1. Check the condition of the yoke before each use Check the power cord and switch to make sure they're in good condition. Check that the legs can bend to conform to the inspection surface. Check the feet to make sure they can make even contact with the inspection surface. The more contact area, the better. 2. Use a calibrated test weight to verify yoke strengthAn AC yoke must lift 10 lb. / 4.5 kg, and a DC yoke must lift 50 lb. / 22.7 kg. Using just any piece of steel for the dead weight check can create a hazard for the operator; if the weight is not balanced it could slip off the yoke and drop. Calibrated test weights include alignment features to keep the weight balanced on the yoke, allowing you to perform the dead weight check safely. 3. Follow the rated duty cycle The typical magnetic yoke has a 50% duty cycle with a maximum on time of 2 minutes. That means the yoke can be energized for up to 2 minutes continuously but would need to rest for the same amount of time afterward to prevent overheating. Exceeding the duty cycle can create a hazard for the operator and risk permanent damage to the yoke.