Renovation or new installation: which rules apply

It is the question that comes up on renovation jobs: does the whole house have to be brought up to current standards, or only what you touch? The answer shapes the quote, the schedule and the inspection. Book 1 of the RGIE gives clear reference points: the notion of significant modification, an inspection limited to the added or modified part, and specific provisions for existing installations.

The general principle

Under subsection 1.4.1.4 of Book 1, repairs, additions and modifications to electrical installations are carried out with safe equipment, in accordance with the provisions of Book 1 and with good practice where the Book is silent. What is added or modified therefore follows the current text.

Existing parts come under particular rules. Part 8 defines existing electrical installations, including old domestic installations whose execution began before 1 October 1981 (section 8.1.1), and grants them derogations. At the inspection visits provided for in chapter 8.4 for old domestic installations that have not undergone a compliance examination under the former RGIE, compliance is checked against Book 1, Part 8 included for the part whose execution began before Book 1 entered into force. How this applies to a specific installation is a matter for the accredited body. Identify circuit by circuit what is new or modified, then what that implies for the existing installation.

Significant modification or not: what the text says

Section 2.11.2 defines a significant modification or extension as one with an additional impact, not yet covered by a compliance inspection, on the safety of people or property. It gives as examples a change to the earthing system, exceeding the permissible short-circuit power for the installed equipment, the non-identical replacement of a distribution board, and the addition of a circuit to a domestic installation.

• Significant modification: compliance inspection before the added or modified part is put into use, limited to that part (subsection 6.4.7.3), and single-line diagrams and position plans drawn up by the person responsible for carrying out the works (subsection 3.1.2.1).
• Non-significant modification: a new single-line diagram is not mandatory; a brief description is enough, with the name, capacity and address of those responsible for the work, dated and signed by them. The modification is shown on the position plan (subsection 3.1.2.1).

The cases, from lightest to heaviest

• Extending an existing circuit. You add two sockets to a kitchen circuit: the new points and their wiring follow Book 1, and the extended circuit remains subject to the rules for the circuit. In domestic installations, subsection 5.3.5.2 for example limits the number of single or multiple socket-outlets to eight per final circuit. Our article on cable cross-sections and circuit breaker ratings covers how protection and cross-section must match.
• A new circuit. A circuit for an oven, a charging point or a heat pump is entirely new. Adding a circuit to a domestic installation is among the examples of significant modification: compliance inspection of the added part before it is put into use.
• A new board. The non-identical replacement of a distribution board is also listed as a significant modification. It is the moment to review how the RCDs are arranged, a point detailed in our article on 300 mA and 30 mA RCDs.
• A full renovation. For the sale of a dwelling with an old installation, section 8.4.2 provides that where the installation is fully renovated, the provisions of chapter 6.4 (compliance inspection before being put into use) apply.

For the schedule: the compliance inspection takes place before the installation or the significant modification or extension is put into use (section 6.4.1, subsection 6.4.7.3). Build it in from the quote onwards, rather than discovering it when the client wants to move in.

The impact on the electrical file

After a significant modification, the file of a domestic installation contains the corresponding diagrams, plans and reports, and after a non-significant one, its brief description (section 9.1.2). The inspection report also reminds the owner of the obligation to record in the file any modification made to the installation (subsection 6.4.6.4). In practice:

• Update the diagram with the new protective devices and cross-sections: this is mandatory for a significant modification; otherwise a brief description is enough (subsection 3.1.2.1). The full expectations are in our guide to the RGIE requirements for the single-line diagram.
• Update the position plan for every modification or extension: it gives the existing situation at all times (subsection 3.1.2.1).
• Number and date every version. Diagrams, plans and documents state unambiguously their number, version and the date of that version (section 3.1.2).

In an app like Amperio, the diagram and the plan are updated together: the circuit added at the end of the day goes into both documents instead of joining the pile of updates to do some evening.

The trap of the small modification

A limited intervention can have consequences for the existing installation. Subsection 6.4.7.3 provides that any modification or extension with an impact on the unmodified part is mentioned in the inspection report, and that this unmodified part undergoes a compliance inspection for the modified characteristics. Under subsection 4.2.4.3, where a significant modification or extension is made to an old domestic installation covered by Part 8, the whole installation is protected by at least one RCD of at most 300 mA at the origin.

That is no reason to avoid small jobs: properly anticipated, any work on the existing part becomes an extra assignment. For what Book 1 provides for the inspection of a significant modification or extension, see our article on how the RGIE inspection unfolds.

In practice: three questions before every job

• What is new or modified? List the circuits concerned: they follow the current Book 1. Determine whether it is a significant modification.
• What impact on the existing part? Modified characteristics, RCD at the origin for an old installation, condition of the board: all points to assess before quoting.
• Will the file keep up? Budget the update of the diagram and the plan in the quote, as a line item in its own right.

With these three answers, the boundary between new and existing becomes a clear line in the quote.

This article is informative. It replaces neither the RGIE (Book 1) nor the advice of your inspection body.