Purpose

Decide whether supplementary protective bonding is required from the protective measures and measured conditions, not from room name alone.

Learning objectives

• Define supplementary bonding
• Distinguish it from main bonding
• Recognise conditions for omission
• Use measured evidence and current rules

Supplementary bonding locally connects simultaneously accessible conductive parts when needed to reduce touch voltage. Modern RCD and ADS arrangements can change whether it is required, but omission must be justified.

Core theory

Supplementary bonding connects relevant exposed-conductive-parts and extraneous-conductive-parts within a location; it does not replace the installation earthing conductor or main bonding.

For locations such as bathrooms, current requirements may permit omission only when specified conditions for ADS, RCD protection, and effective main protective bonding are satisfied.

Continuity and resistance evidence, actual accessibility, equipment class, circuit protection, and the current edition determine the result; a historic rule of bonding every pipe is unsafe oversimplification.

Assumptions: No inspection or measurements supplied.

1. Conditions: RCD presence and main bonding are relevant but not the complete evidence set.
2. Verify: Confirm ADS, protective-conductor continuity, relevant parts, and every current regulatory condition.
3. Record: Only a competent assessment can justify omission.

No; all current omission conditions and measured evidence must be verified.

Reasonableness check: One protective measure does not prove the performance of the others.

Knowledge check

Answer: No. They address different scopes and both depend on the protective design.

Practical exercise

Create an evidence checklist for a bathroom supplementary-bonding assessment without declaring a site compliant.

Summary

• Supplementary bonding is local
• Omission is conditional
• Measured evidence and current rules decide