Electrical renovation: five planning mistakes to avoid
Published on 31 July 2026 · Verified on 18 September 2026 · The Mestravaux.lu team
Mistakes go beyond a small board or too few sockets. They start with pricing without knowing existing condition, intended use and expected checks. Clarify five points with the electrician, without invented extra-cost figures or DIY sizing rules.
The essentials in 30 seconds
- Working equipment does not prove safety.
- Protection must suit the circuit and use.
- Confirm positions before finishing surfaces.
- Request test results and current records.
Do not decide from a photo or age
Creos recommends professional checks. A photo helps prepare a visit but cannot reveal all wiring or required measurements. Request assessed elements and limits. Age or board appearance alone cannot support an overall conclusion.
| Erreur | Coût si anticipée | Coût de la reprise après coup |
|---|---|---|
| Tableau sans réserve | 50 – 150 € (rangée supplémentaire) | 500 – 1 200 € (remplacement partiel ou total) |
| Câblage sous-dimensionné pour un gros équipement | Inclus dans le devis initial | 300 – 800 € (nouvelle ligne dédiée) |
| Un seul différentiel pour toute la maison | 100 – 200 € par différentiel supplémentaire | 300 – 600 € (répartition après coup) |
| Câblage repris après pose des cloisons | Coût standard de la rénovation | +100 à 200 % (ouverture et rebouchage, soit 2 à 3x) |
Fourchettes indicatives ; l'écart réel dépend de l'accessibilité des circuits et de l'ampleur de la reprise.
Distinguish protection functions
Schneider distinguishes overcurrent protection from residual-current detection of insulation faults; some devices combine them. Module count alone is insufficient. Have types, coordination and allocation justified. Do not alter ratings yourself to stop trips.
Assess future uses
Charging, a workshop or heat pump may change the project. State needs rather than imposing cable sizes or board rows. Separate current work, reserved provision and checks before expansion. Empty board space alone does not guarantee another circuit’s feasibility.
Your project deserves an accurate estimate — it's free.
Request a quoteDo not close walls before decisions
Coordinate sockets and controls with furniture, doors and appliances. Plan plumbing, joinery and finishing interfaces and record useful routes before closure. For late changes, compare options and making good; no universal price multiplier fits every job.
Require a verified handover scope
Request appropriate results, outstanding issues and documents. Separate internal checks from any network process. An invoice or working lights cannot replace a description of verification. Keep diagrams and labels for future work.
Frequently asked questions
Is a full board automatically safe or unsafe?
That fact alone cannot decide. Have the installation and expansion limits assessed.
Does adding protection solve everything?
No. Suitability for circuits and the whole installation must be checked.
Must future appliances be finalised?
State likely projects and assumptions; final sizing needs selected specifications.
Is a user test enough for handover?
No. Agree appropriate professional checks and evidence.
Should checks wait until a sale?
Seek professional advice for concerns or incidents before any transaction. Check project-specific obligations separately.
Take action
Your project deserves an accurate estimate — it's free.
Request a quote