Hot wire consumes more? We did the tests!

Did you know that when an electric wire is very hot it consumes more electricity? Have you ever imagined that this could be the reason for the increase in your energy bill? That is what we will show in this article. So, come on guys.

Does hot wire spend more?

Every time a wire or electrical cable receives more electrical current than it is capable of supporting, the cable heats up and its electrical resistance changes, that is, the hotter it is, the harder it is for electrons to pass through this cable, that is, the cable resistance increases.

In order to draw the proper conclusions, we decided to perform a test with a 2.5mm² wire, which supports an electrical current of approximately 24A and in this test we will subject the wire to a very high current, to heat the wire simulating an old cable or receiving a current greater than the rated current the cable can handle. Before we will measure the resistance of the cable with the multimeter, the resistance of this cable is approximately 0.1 ohms.

Standard wire resistance in normal condition.

Now let’s turn on our short circuit machine and notice that the wire gets hot quickly and starts to glow. With the clamp meter, it is possible to see that the electric current in this cable reaches more than 200A, but we disconnect the circuit before the wire breaks.

The wire quickly heats up and becomes incandescent, as it does not support the electric current.

When re-measuring the cable resistance, we noticed that exactly what we expected happened, a very high increase in cable resistance, which went from 0.1 ohms to more than 3000 ohms.

The resistance has increased by more than 3,000 ohms.

After the copper wire returns to normal temperature, its appearance is very different from the original. The same is true with flexible cables.

After the copper wire returns to normal temperature, its appearance changes.

The increase in temperature changes several properties of copper, including the mechanical properties. When the cable cools it is possible to see how much more malleable it is than before being heated.

The electric cable or wire that goes through this overheating several times, ends up causing the circuit to which it is connected to use more electrical energy, precisely because its original properties do not return.

Very old houses with old electrical installations can consume much more electrical energy because they have cables that have gone through this thermal stress several times. In the ABNT 5410 standard, the cable sizing tables take into account the maximum temperature that the cable can resist and the ambient temperature, so there are several sizing tables to take into account different temperatures.

Patches of sloppy showers, overloaded outlet circuits, and poorly sized cables are the main causes of heating in the electrical installation, which is currently one of the main causes of the increase in the electricity bill.

In case of a very high electricity bill, the first step is to hire an electrician so that he can analyze and evaluate the damaged electrical cables in the circuits. The copper appearance of the wires and cables is a strong indication that the cable is overheating, just analyze whether the cable has carbonized or zinabre tips, in addition to the copper being very brittle.