Most ELRs do not tell the user the level of earth leakage current in the protected circuit. The user is usually caught off-guard when the electrical supply is suddenly cut off. Such sudden tripping results in inconveniences and loss of productivity. Hager ELR, model HR421, HR422 and HR423, comes with an optical scale to show the user the level of earth leakage current so that the user can plan to conduct preventive maintenance of the installation / equipment. The sensitivity and time-delay settings on the ELR are adjustable and can be sealed.