Applies to low-voltage switchgear and controlgear assemblies (types-tested assemblies (TTA) partially type-tested assemblies (PTTA) and non type-tested assemblies (NTTA), with rated voltages not exceeding 1000 V a.c. at rated frequencies not exceeding 60 Hz or 1500 V d.c. for use in ships as a supplement to IEC 60439-1.