chalkline. Snap the line. Build to it.
glossary Glossary 3 min read

Switchboard

A domestic switchboard houses the main switch, RCDs, MCBs, surge protection, and circuit labels. Renewal triggers AS/NZS 3000 upgrade work. Builder primer.

By Chalkline. Last updated 14 May 2026. Verified 14 May 2026.

Ask Chalkline about this →

A switchboard is the wall-mounted enclosure that houses every protective and control device on the customer side of the meter. On a residential build it contains the main switch, the residual current devices (RCDs) protecting each circuit family, the miniature circuit breakers (MCBs) protecting each circuit, neutral and earth bars, surge protection if specified, and the circuit labelling.

Two configurations on residential builds:

  1. Single domestic switchboard. One enclosure handles all distribution. Standard on single-storey and most two-storey houses up to about 250 m².
  2. Main + sub configuration. A main switchboard near the meter feeds one or more sub-boards in the body of the house. Used on larger homes, additions, three-phase installations, or where the distance from meter to load centres makes single-board uneconomic. Each sub-board has its own main switch.

What sits inside (typical residential):

  • Main switch (rated to the consumer mains; commonly 80 A or 100 A single phase).
  • RCDs for socket-outlet, lighting, and dedicated-circuit groups (Type A or Type II RCDs to AS/NZS 3000). RCD protection is required on every final sub-circuit under the current Wiring Rules.
  • MCBs sized to the cable and load: 10 A for lighting, 16 A or 20 A for general power outlets, 25 A or 32 A for dedicated circuits (oven, hot water, EV charger, ducted air-con).
  • Surge protection device (SPD) at the main switchboard, increasingly common on new builds and required by some supply authority Service and Installation Rules.
  • Circuit labelling: legible labels matching the as-built electrical drawings. The certifier checks this at OC.
  • Spare ways: minimum 25% spare capacity (in MCB ways) for future circuits is a common contract requirement.

Renovation trigger. The most common reason to upgrade a switchboard during a renovation is adding circuits the existing board cannot accommodate (ducted air-con, solar inverter, EV charger, electric hot water swap, additional outlets in a kitchen reno). The other trigger is old ceramic fuse switchboards that no longer comply with current AS/NZS 3000 RCD requirements; any major work on such a board typically requires a full upgrade.

For builders.

  1. Identify the upgrade need at quote stage. Discovering mid-fit-out that the existing board cannot take the new circuits adds $1,500 to $4,000 ex-GST plus the network connection downtime.
  2. Switchboard work is licensed-electrician only. Builders touching a switchboard (even removing a cover plate) is an offence under state electrical safety regulations.
  3. OC inspection check. The certifier reads the labels, checks the main-switch and RCD signage, and tests RCD operation. Disorganised labelling or missing RCDs are common reasons for OC delay.

Also known as: meter box (informal), electrical panel, consumer unit, fuse board.

Category: Compliance / electrical / fit-out.

See also

Last updated: 2026-05-14. Verified: 2026-05-14.

Related articles