4.16–34.5 kV system design: switchgear, cable sizing, substation layout, relay coordination, and arc flash analysis for utility and industrial applications.

What voltage level should my project use?

The choice between 4.16 kV, 13.8 kV, 27.6 kV, or 34.5 kV depends on system size, distance, and utility POI voltage. Generally: <2 MW at short distances can use 4.16 kV; 2-20 MW typically uses 13.8 or 27.6 kV; >20 MW uses 34.5 kV. Higher voltage reduces cable current and losses but increases equipment cost.

Key Deliverables

• Medium voltage single-line diagram
• MV cable sizing and route design
• Switchgear specification (IEEE C37.20 series)
• Transformer specification (impedance, losses, cooling)
• Protection relay settings and coordination study

Why is MV arc flash so dangerous?

MV arc flash incident energy is typically 10-100× higher than LV systems because fault currents are large and clearing times can be longer (relay + breaker operating time). MV arc flash analysis per IEEE C37.20.7 uses a different methodology than IEEE 1584 for LV. Working on energized MV equipment requires Category 4 PPE or higher and should be avoided whenever possible.