Shower wire 110V and 220V! Which one to use? How to choose?

Do you know how to install a shower? Can you determine which cables and components should be part of this installation? See which cable to use in a 110V shower and what is the difference for the 220V shower. Understand the importance of using the circuit breaker when installing the electric shower. In this article, we will present all these answers, and offer several tips for not making mistakes when installing your shower, come on a person!

Although it seems very simple, the installation of an electric shower must be performed observing several criteria and standardized standards that guarantee the proper functioning and safety of users. Unfortunately, it is very common to find showers with serious flaws in their installation and one of the most serious is the improper use of cables and/or incorrect dimensioning of the circuit breaker, in addition to the poor connection of the shower cables, which often presents a problem of bad contact.

The use of badly sized wires and cables and unsuitable circuit breakers cause serious problems in the installation, for example, the melting of the cables and the insulating tape that insulates the connections and splices, as shown in the image below.

A poor connection can lead to improper functioning and heating of the components!

Shower 127V or 110V?

A very frequent question from users and even from electrical installation professionals is the difference between voltages 127V and 110V, and in Brazil, the voltage standard for residential and building use is 127V and 220V. The 110V voltage has already been used in Brazil and is still used in some countries, so all electrical equipment manufactured in Brazil is currently prepared to operate at 127v.

Therefore, if you order a 110V shower in the electrical supply store, the equipment voltage will naturally be 127V, that is, the 110V has become just a “reference” for the 127V. Currently, it is possible to find electric showers in different powers, among the most common are: the powers of 5500w and 7500w. It is still possible to find smaller powers such as 4500w and 3200w.

How to choose the right yarn?

For a correct installation, it is essential to know the power and voltage of the shower, then it is necessary to properly choose the section of the wire that will be used to power the shower and also the circuit breaker that will protect the installation.

Taking as an example a 127V shower with a power of 5500w, we need to know the rated current of the same, this information is usually on the product packaging or on the shower body itself, but don’t worry if you don’t find this information, just divide the power value by voltage as shown in the example below:

Power (W) and Voltage (V)

5500W / 127V = 43.3 Amps

After knowing the chain, we must choose a wire that is compatible with it, it is very common to find in the shower packaging the information of which wire to use, but we can also check in a table which is the minimum cable section for this chain found.

Nominal section mm² – Maximum current
2.5 24A
4 32A
6 41A
10 57A
16 76A

This table above is informative and for exact dimensioning other factors such as the cable installation method must be taken into account, this data is made available in standards.

It is essential to choose a cable with a current equal to or greater than the shower current, and according to the table, we must use a 10mm² cable that supports up to 57 amps. It is important to remember that the maximum distance also interferes with the cable capacity, so only adopt the table above when the cable length is less than or equal to 30 meters, for distances greater than this it is necessary to increase the cable section. For example, if a 10mm² cable is used for less than 30 meters, it will be necessary to use a 16mm2 cable for distances greater than 30 meters.

How to choose the circuit breaker?

The function of the circuit breaker is not only the protection of the shower but mainly the protection of the cable. That is why it is very important to choose a circuit breaker that protects the cable but does not turn off when the shower is turned on. The commercial values ​​of circuit breakers are:

  • 25A
  • 32A
  • 40A
  • 50A
  • 63A
  • 70A
  • 80A

As with wires, the value of the circuit breaker to be used is also easily specified on the shower packaging. Pay attention to the number of phases of the circuit breaker which for 220V must be bipolar and 127V must be unipolar. To facilitate the choice, consult the data below, where the main shower powers are found:

  • For a shower with a nominal voltage of 127V and 5500W of power, a 50A circuit breaker must be adopted and the cable section must be 10mm².
  • For shower with a nominal voltage of 220V and 6800W of power, a 32A circuit breaker must be adopted and the cable section must be 4mm².
  • For shower with a nominal voltage of 220V and 7500W or 7800W of power, a 40A circuit breaker must be adopted and the cable section must be 6mm².

In this video below it is possible to follow in detail the installation of a shower and in it you will be able to see in practice various information that we passed in this article. Check out several practical tips that can keep you from accidents and future problems.


Did you notice that it is not so difficult to select the correct cables and circuit breakers for electrical installation? In addition to providing more security, an adequate installation can have a much longer useful life, that is, justifying your initial investment. On the other hand, trying to save money on an installation using the inappropriate components, can cause serious problems and the cheap can be expensive.