Carrying out a complete electrical rewire in a house is the kind of renovation that often raises plenty of questions about cost, timescales and safety. Unlike painting a room or replacing flooring, the cabling is hidden from view, which can make it harder to see where the money is going-despite the fact that the work follows clear technical criteria and can be planned with a reasonable level of predictability.
How much does it cost to rewire a house?
The price of redoing the entire electrical system depends on the floor area, the number of rooms, how many lighting and socket points are required, and the grade of materials chosen. In many Brazilian cities, it is common to combine a cost per square metre with the number of electrical points, adjusting the total to match what the design demands.
Lighting usually takes up a smaller share of the budget, whereas sockets intended for high-power appliances-such as air conditioning, showers and heaters-push the final figure upwards. Older properties typically require more corrective work, including replacing consumer units and chasing into walls, which increases both the time on site and labour costs.
Watch a video on the YouTube channel Mundo da Elétrica covering how to plan a residential electrical refurbishment, material costs and why it matters to hire qualified professionals:
https://www.youtube.com/watch?v=y3n9E94oI1M
Which factors have the biggest impact on the price of an electrical rewire?
When you choose to redo the electrical installation, several elements affect the budget directly-particularly if the goal is to prepare the home for modern equipment and future extensions. Beyond the quantity of materials, the overall cost also reflects planning, testing and any adjustments required to the structure of the property.
Among the items most likely to change the total cost, pay close attention to:
- Size of the house: a larger area means more cables, conduits and fittings.
- Number of circuits: more circuits improve safety, but require additional circuit breakers and more time.
- Material specification: well-known brands and devices such as RCD (DR) and surge protection (DPS) increase costs, but provide greater protection.
- Condition of the existing installation: very outdated systems demand more masonry repairs and compliance upgrades.
- Access difficulty: concrete slabs and older pipework can slow the job and make it more complex.
Why is it important to hire a qualified professional for electrical work?
Electrical refurbishments involve load calculations, selecting cable sizes, choosing circuit breakers and specifying protective devices against electric shock and surges. A mistake can lead to excessive overheating, frequent power trips and serious accident risks, which is why it is essential to follow technical standards such as NBR 5410 and the requirements of the local utility company.
With a suitably qualified professional, the homeowner receives correctly sized circuits, a layout of lighting and socket points that matches how each space is actually used, and provision for dedicated circuits for showers and air conditioning. Circuit diagrams or records also make future maintenance easier and help faults be located quickly.
What signs show it is time to rewire the electrical installation?
Before approving a full overhaul, it is worth confirming whether replacing the wiring is genuinely necessary. Certain warning signs indicate that the electrical system no longer matches today’s demand or may put residents’ safety at risk.
Circuit breakers tripping frequently, warm sockets, a burning smell, installations that have gone decades without updates, and heavy reliance on extension leads are red flags that need immediate attention. In many situations, a full rewire is more effective than isolated repairs and can be scheduled alongside other renovation work-such as changing finishes and repainting-to reduce disruption and avoid repeating the same messy work.
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