Before entering the article, it is important that you know the functionalities that thermal switches and circuit breakers fulfill.

Both serve to cut the electricity. They are an essential element of security within the electrical installations in our homes and businesses.

Circuit breakers

They are those automatic electricity switches. They are responsible for protecting people and electronic equipment against sudden surges, electrical intensity or short circuits.

Next, in this blog article we expand the information on what a circuit breaker is and what it is for.


We are facing a type of circuit breaker that is made up of two metals that have a different coefficient of linear expansion. In the event that the intensity of the electrical energy raises the temperature of these metals, a curvature will occur that will interrupt the electrical circuit.

Thermal key or differential circuit breaker, what should we place in our home?

This will depend on the amperage that our electrical installation supports. We must know that a one-millimeter electrical cable supports around 5 amperes. If the electrical current that this cable is carrying is higher, it can cause a short circuit.

In order to avoid this, we will have to install a thermal key with a thermomagnetic switch, yes, the actuation amperage has to be less than the electrical circuit of our home.

How to connect the connection of the thermal switch and the circuit breaker in my house?

The first thing is that we will have to determine is how many thermal switches and differential circuit breakers we need to have a safe electrical installation in our home. The houses have, as a general rule, a maximum of 15 openings.

To determine the necessary amperage, we must find out what the intensity of the circuit is. The calculation is carried out through the following formula, Intensity is equal to Power over Energy multiplied by cosine of pi, which is a constant with a value of 0.9.

Now we go for an example. Suppose we have a circuit with 6 100Watt sockets and 4 200Watt sockets. The power is equal to 1400Watts divided by 220V and multiplied by 0.9 gives an intensity of 5.55 A.

Finally, to obtain the value of the thermal key to be purchased, the intensity must be multiplied by the coefficient of simultaneity. Assuming that it is 0.8, it gives us a value of 4.4. In this case the thermal must be 5 A.

Heated faucets come in the following amperage, 5, 6, 10, 15, 16, 20, 25, 32, 40, 50, 63, 80, and 100.

How are we going to install thermal and circuit breaker?

Once we are clear about how many thermal switches to install, we will see how to install thermal and circuit breaker.

The procedure is very simple. Follow these steps:

  1. We must place the differential circuit breaker at the input of the circuit.
  2. Afterwards, each thermal key will be installed with its own circuit.

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