Consumer Unit Configurator

Size the board, main switch and protection strategy, and generate a circuit schedule to BS 7671.

Consumer Unit Configurator

Size the board, main switch and protection strategy and generate a circuit schedule to BS 7671 (Amendment 2).

Circuits (quantity of each)

Required for most domestic (Amd 2)

Configuring a consumer unit

Board size is the sum of active circuits, spare ways and a way for the Type 2 SPD that Amendment 2 now expects on most domestic installations — rounded up to a standard size. The protection strategy then determines how circuits are grouped: a full-RCBOboard gives every circuit its own protection, while a cheaper dual-RCD board groups circuits under two RCDs.

The configurator also estimates the diversified demand to size the main switch and lays out a circuit schedule you can use as a starting point.

Frequently Asked Questions

Free: BS 7671 Quick Reference Card

Max Zs values, diversity factors, cable ratings, voltage drop — one printable page. Plus occasional emails with calculator updates and useful tips.