IEC 61439 did not make "type-tested assembly" the benchmark. It replaced the term in 2009 with three equivalent routes of design verification, and the 2020 edition says tests made to the old IEC 60439 need not be repeated where their results meet the current requirements. The Saudi documents we read cite the new series, and none asks for TTA. What changes is the rating, at 60 Hz and in Saudi heat.
Four ideas to carry into the next LV assembly specification you write or review.
IEC's own abstract: the TTA and PTTA distinction "is eliminated by the verification approach". The original manufacturer verifies each design by test, comparison or assessment, under a competent person (10.1, 2020 edition). No accredited laboratory is required unless the specification asks for one.
Nine items, 11.2 to 11.10, by the assembly manufacturer. Most begin as inspection; the dielectric check is made every time: 1 s at power frequency or, for incoming protection up to 630 A and 500 V, insulation resistance of at least 1 MΩ at 500 V DC (2020 edition).
SASO's 2023 EMC regulation lists SASO IEC 61439-1 to -6, undated. SEC 31-SDMS-07C Rev.0 cites IEC 61439-1 and asks 25 kA for 1 s. SABER's non-regulated list, read 9 October 2026, holds seven 12-digit codes under 8537.10; the code declared for the product decides the route.
IEC 61439-1:2020, 10.10.3.1: above 800 A a 50 Hz temperature-rise result is worth 95% at 60 Hz (2500 A becomes 2375 A) unless the rise stayed within 90%. Above a 35 °C daily mean, 10.10.3.6 recalculates the current: in a simplified example where a 70 K terminal governs, about 0.86 at 50 °C.
Every row names its clause and its edition. Rules marked 2020 were read from the published English text of IEC 61439-1:2020 clauses 10 and 11 and Tables 6 and 7; rows marked 2011 are a historical comparison.
| Requirement | Value | Source |
|---|---|---|
| The two words | design verification, routine verification | IEC 61439-1:2011, 3.9.1 and 3.9.2; 2020, 10 and 11 |
| Design verifications | 11 in 2020 (10.2 to 10.12), 12 in 2011 | IEC 61439-1:2020, contents |
| Routine verifications | 9, clauses 11.2 to 11.10 | Clause 11, both editions |
| Routine dielectric | 1 s, trip current at least 3.5 mA; alternative up to 630 A and Un 500 V: at least 1 MΩ at 500 V DC (2011: 250 A, 1000 Ω/V) | IEC 61439-1:2020, 11.9 |
| Design dielectric | power frequency 60 s by test; impulse by test, AC or DC alternative, or assessment with clearances at 1.5 times Table 1 | IEC 61439-1:2020, 10.9.2, 10.9.3 |
| Normal service ambient | 40 °C peak, 35 °C 24 h mean | IEC 61439-1:2011, 7.1.1; 2020, Table 6 note |
| Terminal rise limit | 70 K, or the component maker's lower limit, at a 35 °C daily mean | IEC 61439-1:2020, Table 6 |
| Ambient adjustment | by agreement, 20 to 50 °C, I1/I2 = (ΔT1/ΔT2)^0.61; example: 0.86 at a 50 °C mean for a 70 K terminal tested at its limit | IEC 61439-1:2020, 10.10.3.6 |
| 50 Hz result at 60 Hz | unchanged to 800 A; above, 95% unless the rise stayed within 90% | IEC 61439-1:2020, 10.10.3.1 (same in 2011) |
| Peak withstand floor | n = 2.1 from 20 to 50 kA: 25 kA needs Ipk of at least 52.5 kA | IEC 61439-1:2020, Table 7 |
| Short-circuit exemption | Icw or Icc up to 10 kA; current-limiting cut-off up to 17 kA; small auxiliary transformers; converter outputs limited to 17 kA | IEC 61439-1:2020, 10.11.2 |
| SEC LV panel | 25 kA for 1 s; temperature rise at most 60 K (SEC writes 60 °C) above SEC's maximum ambient of 55 °C; instruments keep their own limit; IP54; 75 °C sun on metal | SEC 31-SDMS-07C Rev.0, 10/2020, 7.1.2; 55 °C via 56-SDMS-05; read 2026-10-10 |
| Saudi adoption | SASO IEC 61439-1, -2, -3, -5; SASO GSO IEC 61439-6; undated | SASO EMC regulation, Annex 1-a |
| SABER status | seven 12-digit codes under 853710 on the non-regulated list; the declared code sets the route | SABER, read 2026-10-09 |
Each one changes a line of a tender or a submittal review.
