This invention relates to a detonating cord (10) having a core (12) of reactive material and a composite jacket around the core, and the method of its manufacture. The composite jacket includes an interior jacket (14) in contact with the core and a sacrificial jacket (20) disposed over the interior jacket. The sacrificial jacket prevents the cord from being cut off by the detonation of another detonating cord of like core load disposed adjacent thereto. The sacrificial jacket is separable from the interior jacket beneath it under the force of the adjacent detonating cord, thus absorbing energy and allowing the first detonating cord to remain intact. The detonating cord may have a core load of not more than 3.2 grams/meter (15 grains/ft) or, optionally, less than 1.25 g/m (6 grains/ft). The interior jacket may be free of metal jacket layers. Optionally, the outer cross-sectional diameter of the cord may be not more than about 3.8 mm (0.15 inch) so that it can be inserted into a standard detonator. The sacrificial jacket may be made from polyethylene and may have a thickness of about 0.25 mm (0.01 inch).