Five locomotives were built, numbered 0001–0005. They carry a yellow and grey livery and are used by Eurotunnel for rescuing trains in the Channel Tunnel, and for propelling service trains in the channel tunnel. They are cleared to travel to Calais, Ashford, or St. Pancras; since 2007 they have been authorised to rescue trains on High Speed 1 in the event of a power failure. They have also been used to haul the SNCF TGV Iris 320 test train through the Channel Tunnel.
Following a series of tunnel breakdowns due to snow during winter 2009/10, during which the locomotives were extensively used, in November 2010 Eurotunnel announced it was to acquire two more "Krupp rescue locomotives"[note 1] with co-financing from Eurostar, at a cost of €1.3 million.[note 2] The locomotives acquired were similar NS 6400 locomotives bought second hand from DB Schenker Nederland, which were renumbered as 0006-0007.