600 mm clear of an exit.

## Who this page is for

Electrical engineers, electrical designers, switchboard builders, architects and building services coordinators who need the size of a main switchboard room, a switchroom or an electrical plant room early in design, and electricians checking that an existing switchroom meets the AS/NZS 3000 access and exit rules.

## Relevant standards

- AS/NZS 3000:2018 (Wiring Rules: Clause 2.10.2.2 switchboard accessibility and emergency exit facilities, Figures 2.19 to 2.24)
- AS/NZS 5139:2019 (Battery systems: the working space and exit clearances for a battery energy storage cabinet)
- AS/NZS 61439 (Low-voltage switchgear and controlgear assemblies: the switchboard the room is sized around)

## What this tool does

- Drag a main switchboard, distribution boards, metering, a board by others, PFC, UPS, solar inverter, BESS cabinet and comms rack onto a plan, drawn with the EleCAD symbol library.
- Every item carries the 1.0 m working space of AS/NZS 3000 Clause 2.10.2.2.1 in front of each accessed face, and the 0.6 m beyond an open door, drawn as a tint with the rule written on it.
- Boards that face each other share one aisle: 1.0 m face to face and 0.6 m between the open doors, the way Figure 2.23 draws it, never doubled.
- A switchboard is sized from its main rating by the Switchboard Sizing engine; type a width, depth or height to override it.
- The room is the minimum that holds the layout, with its working written under the figure; type a width or a length over it and the layout is checked against your own room.
- Drag a board and the gap in front of it is dimensioned as it moves, red with the figure it needs when short; it snaps onto the exact clearance the rule asks for.
- The exits follow Clause 2.10.2.2.2: two exit paths for a board of 800 A or more or over 3 m long, unless 3 m is clear in front of it; doorways 900 wide and 2000 high, 2200 recommended.
- A clearance that is not met turns red and hatched and says by how much; every finding names its clause and selects the item it is about.
- A section beside the clear height draws the tallest item, the 600 mm above it and the tallest door.
- A PDF report with the plan, the equipment schedule and the findings, and a DXF that opens at true size in CAD.

## How to lay out a switchroom

1. **Put the equipment on the plan** — Drag a main switchboard from the library onto the plan, then the boards (each one a DB, a general board, a metering panel or a board by others, set on its panel), the PFC bank, the UPS, the inverter, the battery cabinet or the comms rack the room holds. A room door is a single leaf, two leaves, a leaf and a half, a sliding panel or a roller shutter. On a phone, tap a chip and it lands where there is room.
2. **Set each item** — Select an item and type its rating: a board takes the size the Switchboard Sizing engine gives it. Type a width, depth or height to override it. Set which wall the front faces, whether the rear or the ends need access, and the door leaf.
3. **Arrange the room** — Drag items into place; they snap to the walls, to each other and to the exact clearance the rule asks for. Press R to turn one. Boards that face each other share one aisle. A zone that fails turns red and says by how much.
4. **Place the doors** — Drop a room door on a wall and slide it along. A door opens outward. A board of 800 A or more, or longer than 3 m, needs two exits spaced well apart or 3 m clear beyond its open doors.
5. **Read the room** — The room is the minimum internal width and length that holds the layout, with the area and the clear height, and the working of each dimension under the figure. Type a width or a length over it to check the layout against your own room. The findings list names every clearance, exit and doorway rule the layout misses, with its clause.
6. **Take the report** — Export in the toolbar produces the PDF with the plan, the equipment schedule and the findings; DXF opens the plan at true size in CAD. The address bar is the link to the layout.

## Switchroom layout to AS/NZS 3000: the clearances, the exits and the doorway

### What the tool actually does

It draws a plan of the switchroom and keeps it honest. Each piece of equipment is a box at its real size, and round each box the tool draws the working space the standard asks for, with the rule written on it. Move a board and the zones move with it, and the gap in front of it is dimensioned as it moves; move it too close to a wall or to another board and the zone turns red and hatched and says by how much. The room is either sized to the layout or checked against the size you type, and the exits and the doorway are judged with it.

Nothing on the plan is typed twice. A switchboard takes its width, depth and height from its main rating through the Switchboard Sizing engine, so a 1600 A main switchboard on the plan is the board that page would draw. A general board and a board by others are sized the same way; a metering panel, a PFC bank, a UPS, an inverter and a comms rack take the cabinet band typical of their rating, and a battery cabinet is one rack per 100 kWh. Any dimension can be typed over, and one click puts the rating size back.

### The working space round a switchboard

Clause 2.10.2.2.1 asks for two things. A 1.0 m minimum distance from all faces of a closed switchboard that need to be accessed, which a domestic installation may reduce to 0.6 m. And an unimpeded space of at least 0.6 m round the switchboard with the switchgear doors in any position. The second rule is what decides most rooms: a board with an 800 mm hinged door needs 1.4 m in front of it, not 1.0 m.

Figures 2.19 to 2.21 draw the cases: a freestanding board, a board in a corner, a board with one end against a wall. A door swung 180 degrees past the end of a board needs 0.6 m beyond it, so an end that needs access takes the door leaf plus 0.6 m. An end that does not need access can stand against the wall.

