How to properly connect aluminum and copper wire

Hello dear guests and subscribers of my channel. When doing minor repairs at home, we are often faced with the need to replace the outlet or switch, and sometimes we need to move it. In this case, the old wiring is most often built up.

And it's good if you have it completely copper, then there will be no problems. But what to do if you have old aluminum wiring and how to correctly and most importantly safely connect copper to aluminum. I'll tell you about this in detail now.

How aluminum cannot be combined with copper and why

First, I'll tell you how you can't make connections. So it is strictly forbidden to just take and twist two wires made of different metals. And there are several good reasons for this at once, which are closely interrelated, namely:

It is impossible to connect aluminum and copper, because they form a galvanic pair, and if such a twisting is performed in sufficient humid place, the moisture acts as an electrolyte and electrochemical corrosion will develop, which will destroy the connection.

It would seem that everything is simple, we twist in a dry place and nothing will happen. We just make a reliable contact (we twist aluminum and copper strongly) and order.

But there is a catch here. The fact is that aluminum is a rather soft metal and if after some time you inspect the twist of copper wire with aluminum, you will notice that the aluminum has "floated". Copper has practically no elasticity, and it will not restore the clamping force, and the contact will weaken.

Now let's remember that aluminum is a very active metal, and upon contact with oxygen, an oxide film is formed on its surface, which has insulating properties.

Since our contact has weakened, microscopic voids have formed between the veins, which will be filled with oxygen, which will react with aluminum and create a film, which means that the transition resistance will begin to increase at the point of contact.

So, under loads, such a twist will warm up and due to the heating-cooling cycle, the twist will begin to weaken, and a film will form even faster in the places of weakening. Thus, over time, the contact is worse, the heating is stronger, which can lead to a short circuit and even a fire.

Well, now let's move on to the correct options for connecting aluminum and copper wires.

Correct connection methods

So, there are several options for the correct connection of aluminum and copper wires, and I'll start with the simplest.

Vago terminal block

The fastest and easiest connection option is to use WAGO terminal blocks. The main advantage of this option is the speed and ease of connection. After all, it is enough to simply strip the wires, insert them into the slots and click the connector.

Also, for connecting aluminum wires, there are modifications with a special paste, which does not give aluminum oxidizes and thus the transition resistance decreases, which means that there will be no heating for this reason.

In addition, you can even connect a single-core aluminum wire with a stranded copper wire with such a terminal block. The main condition is to select the correct terminal itself so that its characteristics correspond to the conductors to be connected.

Everything is simple and convenient. But this option has several disadvantages, namely:

• A relative disadvantage, I can call just a huge number of fakes on the market. Because of what it is very difficult to find a really high-quality rail terminal block.
• The second drawback stems from the first and sounds like this: It is best to use WAGO for lighting and not connect power circuits with them.
• This option of connecting wires cannot be hidden in plaster. Since, according to the rules, you need to regularly (inspect the connection every six months).
• Another conditional drawback is the dimensions of the product. It is of course kept to a minimum in special editions.

Now let's move on to the next type of reliable connection of aluminum and copper wires.

Transitional terminal blocks

This connection option is devoid of the disadvantages of the above-described connection option, but even with this method there are some nuances:

• It will be very difficult to connect veins of different cross-sections in this way and in some cases impossible.
• The connection must be regularly serviced and the bolted connection must be tightened at least once every six months. Otherwise, due to poor contact, the junction will heat up, melt the insulation, short circuit and even fire is possible.

Otherwise, this is a very reliable connection option without cons.

Bolt connection

This connection option can also be called reliable, but personally I do not like it, and for the following reasons:

1. The connection is very bulky and almost impossible to neatly hide in a box.
2. Sufficiently high contact resistance. Despite the fact that the connection turns out to be reliable, under load it still starts to heat up a little.

Otherwise, a reliable connection, but more suitable as a "temporary house" somewhere in a barn, but not in a house or apartment.

Well, now I'll tell you about the most reliable connection

Connecting sleeves

The most reliable and durable connection is a special aluminum-copper connection sleeve. It is copper at one end and aluminum at the other (tinned sleeves are also suitable).

This connection option has only one drawback: you need to have special crimping pliers. Everything else, this connection is the most reliable and you can safely hide it in the wall without fear that over time the connection will weaken and start to warm up.

These are all options for the correct connection of aluminum and copper wires. When I need to "build up" the wiring and connect copper to aluminum, then I use car connectors in the lighting circuits, and only crimp terminals in the power circuits (sockets).

I ask you to write your opinion in the comments. And also if you liked the material, then rate it like it and share the material in your social networks. Thank you for reading to the end.