When cable trays contain conductors rated over 600 volts they are required to be marked “DANGER — HIGH VOLTAGE — KEEP AWAY” at no further than 10-foot intervals. What has changed is the way those labels are required to look in order to adequately warn of the. It is quite common to see cable trays used to carry DC PV source circuits operating over 600 volts. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned. Protect workers and visitors from electrical hazards with our durable electrical warning signs. Designed for maximum visibility, compliance, and long-lasting performance, these signs clearly communicate the presence of high voltage, shock risks, and other electrical dangers.