adequate means for isolating servic

adequate means for isolating services Fire fighters' switches for luminous tube signs,etc.

isolations or cut-off switches to protect fire fighters must be provided for luminous tube signs or other similar equipment designed to work at voltages in excess of 1000 volts AC or 1500 volts DC if measured between any two conductors or 600 volts AC or 900 volts DC if measured between a conductor and earth