A lamp includes a linearly extending heat sink, blue-light-emitting LEDs mounted on the heat sink, and a light emitting cover mounted on the heat sink in line with the LEDs, a first portion of the cover opposite the LEDs including a phosphor that is excited by the LEDs to emit white light. The cover may be a tube with the LEDs outside the tube, a portion of the tube nearest the LEDs being transparent and receiving light from the LEDs. The tube may include reflectors that are attached to an exterior surface of the tube to hold the tube on the heat sink. Alternatively, the cover may enclose the LEDs on the heat sink, where a portion of the cover has an interior surface that reflects light from the LEDs to the first portion. The lamp may include electrical connections that allow for multiple lamps to be connected in series.