At most farmers markets around the United States, state inspectors use calibrated weight kits to validate and certify digital scales for commercial transactions. Laws and regulations can vary from state to state but generally it is a good idea to purchase a scale that is Class III NTEP approved, legal for trade. The scale will have a Certificate of Conformance (CoC#) that should be posted somewhere on the enclosure. Of course, this is something we’ve been saying for years and years but we still see sellers every now and then trying to use some cheap scale they bought on ebay for $35. In fact, next time you’re buying something over a digital scale like chocolate, candy, or frozen yogurt, take a look at the scale and see if you can find the CoC #. Take a look at the article below for additional info.
At farmers markets, growers have the option to sell produce by weight. If they choose to do so, they will need to meet the South Dakota laws regarding certified scales. South Dakota Codified Law requires any device used in a commercial transaction to be an approved NTEP (National Type Evaluation Program) device, meet the requirements of the NIST (National Institute of Standards and Technology) Handbook 44, and to be certified and sealed (inspected) by the State of South Dakota Department of Weights and Measures. This includes countertop scales, typically found at farmers markets. Inspecting a scale is beneficial to both the vendor and consumer, as it ensures both parties are receiving fair and equitable treatment. For example, consumers want to feel confident they are “getting what they pay for,” while vendors need to know they are not giving away their hard earned product.
Vendors should purchase a scale with a NTEP certification. This certificate indicates that the scale demonstrated the ability to be properly calibrated and can hold calibration over time. Keep in mind that no device is perfect and must be adjusted periodically. Scales can be purchased off the Internet, from scale companies in South Dakota, or additional locations you may select. – See more at: http://igrow.org/community-development/local-foods/farmers-market-operation-certified-scales/
We should also mention that you should get your scale checked and calibrated each year. We suggest doing this in February (or whenever your “slow” time of the year is) when your weighing needs aren’t quite as intense as they are in spring and summer. At this time you should make sure your scale is accurate and purchase any accessories like spare rechargeable batteries or keypads so there are no surprises during your busy time of the season.