This clause of Part 1 applies except as follows: applies to both electrical and electronic equipment of sewing machines, sewing units and sewing systems, for professional use in sewing industry. Applies to equipment for industrial, commercial or laboratory, but not household applications (for details on the latter, see IEC Publication 335-2-28). Applies to sewing units and systems installed in dry and well-kept clean locations, e.g. in clothing industry, and which process dry sewing material. Where conditions are other than dry, well-kept and clean, more stringent measures may be necessary, which have to be agreed.