A common reading says a 50 Hz short-circuit test "crosses unchanged" to 60 Hz. It does not follow. IEC 61439-1:2020, 10.11.5.4, runs AC short-circuit tests at the assembly's rated frequency with a ±25% tolerance: a tolerance on the test, about a frequency the manufacturer has declared (5.5). A panel rated 50 Hz is not a 60 Hz panel until its manufacturer declares the 60 Hz ratings.
Clause 10.1 (2020) puts design verification under the original manufacturer's responsibility, carried out or supervised by a competent person, with the method chosen by the original manufacturer. The GCC low-voltage regulation, BD-142004-01, permits accredited in-house laboratories. SABER's non-regulated list, read 9 October 2026, holds seven 12-digit codes under 8537.10, which take a supplier self-declaration and a shipment certificate; the code declared for your product decides, so confirm it on SABER before shipment. ASTA or KEMA certification is a commercial assurance layer a contract may require; an ASTA "Certificate of Short-Circuit Rating" covers short circuit only.
IEC 61439-1:2020, 10.10.3.2: functional units of the same group, the same type of construction, the same or larger dimensions and cooling, the same or lower internal separation and losses. 10.10.3.3: an aluminium-busbar rating is valid for copper of the same section, never the reverse. 10.10.3.5: a device up to 1600 A may be swapped for another series or maker if its power loss and terminal rise are the same or lower under its product standard, with the physical arrangement kept; short circuit is checked separately (Table 13). And 10.1: if a verified assembly is modified, new verifications are carried out where an adverse effect is likely.
Clause 10 of IEC 61439-1 has no internal-arc verification in either edition. IEC TS 61641:2026 (Edition 1.0, 19 August 2026) replaced IEC TR 61641:2014 and absorbed IEC TS 63107:2020. Its abstract describes passive protection by construction (door locks, hinges, pressure relief, barriers), active protection with an internal arc mitigation system (IAMS), and arc-ignition protected zones. It states that it does not consider conditions during maintenance work or the PPE used, so a classification does not authorise live work. AFLR is the medium-voltage classification of IEC 62271-200. Specify the zones, the permissible arc current and duration and the protection type as a contract term; Icw is not an arc rating.
In the 2011 text, clause 6.1 asks for at least four items on the designation label, the last being "IEC 61439-X" with the part identified: a label reading only "IEC 61439" is incomplete. The 2020 clause 6.1 was not re-read for this page. For the specification itself, IEC TR 61439-0:2022, Guidance to specifying assemblies, is the part of the series written for consultants, aligned with the 2020 edition.
Five lines, each naming a document, a quantity or a record. None of them says TTA, and none can be answered with an adjective.
a. Assemblies to IEC 61439-2:2020 with IEC 61439-1:2020 (SASO adoption, edition confirmed with SASO); the label names the part.
b. Design verification report for the arrangement offered, route per Table D.1 row, Ing or Inc declared at 60 Hz; routine record per serial number.
c. Rated currents at the site's stated 24 h mean ambient, by test or 10.10.3.6, limiting component and method shown.
d. Icw in kA for a stated time with Ipk, or Icc with its named protective device, at or above the prospective current; any 10.11.2 exemption stated with its condition.
e. Form of separation and maintenance case agreed; any internal-arc requirement to IEC TS 61641:2026, naming zones, arc current, duration and protection type.
Line c is the Saudi line: a rating at a 35 °C daily mean is not a rating in a hotter room.
NLC builds low-voltage distribution boards to IEC 61439. For any board, ours or anyone's, ask for the design verification report for the arrangement you are buying, with its 60 Hz ratings (Ing or Inc) and the ambient they are stated at, and the routine verification record for your serial numbers.
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The clause, the edition, and which document owns it. Where only part of a document was read, the entry says so.
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