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Maintenance and

Approved Contractor


Many existing electrical installations require one or more additions or alterations during their lifetime.
An addition or alteration may be minor (such as the addition of a point to a final circuit, or the repositioning of a point) or major (such as the addition of new final circuits, distribution circuits, distribution boards and an upgrade to the supply).

Where an addition or alteration (whether temporary or permanent) is to be made to an installation, the relevant requirements of BS 7671 have to be met such that both the addition or alteration is safe, and the safety of the existing installation is not impaired.

This section includes details on the following:

  1. Introduction

  2. Assessment of an existing installation

  3. Existing equipment which may have to carry increased load

  4. Existing earthing and bonding arrangements

  5. Additional considerations

  6. Upgrading of an existing installation, where necessary

  7. Design and construction of the addition or alteration

  8. Inspection and testing

  9. Certification
Please download the full PDF here