Exothermic Welding

Exothermic welding is a simple, economical method of making permanent, very high quality electrical earthing connections – the exothermic welding process uses the high temperature reaction of copper oxide and aluminium within a semi-permanent graphite mould to form electrical connections mainly between copper to copper or copper to steel.

Exothermic welding requires no outside source of power or heat – the system is also light and portable ideal for field use. Making an exothermic welding joint is a simple procedure which requires a mould, weld powder, handle clamp and exothermic welding tools.

Connections are tolerant to repeated fault currents, highly conductive, permanent and demonstrate excellent corrosion resistance – most exothermic connections have at least twice the cross-sectional area of the earthing conductors being jointed.

Pictured: Bare copper can be directly attached to rebar using rebar clamps for concrete encasement – here an exothermic welding system was used for this purpose. The concrete that will surround the rebar will act as a buffer, helping to prevent galvanic action from the soil.

• “Steel rebar embedded in concrete has approximately the same potential as copper, thus will not corrode” – IEEE Std. 142-1991 (IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems)

How to Make an Exothermic Welding Connection

Making an Exothermic Welding Cu-nnect joint is a simple procedure which requires a mould, weld powder, handle clamp and various tools and cleaning accessories as detailed below.

1. Position cleaned conductors into exothermic mould after ensuring mould is dry, by pre-heating or making a test joint
2. Lock mould with handle clamp and place metal retaining disc in bottom of exothermic welding mould crucible
3. Pour weld powder into mould and place small amount of welding powder on edge of mould for easy ignition
4. Close mould lid securely
5. Ignite starting powder using flint gun
6. The exothermic welding reaction occurs – wait several seconds to allow to solidify before opening the mould
7. Remove the weld and clean mould carefully before making next connection

The product table below provides an overview of the exothermic welding component parts to enable the jointing and connection of the following:

Exothermic Welding Bar to Bar

Exothermic Welding Bar To Earth Rod

Exothermic Welding Bar To Steel Surface

Exothermic Welding Cable To Bar

Exothermic Welding Cable To Cable

Exothermic Welding Cable To Earth Rod

Exothermic Welding Cable To Rebar

If connections shown do not meet your requirements please contact Thorne & Derrick. Special custom-made exothermic welding moulds can be produced to suit the earthing application.

Exothermic Welding Products
BB1 – Bar to Bar
BB2 – Bar to Bar
BB3 – Bar to Bar
BB7 – Bar to Bar
BB14 – Bar to Bar
BB41 – Bar to Bar
BR1 – Bar to Earth Rod
BR2 – Bar to Earth Rod
BS1 – Bar to Steel Surface
BS2 – Bar to Steel Surface
BS3 – Bar to Steel Surface
BS4 – Bar to Steel Surface
CB1 – Cable to Bar
CB4 – Cable to Bar
CB5 – Cable to Bar
CC1 – Cable to Cable
CC2 – Cable to Cable
CC4 – Cable to Cable
CC7 – Cable to Cable
CC14 – Cable to Cable
CR1 – Cable to Earth Rod
CR2 – Cable to Earth Rod
CR3 – Cable to Earth Rod
CRE1 – Cable to Rebar
CRE2 – Cable to Rebar
CRE3 – Cable to Rebar
CRE6 – Cable to Rebar
CRE17 – Cable to Rebar
CS1 – Cable to Steel Surface
CS2 – Cable to Steel Surface
CS3 – Cable to Steel Surface
CS7 – Cable to Steel Surface
CS8 – Cable to Steel Surface
CS9 – Cable to Steel Surface
CS25 – Cable to Steel Surface
CS27 – Cable to Steel Surface
RS1 – Stud to Steel Surface
RS2 – Stud to Steel Surface

Exothermic Welding Powders

AN Wallis Cu-nnect exothermic welding powders are a high quality mixture of copper oxide and aluminium – the starting powder is compacted at the bottom of each cartridge with the weld metal on top, the starting powder is released by firmly tapping the base of the cartridge.

Exothermic Welding Powders

Exothermic Welding Tools

Welding Handle Clamps

A Handle Clamp is required to hold the graphite mould and conductors in place whilst the connection is being made. There are three sizes of handle clamps shown in the table below:

Handle Clamps

Earthing

Copper electrodes (including earth tapes and rods), conductors, clamps and earth bonding bars provide lightning and transient overvoltage energy with a direct and effective low resistance route from the Earthing & Lightning Protection Systems safely to earth.

See full range of AN Wallis Earthing Products

Data Sheets

• Exothermic Welding Cu-nnect Product Catalogue
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