An LED signal lamp comprises at least two separate LED arrays which have separate power feeds and wherein the LEDs of the arrays are positioned with respect to each other such that when lit they provide a composite light signal output and such that when the LEDs of only one of the two arrays are lit they provide a light signal with a visible distinctive pattern. A distinctive pattern is revealed, either lit or dark. Typically this pattern may be formed as a letter such as "X" or "F" or may be formed as a striped effect, for example. An LED signal apparatus comprises input signal power supply terminals 7,8 for the apparatus; a series connection of switch means S1 to S4 and a ballast load 6 connected across the supply terminals 7,8; an LED signal lamp 1,2 connected to the terminals to be supplied with current therefrom; and switch operating means D1 to D4, in the supply path to the LED lamp, for controlling the state of the switch means S1 to S4 in the series connection, whereby total failure or substantially total failure of the current to the LED signal lamp results in said switch operating means D1 to D4 causing said switch means to open to disconnect the ballast load 6 from power from the supply terminals 7,8.