Garage consumer unit: a secondary unit to take the load off the house
A garage is home to more and more power-hungry equipment: a water heater, MVHR ventilation, a water softener, an electric gate motor, not to mention sockets and lighting. Rather than wiring everything back to the house's main consumer unit, it's often more sensible to set up a dedicated secondary garage consumer unit. It's the same principle as a secondary pool consumer unit: circuits for a specific area are grouped on a separate unit, for greater clarity and safety.
Why set up a secondary unit in the garage?
- Take the load off the main unit of the house, which is often already crowded after years of added equipment
- Group the circuits of a single area (garage, outbuilding) for clearer identification
- Plan ahead for new uses: an additional water heater, EV charging, washing machine and tumble dryer
- Make maintenance easier: work on the garage without cutting power to the whole house
The equipment typically found on a garage consumer unit
- Water heater(s): a dedicated circuit per unit, with its own circuit breaker
- MVHR: mechanical ventilation for the garage or the house
- Water softener: a dedicated electrical installation for the appliance
- Electric gate motor: a dedicated circuit for the automatic gate
- Washing machine and tumble dryer: increasingly installed in a garage utility room rather than in the house
- General lighting for the garage
- Sockets for tools and everyday use
Case study: a secondary unit to double up hot water production
Here's a job carried out by our electrician in Villeneuve-Loubet, in a villa in Hauts de Vaugrenier, allée des Alouettes. The client had a very concrete problem: a single water heater in the house, which fell short as soon as guests stayed over. Rather than replacing the existing water heater with a bigger model, he chose a different approach.
The client's requirement
The client wanted to move the water heater's power supply from the house to the garage, and install a second unit alongside it. In practice, this now provides two water heaters:
- A first water heater for the family's everyday use
- A second water heater, switched on only when extra capacity is needed: guests staying over, or a future addition to the family
This dual setup preserved all the day-to-day flexibility of a single water heater (no unnecessary overconsumption), while providing an on-demand reserve of hot water.
A secondary unit designed for every piece of garage equipment
While we were on site, we grouped all of the garage's electrical requirements onto this new secondary unit:
- The two water heaters
- General lighting for the garage
- The sockets
- A water softener
- The garage door motor
- An MVHR unit
The whole installation was fitted with Schneider Electric Resi9 circuit breakers and RCDs, spread across two rows with a supply comb to simplify the wiring and guarantee a tidy finish.
A reserve built for the future: the supply comb left free on the top row
An important detail of this job: we deliberately left the entire supply comb on the top row unused, without connecting any additional circuit breaker to it. This reserve lets the client easily add new equipment in future without having to redo all the unit's wiring, with one very concrete potential use in mind: installing an electric vehicle charging point, an increasingly common request for equipping a garage. Planning ahead for this kind of reserve capacity right from the design stage avoids a lot of complications the day the need arises.
This job is currently being finalised; we will update this page with a photo of the completed unit and the full circuit labelling once done.
For any questions or additional information, you can reach our electrician in Villeneuve-Loubet at 06 95 62 24 33, Monday to Friday from 9am to 6pm. Outside these hours, this line is reserved for emergencies, available 24/7.