What is An Electrical Shower: A Complete Guide

What is an Electrical Shower?

An electrical shower is a shower unit that heats cold water instantly using an electric heating element. It draws water directly from your mains supply and uses power ratings typically between 7.5 kW and 10.5 kW to provide a continuous flow of hot water.

Meaning

When you switch on an electrical shower, cold water passes through a heating chamber that rapidly warms the water to temperatures usually between 30°C and 50°C (86°F–122°F). You control the heat level using a built-in thermostat, which adjusts the flow rate and power to maintain a stable temperature. Since no storage tank is required, an electrical shower can help you save space and energy, as it only consumes electricity when in use.

How Does Electrical Shower Work?

An electrical shower works by taking cold water from your mains supply and passing it through a high-powered heating element. When you turn on the shower, a flow sensor activates the element, which heats the water as it travels through the unit. Most electrical showers have power ratings between 7.5 kW and 10.5 kW, allowing them to raise water temperatures to a range of roughly 30°C to 50°C (86°F–122°F).

A built-in thermostat helps you keep the temperature steady by adjusting the water flow and power usage. This ensures that you get a consistent heat level throughout your shower. Because the water is heated on demand, you won’t need a separate hot water tank or boiler, which can save you both space and energy.

What is the difference between an electric shower and a normal shower?

The main difference lies in how each shower heads the water. An electric shower uses a built-in heating element to warm cold mains water on demand, so you only need a cold-water feed and a suitable electrical circuit (usually rated between 7.5 kW and 10.5 kW).  

In contrast, a normal shower relies on your home’s existing hot water supply, which typically comes from a boiler or hot water tank. This means a normal shower can deliver higher flow rates if your system is powerful, but you may run out of hot water if your tank’s capacity is limited. An electric shower, on the other hand, never runs out of hot water because it heats the water instantly as you use it.  

Does an electric shower use a lot of electricity?

Yes, electric showers can use a significant amount of electricity. Because an electric shower draws a high wattage typically 7.5 kW to 10.5 kW while it’s running, which might sound like a lot. However, you only use electricity for the duration of your shower. If you shower for about 10 minutes with a 9.5 kW unit, you’d consume roughly 1.58 kWh (9.5 kW × 10/60 hours).

Power Rating & Energy Consumption for Electrical Shower 

Typical Power Range: Electric showers have power ratings between 8 kW to 10.5 kW (kilowatts), depending on the model and flow rate. 

Energy Calculation: 
Energy (kWh) = Power (kW) × Time (hours). 
Example: A 10-minute (0.167-hour) shower with an 8 kW unit uses: 
8 kW × 0.167 h = ~1.33 kWh per shower. 

For a household with one daily 10-minute shower: 
1.33 kWh/day × 30 days = ~40 kWh/month.

How much does a 10-minute electric shower cost in Ireland?

To calculate the cost of a 10-minute electric shower in Ireland, you need three factors: the shower’s power rating (typically 8.5–10.8 kW), Ireland’s electricity rate (average €0.34–€0.40 per kWh as of 2024), and usage time.

Here’s the formula: 
Cost = (Power rating in kW × time in hours) × electricity rate. 

For example, a 9.5 kW shower running for 10 minutes (0.167 hours) consumes 9.5 × 0.167 ≈ 1.58 kWh. At €0.37 per kWh, this costs €0.58 per shower. Adjusting for variables: 

Lower power (8.5 kW): €0.52–€0.57. 

Higher power (10.8 kW): €0.61–€0.72. 

Your final cost depends on your shower’s exact wattage and energy provider. Reducing flow rate or using eco modes lowers consumption. Compared to stored hot water systems, electric showers are cheaper for short use but costlier over time if used frequently. 

Is an 8.5 or 10.5 kW shower better?

To decide between an 8.5 kW and 10.5 kW electric shower, consider your priorities:

Performance: 

A 10.5 kW shower heats water faster, delivering ~4–5 liters per minute (LPM) at a 35–40°C rise (from 10°C inlet water). 

An 8.5 kW unit provides ~3–4 LPM at the same temperature rise, requiring slower flow or cooler settings in winter. 

Energy Use: 

A 10-minute shower with a 10.5 kW model uses ~1.75 kWh (costing €0.60–€0.70 in Ireland), versus ~1.42 kWh (€0.48–€0.57) for 8.5 kW. 

Electrical Compatibility: 

10.5 kW showers need a 45A circuit; older homes may require wiring upgrades. 

8.5 kW models run on 37A circuits, often compatible with existing setups. 

Choose 10.5 kW if you prioritize strong flow, live in colder regions, or have modern wiring. Opt for 8.5 kW to reduce energy bills, avoid electrical upgrades, or for mild climates. Both offer similar durability, but higher power demands stricter safety checks (e.g., 30 mA RCD). 

Does an electrician have to fit an electric shower?

Yes, an electrician must fit an electric shower because it requires a dedicated electrical connection with the correct wiring, circuit breaker, and RCD (Residual Current Device) protection to ensure safety. Electric showers typically operate at high power ratings (7.5 kW–10.5 kW), which means they need a properly rated cable (usually 6mm² or 10mm²) and a separate circuit from the consumer unit. Incorrect installation can lead to electrical faults, overheating, or even fire hazards. While a plumber may handle the water connections, only a qualified electrician should carry out the electrical work to comply with Irish electrical safety regulations.

How many years should an electric shower last?

An electric shower typically lasts between 7 to 10 years, depending on factors such as usage frequency, water quality, and maintenance.