Engineer's notes
About this lab: LV Switchgear Design Lab is a virtual workbench for low voltage switchboards, MCCs, final DBs, PFC, pump and ATS panels to IEC 61439. Pick a region and a type-tested system, size the incomer and busbars, check clearances, short-circuit forces and temperature rise, then see the panel as an SLD, a front GA, a 3D model, a 4D build and a 5D cost and carbon estimate.
Type-tested or custom
A TTA board stays inside the manufacturer's tested limits: rating, Icw, IP, form and busbar size. A PTTA board is your own design, so every clearance, support span and temperature rise has to be verified by calculation or test.
Icu, Ics and Icw
Icu is what a breaker can clear once. Ics is what it can clear and stay in service. Icw is what the busbars can carry for one second while the downstream breaker clears. All three must be above the fault level at the board.
Forms of separation
Form 1 has no internal barriers. Form 4b puts the busbars, each breaker and each set of cable terminals in its own compartment, so one feeder can be worked on while the rest stay live.
Heat is the hidden limit
Most switchboard problems in hot climates are thermal. Busbar derating, ventilation and the position of breakers in the panel matter as much as the ampere rating on the nameplate.
Topics: IEC 61439 design verification · busbar sizing · short-circuit withstand · clearance and creepage · temperature rise · forms of separation · ATS interlocking · panel BOQ
Related labs:
Switchgear & DB Checklist Suite
Busbar Riser Engineering Guide
Copper, Cable & Busbar Cost Lab
Switchgear Price & Variation Tracker
Standby Generators & Emergency Power
DEWA Design Tools
© 2026 Eng. Mannan Maqsood | Engineering Excellence Through Interactive Labs
Verify all figures against current manufacturer datasheets and local authority requirements before design sign-off. OEM limits, device dimensions, losses and prices in this lab are indicative.