Many professionals balk at the $300+ price tag for a PDF. However, consider the cost of non-compliance:
Many universities, technical colleges, and large engineering corporations maintain licenses for standard libraries. If you are a student or employee, check your internal knowledge base or physical library. iec 61439-6 pdf
Form of separation (Form 1 to Form 4) applies to switchboards (IEC 61439-2), not busbar trunking. Busway uses IP rating and partial barriers for protection. Many professionals balk at the $300+ price tag for a PDF
Specifiers and end-users need the standard to write correct tender documents. Without it, you might accept a system that fails under harmonic loads. iec 61439-6 pdf