Hello There are providers out there who will manufacture bespoke signage, but obviously the cost of this exceeds off the shelf signs. In catologues (safetyshop;Arco) there are various signs warning of electrical hazards using the lightening strike yellow triangle coupled with words of warning, which may fit the bill. I think that given the hazard mentioned, the provision of warning signs is minor detail. its more important that your risk assessment identifies this hazard and that controls are in place to reduce the risk. In my experience the documentation of a safe system of work or safe operating procedure, which should include a physical check for overhead electrical hazards is essential. Training against the SSOW should be carried out and recorded as well. Depending on how often this task is carried out it might even be worth introducing checklist style dynamic or site RA for completion by operatives before starting work Alan