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Electric Shower Wattage Explained

electric shower wattage kW

Purchasing a new electric shower requires careful consideration of a number of factors. The kW (kilowatt-hour, sometimes just called wattage) rating is your first consideration when choosing an electric shower – it comes before the aesthetics, shower head design, or brand. 

It can be confusing to figure out how much power an electric shower needs if you aren’t an electrician, but we’ll break it all down for you here so you can make an informed decision, in a simple, understandable format.

At the low end of the range, you’ll find electric showers with a 7.5kW rating and the most powerful electric showers are rated 10.5kW. This difference in kW translates to a higher water flow rate, meaning the shower is able to heat and dispense a greater volume of hot water. 

For example, a 10.5kW shower can produce 50% more hot water flow compared to a 7.5kW. The higher the wattage, the greater the volume of warm water that will flow from the shower head.

How Many Watts Should Your Shower Have?

You can tell the power of an electric shower by its kilowatt rating. They’ll typically be labelled as 7.5, 8.5, 9.5 or 10.5kW.

To get hot water out of an electric shower head, cold water must first be fed into the system and through a heating element, the more heat this element can radiate, the quicker the water will heat up, and the faster it can be released through the shower head. 

Higher kW (kilowatt-hour) = more heat. Lower kW = less heat.

inside high kW electric shower

An electric shower requires time to heat the water to a higher temperature, thus the water is released at a slower rate and with a gentler flow compared to a mixer shower.

Higher kilowatt systems were introduced to combat this issue and keep a constant high pressure even at elevated temperatures.

That’s why choosing a powerful shower is important if you want a lot of water flowing at the temperature you choose. Put another way, if you want hotter water at more pressure, you’ll need more power and a higher kW rating.

The finest power shower for your bathroom will depend partly on the water and electricity options available in your home. The size of your water tank and the consistency of the water flow throughout your home are good indicators of the wattage that will work best for you.

In case you have low or inconsistent water supply pressure of at least 1bar, consider installing an electric shower with a power output of 5 kW or 8.5 kW.

If you have a house with high water pressure of at least 1.5bar and have never had any issues with water flow in your home, you can get away with a high-powered 9.5 kilowatt (kW) or 10.8 kilowatt (kW) electric shower.

The devil is in the (technical) details when deciding on an optimal kW rating. In the absence of knowledge regarding the capabilities of your home’s electrical infrastructure, you shouldn’t rush into purchasing a high-powered electric shower, such as a 10.8kW model that boasts the best showering experience.

Make sure your fuse or circuit breaker has the correct amp rating to prevent an electrical failure. As a rule of thumb, the larger the kW rating, the greater the amps needed to power it. The supporting cable may also need to be adjusted or replaced to accommodate the electrical draw to a high kW shower.

Related: Electric Shower vs Power Shower

Here’s a good video that helps explain the details of shower wattages.

Is a 9.5kw shower powerful?

Yes, a 9.5kW shower is considered “powerful”. The maximum shower kW rating is 10.5, with 9.5 being the second most powerful available.

Can I replace an 8.5kw shower with a 9.5kw?

Yes, but you’ll need to check a few things first before making the switch. An 8.5kw shower will draw around 37 amps, and a 9.5kW shower will require a fuse with a 45A rating. Both showers require a 10mm² electrical cable, only the amperage requirements at the fuse box differ. Of course, always consult a qualified electrician before making any changes.