 Usually operating at a lower arc voltage than the instant start design; no inductive voltage spike is produced for starting, so the lamps must be mounted near a grounded (earthed) reflector to allow the glow discharge to propagate through the tube and initiate the arc discharge.In some lamps a grounded "starting aid" strip is attached to the outside of the lamp glass.This ballast type is incompatible with the European energy saver T8 fluorescent lamps because these lamps requires a higher starting voltage than that of the open circuit voltage of rapid start ballasts.