Code of Federal Regulations Title 29. Labor § 29.1926.951 Medical services and first aid

(1) Field work. For field work involving two or more employees at a work location, at least two trained persons shall be available.

(2) Fixed work locations. For fixed work locations such as substations, the number of trained persons available shall be sufficient to ensure that each employee exposed to electric shock can be reached within 4 minutes by a trained person. However, where the existing number of employees is insufficient to meet this requirement (at a remote substation, for example), each employee at the work location shall be a trained employee.