How to Splice Aluminum Wire | A DIY Guide To Splice Aluminum Wire


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The higher the electricity consumption in daily routine, the more critical it is to have a correct cable connection. For, this would ensure fire and electrical safety requirements. Therefore, we bring to you how to splice aluminum wire.

Nowadays, many apartments still have aluminum wiring. Many tend to use aluminum to copper wire pigtail in these cases. Aluminum to aluminum connections is usually much safer. Otherwise, if a light fixture or outlet needs to be replaced in such an apartment, a problem can arise. 

You may need to make use of aluminum to aluminum wire connectors.

Aluminum and Copper Connection

Direct connection of these metals is strictly prohibited and is a flagrant violation. So, take care.

Direct contact of copper and aluminum is unacceptable due to the incompatibility of these metals. Always in these cases, it is necessary to make use of a wire connector.

Under the influence of moisture, such a connection becomes unsafe: it can cause a fire.

How to Make a Good Splice?

  • Remove the insulation for about four screw diameters.
  • We clean the metal to shine and form the rings.
  • We put a spring washer on the screw, then a single washer, then a ring of a conductor, a single washer, a round of the second conductor, a washer, and a nut.
  • Tighten the screw and tighten everything until the spring washer straightens and pulls another half turn.
  • If the copper wiring is stranded, you must wire it first. Don’t forget that these connections should be checked periodically: the optimum frequency is once a year.

There are still apartments where the electrical wiring is done with aluminum wires. Because manufacturers of lamps and other electrical appliances today use copper as the preferred material, many doubt how to properly splice this.

Copper and aluminum have different electrical potentials, so a voltage will necessarily be formed between them. Aluminum wire connections are a little safer.

If this bonding of two metals were located in a vacuum, then the connection would last forever. The same cannot be said for an aerated atmosphere where there is moisture.

Aluminum connections are usually more secure than mixed connections. Experts have concluded that a potential difference of more than 0.6 mV is already dangerous for cable connections.

Such contact cannot be called long-term. As for copper and aluminum, the electric potential between them is 0.65 mV, which is higher than usual.

It results in a galvanic couple, as in a battery. Therefore, it is not allowed to connect them in electrical wiring. But what about those who have aluminum wiring diagram in an apartment or house?

Here there are several options:

You are twisting two wires.

The oldest option for connecting electrical wires is twisting. It is also the simplest.

We go back to the electrical potentials of metals. For aluminum with lead and tin solder, the potential difference is 0.4 mV. For copper, with solder, it is only 0.25 mV.

It turns out that if one of the wires to be connected is treated with this solder, they can be safely secured.

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Usually, the solder is applied to the copper wire. You can tin both single-core wire and stranded wire. In the second case, the veins must be twisted, and their number is taken into account. For cables with a large cross-section, three conductors can be tinned and for small cross-sections (no more than one mm²) – five conductors.

But even this connection option does not provide a 100% guarantee that the contact will work for a long time. There is such a concept as the linear expansion of metals. That is, under the influence of temperatures, they expand.

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When twisting, it is impossible to achieve a firm hold of the wires to each other. When expanding, gaps are formed between them, which reduce the density of the abutment. Ultimately, this leads to the conductive value decreasing.

This is the reason why twisting is rarely used today. In this whole process, it is essential to make use of aluminum wire connectors.

Threaded contact

Threaded copper connections with aluminum are believed to be the most reliable contacts that will serve trouble-free for the lifetime of the cables themselves.

The ease of connection and the ability to join several wires at one node make this type in great demand today.

Indeed, it is generally used to join cables with a large cross-section. The number of connected electrical lines will be limited only by the bolt’s length (screw).

We return to metals’ electric potential and determine that between aluminum and steel (all bolted elements are made), the potential difference is 0.2 mV, between copper and steel – 0.45 mV, which is less than the standard.

That is, oxidation does not threaten all metals present in the bond. The strength of the connection of aluminum wires with copper wires, in this case, is ensured by a well-driven nut clamp.

Steel washers are installed between the two cores as a contact limiter or circuit breaker. It is essential to see if your house with aluminum. A lot will depend on this.

How to Make the Correct Contact with a Threaded Connection

  • The correct way to connect copper to aluminum wire with each other, you must:
  • Remove the insulating layer to a length equal to four-bolt diameters. If an M6 bolt is used, the size of the open section should be 24 mm.
  • If the veins already have surface oxidation, then they should be cleaned.
  • The ends are rolled into rings with a diameter slightly larger than the bolt diameter.
  • In sequence, they have placed on the bolt: a single flat washer, any wire, a flat washer, the second wire, another flat washer, the washer, and a nut that is tightened completely.
  • Note that to fasten wires with a cross-section of no more than two mm² in this way, you can use an M4 bolt. If the copper wire is treated with solder, it is unnecessary to place a washer between the two conductors. The end of a stranded copper wire must be soldered.

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One-piece connection

This type of contact is similar to the previous one. Only it is one piece.

So if you need to add another wire to it, you will have to break the connection and do it in a new way. This contact is based on a rivet clamp.

The process itself is carried out using a unique tool called a riveter. Ends are cleaned from the insulation, as in the previous version.

The rings are made slightly larger than the rivet’s diameter (their maximum value is 4 mm).

  • First, the aluminum end is placed.
  • Then a flat washer and a copper end.
  • Then another washer.
  • Insert the rivet end into the riveter and squeeze the tool handles until it clicks, indicating that the steel rod has been cut.
  • The connection between dissimilar metals can be risky if you don’t know how to install it. So, be careful about it.

Terminal block contact

This type of connection between copper and aluminum wires is most often used in lighting fixtures. 

Pads are supplied with the fixtures. In terms of the connection’s reliability, they are inferior to the threaded contacts, but this is one of the simplest options.

It is not necessary to twist rings or tin the ends to make the insulation. It is required to strip the wires to a length of 5-10 mm and insert them into the device terminals’ slots.

The clamp is made with a screw. It will have to strain, especially for the wire to aluminum. If a terminal block connects copper and aluminum, the device cannot be placed under plaster.

It can only be used in enclosed boxes: in a junction box or a luminaire cover.

Aluminum Electrical Wiring, although old-fashioned, is much easier to repair. Aluminum wiring repair does not take as much action as Aluminum to Copper wiring. That is why many insurance companies consider this type of thing.

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How to Splice Aluminum Wire: FAQ

Can I splice aluminum and copper wire together?

Electricians can splice aluminum and copper wire together by using ideal aluminum to copper wire connectors. You cannot join them with a standard wire nut without dire consequences.

Can I splice it into an electrical wire?

No. Skilled electricians can splice wires safely, adding the length they need to reach their destination.

What is the best way to splice electrical wire?

  • Remove the outer sheath of the wire. Be sure to splice two parallel cables together. 
  • Strip the insulation from the conductors. 
  • Inspect the wires. 
  • Remove the knockouts from the junction box. 
  • Connect the cable clamps to the junction box. 
  • Insert the wires. 
  • Make the cable connections. 
  • Attach the box and cover plate.


It can be said that electrical issues are a bit tricky. Any lousy connection we make can end in a catastrophe. The idea, in principle, is to call a technician specialist in the subject. These usually use from a special connector to aluminum wire splices to ensure your connection.

However, if you think you can correctly do this type of splice, you can follow our advice. Make sure you have the right tools.

You must always follow the safety rules, and we remind you that electricity can be a critical issue if you don’t know how to use it.

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