Home installations and efficiency

Explain what the main distribution board (consumer unit) of a home is, where it is usually located and what two functions it performs (distributing electricity and providing protection).

Circuit breakers (MCBs) and residual current devices (RCDs) are located in the consumer unit. Explain what each one protects: one protects the installation and appliances, and the other protects people.

The electrical installation is divided into circuits (lighting, sockets, kitchen...). Explain what a circuit inside a home is and give two advantages of keeping them separate.

The figure shows a domestic consumer unit through which electricity enters and flows out to the home's circuits, with an element marked with ?. State what this element is, explain when it trips, and what or whom it protects.

An oven rated at $3.000\ \text{W}$ and a dishwasher rated at $2.200\ \text{W}$ operate simultaneously in the kitchen. Calculate the total current flowing through the circuit using $I = \frac{P}{V}$ (mains supply voltage is $230\ \text{V}$) and reason why this circuit uses a circuit breaker with a higher amp rating than the lighting circuit.

In the electrical panel shown in the figure, a user notices that the $25\ \text{A}$ miniature circuit breaker (MCB) for the kitchen trips frequently when preparing food while the washing machine is running. A neighbour advises: "Replace that breaker with a $32\ \text{A}$ or $40\ \text{A}$ one; that way it won't trip again and you'll be able to turn on all three appliances at the same time".

1. a) Verify quantitatively whether the $25\ \text{A}$ breaker will trip when the oven ($3.000\ \text{W}$), the washing machine ($2.200\ \text{W}$), and the microwave ($800\ \text{W}$) are running simultaneously at a voltage of $230\ \text{V}$ ($P = V \cdot I$).
2. b) Technically refute the neighbour's advice: predict what will happen in the electrical installation's conductors if the MCB is replaced with one of a higher rating without changing the cable cross-section, justifying it using Joule heating and the risk of fire according to the REBT.
3. c) Propose a standard technical solution (circuit distribution according to the REBT) and a rational usage guideline that prevents tripping without the need for construction work.

Describe the path of water inside a house from the mains supply (the main inlet) to a hot water tap, naming the main stopcock and the water heater or boiler.

In the diagram of a house's plumbing system, the following appear in order: mains supply, main stopcock, water heater, and two branch pipes (cold water and hot water) leading to the bathroom and kitchen. Explain what each component does and reason why the hot water branch leaves after the water heater and not before.

In a detached house with a garden and underfloor heating, the main water meter registers an anomalous continuous flow rate of $15\ \text{l/h}$ overnight without any tap being open, but no visible damp patches can be seen on the walls.

1. a) Design a sequential diagnostic protocol to pinpoint which subsystem the leak is located in (indoor domestic cold/hot water network, closed heating circuit, or buried garden irrigation branch), specifying which shut-off valves to close and which pressure gauges or meters to check at each step.
2. b) Design the control algorithm for a smart home automation system equipped with an electronic flow meter at the service connection and a main shut-off solenoid valve. Define the logical conditions (instantaneous flow rate, accumulated volume, and continuous duration) for the system to accurately distinguish between normal use (shower, washing machine filling), a slow drip/hidden leak, and a catastrophic pipe burst, acting autonomously without triggering false cut-offs.

Name the three common indoor climate control systems in a home (heating, air conditioning and ventilation) and explain in one sentence what each contributes to comfort.

Explain what the main electrical switch and the main water stopcock are, and reason why the whole family should know where they are located (think of a water leak or an electrical fault).

Compare an instantaneous water heater with a storage water heater: how each heats water, when each system is preferable (occasional use versus multiple consecutive showers), and what keeping hot water stored 24 hours a day implies for energy consumption.

Explain what home automation (domotics) is and name three specific smart home applications that help save energy at home, stating what each one saves.

When plugging in a faulty appliance, the RCD trips and the whole house loses power. Explain what the RCD detected, what steps you would take to safely reset the installation, and why this switch must never be bypassed.

A family installs a programmable thermostat, occupancy sensors in the hallway, and timer control on the water heater. Explain how each of these three smart home measures saves energy.