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Cadwelding or exothermic welding

Permanent molecular-bonded connections that will not loosen or corrode

cadweld connections 15mm electrode
Cadweld connections (Left) 15mm electrode to 70mm2 to 120mm2 (Right:) 15mm electrode to 120mm2

The ability of an earthing system to protect property and lives depends on the quality of its connections.

Connections are often the vulnerable points in an earthing circuit, particularly if they are subject to high currents and corrosion. It is vital that the connections in earthing and lightning protection systems are stable for the life of the system. If connections break, systems can fail.

Mechanical connections v cadweld connections
Mechanical connections can provide the required resistance at the time of installation, but with mechanical connections gaps and voids are inevitable and over time the gaps become prone to corrosion at the connection point and the corrosion increases the resistance of the earthing system.

Cadwelding creates electrically sound molecular-bonded contacts that are not susceptible to corrosion like mechanical connections. Cadwelding is recommended for securely connecting lightning protection and earthing conductors.

Cadweld connections are durable and have minimum impedance. Cadweld connections are not prone to elevated electrical resistance, they help reduce oxidation, and eliminate vibration-related weakening of connections.

What is the cadweld process?
The cadwelding process uses a chemical reaction between a thermite composition of aluminium powder and a mixture of copper oxides to superheat the copper alloy, and with the transfer of uncontaminated copper into the weld to create a gap-free permanent connection between the electrical conductors.

Cadwelding is also known as thermite or exothermic welding, with ‘exothermic’ referring to a reaction or process that is accompanied by the release of heat.

If done correctly, a cadweld is a true weld with the components being fully fused together.

Advantages of exothermic connections
Exothermic or cadwelding connections are far more effective than mechanical connections. Cadweld connections have the following advantages:
• They have the same current carrying capacity as the conductor
• Are highly durable and will not deform or deteriorate with age
• Are a permanent molecular bond that will not loosen or corrode over time
• Retain low resistance
• Can endure recurrent faults
• The process does not require an external heat source
• Can be quality checked visually
• Can withstand railway traffic without failing.

Specified and Australian Standard joints
Specifying the exothermic welding system can be critical to the life of an earthing system. State authorities including Transport for NSW, Sydney Trains and Sydney Water specify the cadweld joint method for electrical installations and it is also the preferred method for Australian Standard installation projects.

Earthing Solutions are cadweld-certified
Having been trained by industry leaders, nVent Erico, Earthing Solutions staff are cadweld-certified. Earthing Solutions specialises in cadweld joint installation and is a preferred and authorised nVent customer.

Earthing Solutions can guarantee and certify all cadweld joint installations that the company undertakes.