Transformer labels tell people about the transformer. They show the voltage levels. They warn about the danger of shocks and arc flashes. They might also have instructions on how to operate the transformer. They include safety steps and rules about who can get near the transformer. For people who work near a transformer and for emergency workers, this information is what they need before they get close.

Transformers that are in boxes, on the ground transformers that do not use oil, transformers that use oil, transformers on poles, transformers that lower voltage and transformers that raise voltage, in factories transformers and transformers that control electricity inside electrical panels all need proper labels.

Labels go on the outside of the transformer box or case. They go on the door or panel that can be opened. They go on any part that has electricity. They go on the fence. Wall around the transformer, if it is in a special area. For transformers in boxes, on the ground, the label should be easy to see when someone comes to the entrance.

OSHA 29 CFR 1910.303 talks about how to mark and identify equipment. NFPA 70E covers labels that warn about arc flash dangers for equipment, including transformers. NFPA 70, also called the National Electrical Code, covers how to install and mark transformers. OSHA 29 CFR 1910.145 covers signs and tags that prevent accidents.

For transformers that have certain voltage thresholds, where an arc flash could happen NFPA 70E suggests labels that show the amount of energy from an arc flash, how far the danger goes, how close someone can get and what safety gear is needed. This information must come from a study done for each piece of equipment. General warning labels talk about the danger, while arc flash labels talk about the danger when working on live equipment.

Add them to your regular inspections for electrical safety. Replace labels that are not clear, have been damaged by weather or someone trying to break them, or no longer show the right information. For equipment, especially boxes on the ground, the sun and weather can make labels wear out faster than labels inside.