### Facing switchboards share one aisle

Figure 2.23 is the one most often misread. Two boards facing each other do not each need their own metre. They share one aisle, at least 1.0 m face to face and at least 0.6 m between their open doors. Two boards with 600 mm doors need an 1800 mm aisle; two dead-front boards with no doors need 1000 mm. The tool pairs boards that face each other across a gap smaller than their two working spaces, draws the one aisle between them, and dimensions it.

A room doorway keeps 0.6 m from the switchboard doors (Figure 2.22), whichever way the room door is hung: the board's own doors swing into the room either way. The case most often missed is a board whose end stands against a wall. The outer leaf of a line-up hangs on the outer jamb, so opened it lies flat along that wall, and a doorway cut through the same wall is the one it closes off. A switchboard door that opens into a passage must also be securable in the open position so a worker is not pushed towards the board.

### The room, the exits and the doorway

Clause 2.10.2.2.2 applies to a switchboard room once the switchboard is rated at 800 A or greater per phase, or is more than 3.0 m long. Such a room has at least two emergency exit paths spaced well apart, unless a clear space of at least 3.0 m is provided in front of the switchboard and its equipment with the doors in every position, in which case one exit will do (Figure 2.24). Doors open in the direction of egress without a key or tool from the switchboard side. Openings are not less than 2.0 m high and 0.9 m wide, and the standard recommends 2.2 m so a prefabricated board can be brought in.

The main switchboard is readily accessible and within easy access of an entrance to the building (Clause 2.10.2.3), never inside a tenancy of a multiple installation, and the door of its room is marked to say so (Clause 2.10.2.4). The room is well ventilated, protected from moisture and has space to replace individual items (Clause 2.10.2.1). Those are notes on the report rather than findings on the plan; the plan checks what geometry can check.

### What the room figure means

Sized for the layout, the room is the smallest rectangle that holds every item and its working space, rounded up to 50 mm, with the working of each dimension written under the figure (MSB 600 + the aisle 1 400 + DB-1 450 = 2 450 deep) and the clear height taken as the tallest item plus 600 mm unless you enter one. It is the room to ask the architect for. Type a width or a length over it, or drag a wall on the plan, and the room is yours and the plan is checked against it: anything outside the room, or short of a wall, becomes a finding. Size it for me hands the room back to the layout, and neither way moves the equipment.

The result is indicative. The manufacturer's dimensions, the delivery route, ventilation, fire separation and the building code all apply before the room is built, and the report says so. What the tool guarantees is that the room it reports meets Clause 2.10.2.2 for the equipment on the plan, and that every shortfall is shown where it is.

## Key terms

- **Switchroom** — A room or enclosed space housing a switchboard, which a person has to enter to reach it. Clause 2.10.2.2.2 applies to it once the board is 800 A or more or longer than 3 m.
- **Face** — A side of a switchboard a person works from: the front always, the rear where the board is rear-connected, the ends where end access is needed. Each accessed face carries 1.0 m of working space.
- **Unimpeded space** — The 0.6 m that must stay clear with switchgear doors in any position, so a person is never trapped against an open door.
- **Shared aisle** — The one working space between two switchboards that face each other: at least 1.0 m face to face and 0.6 m between their open doors, as Figure 2.23 draws it.
- **Emergency exit path** — A way out of the switchroom a person can take in an arcing fault. A room under Clause 2.10.2.2.2 has two, spaced well apart, unless 3.0 m is clear beyond the board's open doors.
- **Direction of egress** — Out of the room. A switchroom door opens that way and is operable from inside without a key or tool.
- **Prefabricated switchboard** — A board delivered assembled, in bays, and carried into the room on its side or upright; the reason a 2.2 m doorway is recommended and the tool checks the deepest board against the widest door.
- **Domestic installation** — An installation in a domestic premises, where the 1.0 m in front of a switchboard may be reduced to 0.6 m and the room-door rules need not apply.
- **MSSB** — A mechanical services switchboard: a distribution board feeding plant, laid out on the plan as a distribution board.

## Frequently asked questions

### How much clear space does a switchboard need in front of it?

AS/NZS 3000:2018 Clause 2.10.2.2.1 asks for 1.0 m from every face of a closed switchboard that needs to be accessed, 0.6 m in a domestic installation, and an unimpeded 0.6 m with the switchgear doors in any position. So the space in front is the larger of 1.0 m and the door leaf plus 0.6 m: a board with an 800 mm door needs 1.4 m. The calculator draws that zone on the plan for every item.

### Do two facing switchboards need 1 m each, making a 2 m aisle?

No. Figure 2.23 of AS/NZS 3000 shows facing switchboards sharing one aisle: at least 1.0 m face to face and at least 0.6 m between the open doors. Two boards with 600 mm doors need an 1800 mm aisle, and two boards with no doors need 1000 mm. The calculator pairs facing boards automatically and dimensions the aisle they share.

