An LED based lamp comprises: an enclosure with an opening that comprises a light emission plane through which light is emitted from the lamp; a plurality of LEDs located along at least one wall of the enclosure and operable to generate light of a first wavelength range, wherein the LEDs are configured such that in operation their emission axis is oriented within a plane that is substantially parallel with or directed away from the light emission plane; and a first light reflective surface located on the base of the enclosure and configured such that in operation light is reflected through the light emission plane. A light emitting sign comprises the lamp of the invention with a light transmissive display surface overlying the light emission plane.