"This included using the logo of an independent testing laboratory on SE62 test certificates when the product had not been tested by the laboratory."
The charges stem from complaints about the validity of claims being made by three companies selling steel mesh in New Zealand,.
Charges were also filed earlier this year against Timber King Ltd and NZ Steel Distributor Ltd in relation to false and misleading representations about 500E steel mesh, the commission said.
These companies had entered guilty pleas and would be sentenced in court in August.
The commission expected to lay charges against one other company, and investigations continue into one additional company.
Steel & Tube pointed out in a statement that the charges related to "the application of testing methodologies only, not the performance characteristics of the seismic mesh".
"Steel & Tube has been cooperating with the commission throughout its investigation and was aware of the decision to file charges today. Steel & Tube is working with the Commerce Commission to reach an appropriate resolution of the charges, however cannot comment further as the matter is before the court," the statement said.
"Steel & Tube continues to stand behind its products, and since April 2016, all of the company's seismic mesh has been tested externally by accredited laboratories."