Warning lamps are meant for lighting of communication roads in case of power network failure. Continuously active (M-type) lamps will stay on after a short switchover period, non-continuous (NM-type) lamps will switch on after failure of the normal network. Switchover / switch-on time is shorter than 1 second. Lamps of TLBV-118 type can be optionally adjusted to continuous or non-continuous operation. With lamps of TLBV-28 type, one light source / two light sources selection is possible (6 hours or 3 hours of bridge-over time). Lamps of the TLBV-18 type afford IP65 protection degree.