S.C. Code Ann. § 39-9-50

Weights and measures traceable to the United States prototype standards supplied by the federal government, or approved as being satisfactory by the National Institute of Standards and Technology, are the state's primary standards of weights and measures and must be maintained in a calibration prescribed by the institute. All secondary standards may be prescribed by the Commissioner of Agriculture and must be verified upon their initial receipt and as often as considered necessary by the commissioner.