Exothermic Welding Powder: Complete Guide for Electrical Connections

Exothermic welding powder is what you use when you need a permanent, high-conductivity joint. Whether you’re buying it or useing it to weld, it helps to know what is it, what it’s made of, how the reaction works, and what safety steps to take. That way you’ll pick the right product and get reliable, long-lasting grounding and conductor connections.

Key Takeaways

• Exothermic welding powder creates permanent molecular bonds.
• Use the right powder size and graphite mold for safe, strong welds.
• Follow standardized welding operation process.
• UL-certified powder yields better reliability.

Content

1 What is Exothermic Welding Powder?
2 How Exothermic Welding Powder Works？
3 Types and Specifications
4 Applications
5 Quality
6 Tools

* Selection Guide
* Leading Brands and Suppliers
* Frequently Asked Questions

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1. What is Exothermic Welding Powder?

Definition and Basic Concept

Exothermic welding powder is a self-contained welding material.
It makes permanent electrical connections.
No external power or torch needed.
When ignited, it produces intense heat.
This heat melts metals and forms a molecular bond.
The result is a joint that conducts electricity like the parent metal.

“Exothermic welding creates a fusion weld — different from a mechanical clamp.”

Core Composition

• Primary ingredients: copper oxide and aluminum powder.
• Additional metals may include magnesium, iron, and other powdered metals.
• Typical composition often has around 70% aluminum content in the reactive mix.
• An ignition powder or starter charge triggers the reaction.

Commonly, manufacturers balance the mix for melting point, fluidity, and conductivity. The ignition charge is separate.

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2. How Exothermic Welding Powder Works?

The Chemical Process

A thermite-like exothermic reaction occurs between copper oxide and aluminum.
This produces molten copper alloy at very high temperatures.
Molten metal flows into the joint and fuses the conductors at the molecular level.
The result: excellent electrical and mechanical integrity.

Step-by-Step Process

1. Position conductors inside a graphite mold.
2. Place a metal retaining disc in the crucible.
3. Pour the exothermic welding powder into the mold cavity.
4. Ignite the starting powder with a flint gun.
5. The reaction creates molten metal.
6. Molten metal fills the weld cavity.
7. On cooling, a permanent molecular bond forms.

Short, clear steps. Simple to follow. But safety is essential.

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3. Specifications and Types

Specifications

• Usual cartridges: 45g, 65g, 90g, 115g, 150g, 200g, 250g.
• Packaged in plastic tubes. Boxes of 10–20 units depending on cartridge size.
• It is also packed in small bags sometimes.
• Some companies require exothermic welding powder to be packed in large barrels for shipment when purchasing.

Types

• Standard copper-aluminum cartridges: The most common type for general grounding and bonding.
• High-fluidity formulations: Designed to flow into complex molds or larger joint cavities, improving fill and reducing cold spots.
• Low-smoke / low-fume blends: Optimized for indoor or confined-space work where reduced emissions are important.
• Fast-ignition starters: Cartridges paired with enhanced ignition powders to ensure complete reactions in cold or damp conditions.
• Corrosion-resistant mixes: Include alloying elements that improve long-term corrosion performance in aggressive environments.
• Specialty metal powders: Formulations tailored for bonding dissimilar metals (e.g., copper-to-steel) or for specific conductivity/mechanical requirements.

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4. Applications

Primary Applications

• Copper-to-copper connections — ideal for splicing or extending conductors while keeping excellent conductivity.
• Copper-to-steel bonding — creates a metallurgical bond that ensures low resistance and long-term reliability between dissimilar metals.
• Grounding and bonding systems — permanent ground grid connections and equipotential bonding for electrical safety.
• Lightning protection systems — reliable, maintenance-free joints for down-conductors and air-termination networks.
• Substation grounding — meets demanding mechanical and electrical requirements for station earth mats and grounding meshes.

Specific Connection Types

• Cable-to-cable joints — splices for power, control, and earthing conductors of various sizes.
• Cable-to-earth-rod connections — secure, weather-resistant bonds between conductor and ground rod.
• Bar-to-bar welds — busbar and copper bar interconnections with low contact resistance.
• Cable-to-rebar bonding — integrating grounding conductors into concrete structures by welding to rebar.
• Cable-to-steel attachments — fastening conductors to steel structures or supports without mechanical clamps.

Exothermic welding is the preferred solution when a permanent, low-resistance, and maintenance-free electrical connection is required.

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5. Quality

• Material purity: High-purity copper oxide and aluminum powder ensure low, consistent weld resistance.
• Consistent formulation: Stable mix gives consistent reaction temperature and molten metal volume.
• Certification & standards: IEEE 837 compliance or UL certification confirm mechanical and electrical performance.
• Packaging integrity: Sealed, moisture-proof packaging protects the ignition powder and extends shelf life.
• Ignition reliability: Reliable starter powder and ignition ensure complete reactions in cold or damp conditions.

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6. Tools

Essential Equipment

• Graphite molds (specific to joint type).
• Handle clamps (small, medium, large).
• Flint guns for ignition.
• Cleaning brushes and tools.
• Metal retaining disks.

Safety Equipment

• Protective eyewear.
• Heat-resistant gloves.
• Proper ventilation.
  These protect operators from molten splash and fumes.

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Selection Guide

• Match conductor dimensions.
• Consider connection type.
• Account for number of welds.
• Choose by conductor cross-sectional area.

Correct choices reduce wasted cartridges. And improve first-pass yield.

Leading Brands and Suppliers

Brand	Country	Introduction	Website
Raychem RPG	India	Offers exothermic welding kits and accessories for reliable grounding. Focuses on field-friendly products and support.	https://www.raychemrpg.com/
FurseWELD (ABB)	United Kingdom	Part of ABB. Supplies exothermic welding materials for lightning and earthing systems. Emphasizes certification and global service.	https://new.abb.com/low-voltage/products/earthing-and-lightning-protection (ABB / Furse)
Cadweld (ERICO)	USA	Well-known exothermic welding system with consistent joint quality. Widely used in utilities and construction.	https://www.erico.com/ (search “Cadweld”)
Burndy	USA	Provides powders and connector systems for safe, efficient installations. Supports products with tooling and training.	https://www.burndy.com/
DEHN	Germany	Supplies exothermic materials within its lightning protection range. Focuses on high-quality protection components.	https://www.dehn-international.com/
Exoweld	South Africa	Manufactures powders and molds for grounding and lightning protection. Markets cost-effective kits for contractors.	https://www.exoweld.co.za/
AN Wallis	United Kingdom	Offers exothermic products for grounding and bonding. Highlights practical field solutions and local support.	https://www.anwallis.co.uk/

Frequently Asked Questions

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If you want, I can:

• Recommend the right cartridge for your conductor sizes.
• Schedule a 10~15 video meeting to answer more questions.
  
  Which would you prefer?

AUTHOR : Lucas Lyu