How is three grade steel connected to ground flat steel?
Steel bars welded with flat bars should be of little size, 12mm bar, and if you are not sure, you can use a section of HRB335 over.
HRB400 can be directly welded by hand arc welding with Q235 flat steel into electrical circuit. (I have done two sets of tensile tests last year, qualified).
Welding method, the steel bar placed in flat iron plane, welding length is not less than 12 cm, welding is ok.