### When does a switchroom need two exits?

Clause 2.10.2.2.2 requires at least two emergency exit paths, spaced well apart, from a switchboard room where the switchboard is rated at 800 A or more per phase or is longer than 3.0 m. The exception in Figure 2.24 allows one exit where a clear space of at least 3.0 m is provided in front of the switchboard and its equipment with the doors open. The calculator counts the doors on the plan against that rule.

### How big must a switchroom door be?

Clause 2.10.2.2.2(b): an unobstructed opening of not less than 2.0 m high and 0.9 m wide, and the standard notes that 2.2 m or higher is recommended so a prefabricated switchboard can be brought in. The door opens in the direction of egress without a key or tool from the switchboard side.

### Where do the equipment sizes come from?

A switchboard is sized by the Switchboard Sizing engine from its main rating: the bays it needs, the depth band for the rating and a 2200 mm height, with an ACB board racking out 600 mm. The other equipment takes the cabinet band typical of its rating, and a battery cabinet is one 600 x 1000 x 2200 rack per 100 kWh. Type a width, depth or height and it holds; one click puts the rating size back.

### What clearances does a battery cabinet get?

The AS/NZS 5139 figures the BESS Sizing calculator already applies: 900 mm unimpeded on the working side with the door swing inside it, 300 mm at an end, 100 mm behind, and 600 mm clear of an exit. A battery cabinet facing a switchboard shares an aisle at the larger of the two rules.

### Is this the same as the Switchboard Sizing calculator?

No. Switchboard Sizing gives one board its own width, height, depth and bays from its functional sections. Switchroom Sizing takes those boards and the other equipment in the room, lays them out on a plan, and finds the room that holds them with their clearances, exits and doorway. The two are meant to be used together.

### Does the 1.0 m apply to a distribution board on a wall in a corridor?

Yes. Clause 2.10.2.2.1 applies to every switchboard, and the 1.0 m is measured from the face of the closed board into the corridor. What changes in a corridor is the door: a switchboard door that opens into a passageway must be securable in the open position (Clause 2.10.2.2.3), and the tool draws the line the open door reaches.

### Why does the room grow when I add a door?

It does not, unless the door is on a wall the layout has already filled. In a room sized for the layout the walls hug the equipment and its working space; a door sits in a wall and the tool checks that nothing stands within 1.0 m inside it. Add the door first and the equipment settles round it.

### Why is the aisle between my two boards 1800 mm and not 1000 mm?

Because the doors open into it. Figure 2.23 asks for 1.0 m face to face and 0.6 m between the open doors; with 600 mm leaves on both boards the doors reach 1200 mm across the aisle, and 600 mm past them is 1800 mm. Reduce the door leaf or turn one board and the aisle shrinks with it.

### What is the minimum size of a switchroom?

AS/NZS 3000 sets no room size. A switchroom is as big as the equipment in it plus the working space round each face: 1.0 m in front of every face that needs access, 0.6 m beyond an open door, one shared aisle between boards that face each other, and, for a board of 800 A or more or longer than 3 m, two exits spaced well apart. The calculator finds that room for a layout: a 1600 A main switchboard with a 200 kVAr PFC bank beside it and two distribution boards facing them needs 4.6 m by 2.45 m internal, 11.3 m², with a 1.4 m aisle between the boards.

### What clear height does a switchroom need?

Clause 2.10.2.2 gives no ceiling height. The calculator allows the tallest item plus 600 mm for the top cable entries and for lifting a bay into place, and draws it in a section beside the figure: the tallest item, the 600 mm above it, the ceiling and the tallest door. Type a clear height and it replaces the allowance; the finding that a door is lower than the tallest board stays.

### Can I type my own room size?

Yes. The width and length fields hold the minimum the layout needs; type a figure over either one and the room becomes yours at that size, the layout is checked against it, and anything outside the walls or short of one becomes a finding. Size it for me hands the room back to the layout. Dragging a wall on the plan does the same.

### Can I use this for an existing switchroom?

Yes. Type the internal width and length over the minimum, place the equipment where it stands and the doors where they are, and read the findings. Each one names the shortfall in millimetres and the clause behind it.

## Related ScaleSet pages

- [Switchboard Sizing Calculator](https://scaleset.com.au/calculator/switchboard-sizing)
- [BESS Sizing (battery energy storage)](https://scaleset.com.au/calculator/bess-sizing)
- [Arc Flash Calculator](https://scaleset.com.au/calculator/arc-flash)
- [Maximum Demand Calculator](https://scaleset.com.au/calculator/max-demand)
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- [Generator Sizing Calculator](https://scaleset.com.au/calculator/generator-sizing)
- [EleCAD Single Line Diagram Builder](https://scaleset.com.au/elecad)
- [Design Guides](https://scaleset.com.au/design-guide)
- [Calculation Verification](https://scaleset.com.au/verification)

## About this page

Written and reviewed by Wisam Tozah, Associate Electrical Engineer (B.Eng (Electrical), MIEAust, CPEng, NER, NSW DBP, NSW PRE, APEC, IntPE(Aus)), Sydney, Australia. How the calculations are tested and reviewed: https://scaleset.com.au/verification. Profile: https://scaleset.com.au/creator.

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