Joints: exothermic welding

Copper-clad steel selection guide, part 7 of 8

The material sets the ceiling; the joint sets the floor. CCS electrodes are joined by exothermic welding as a rule: GB/T 50065-2011 and DL/T 1312-2023 both recommend it, and technically it is the one method that satisfies the electrical, mechanical and service-life requirements at once (IEEE 837-qualified compression connectors are acceptable where hot work is restricted) – joint performance equals the parent metal, and the whole grid behaves as one continuous conductor.

Joint quality is judged mainly against DL/T 1342-2014 Materials and connectors for electrical earthing works (DL/T 1315-2013 deals mainly with the weld metal itself):

1. Appearance: smooth and full, no through-porosity, joint larger than the parent conductor in every direction – the most important and most overlooked item, and checkable by eye: pass = the weld fully encloses the conductors being joined; fail = it does not.
2. Electrical: DC resistance not more than 1.1 × that of parent material of the same size.
3. Tensile strength: not less than the parent material.
4. Electrical and corrosion test: resistance and appearance acceptable after the test sequence.

The quality of an exothermic joint is not "was it welded?" but "is there a complete, continuous, fully enclosing metal connection?". We ship moulds, weld powder and the welding procedure with the conductor, and can attend the first joints on site.