IEC 62305-4 · Ed. 3.0:2024 · surge protection measures

A coordinated SPD schedule that names no products.

The lightning protection zones, the earthing and bonding network, and — for every incoming service — the SPD test class, the required discharge current per mode of protection, and the voltage protection level ceiling. A specification you can put out to tender, not a part number from one manufacturer's catalogue.

The wizard and on-screen summary are free. The full clause-referenced report is a one-off purchase.

SPD1 at LPZ 0B/1

LPL I · TN · CT1
Power line · class I
25 kA
Iimp 10/350 per mode
Telecom line · class D1
2.5 kA
Iimp 10/350 per line
power → Annex C, Table C.3 (IEC 61643-11)
signal → Part 2, Table B.8 (IEC 61643-21)
→ same boundary, same strike, a factor of ten apart

Illustrative figures from the sample design — your own come from the engine, each with its clause citation and calculation trace in the report.

Signal lines are not power lines

Annex C's tables are keyed on the supply system and its modes of protection — they describe power lines. A telecommunication or data line is sized from IEC 62305-2 Table B.8 and classified under IEC 61643-21 as class D1 or C2. At LPL I that is 2,5 kA, not 25 kA: name the wrong table and you specify the wrong device.

The whole deliverable

Not just the SPDs: the LPZ layout with what each zone actually is, the bonding network and bar scope (§5.4), lead-length and ΔU checks, the back-up OCPD cases (C.2.8), separation distance and the coordination requirements that fall to the manufacturer's data — the document you hand a contractor.

What it does not do, in writing

Rule no. 2's case-specific evaluation, Annex E's simulated current sharing, PV d.c. and full LEMP studies are out of scope — and every report says so, with the clause. So is energy coordination between cascaded SPDs, which the standard itself defers to IEC 61643-12 and the manufacturer.

How it's validated →

How it works

1

Carry over the LPL from your risk assessment or LPS design

2

Declare the zones, supply and every incoming service

3

Read the coordinated schedule, per service and boundary

4

Unlock the clause-referenced report

Free to design. Pay only for the report.

Run the full wizard and read your on-screen design summary at no cost. A one-off fee unlocks the full clause-referenced report — the coordinated SPD schedule with every required current and ceiling, the calculation trace, the zone and bonding sections, and the assumptions and exclusions stated in full — as a printable document and PDF for the file.

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