Annex D and Annex E in national practice
The Netherlands and South Africa share one recorded departure from IEC 62305-2: Annex D and Annex E are not applied for usual studies. Here is what each annex does, and what is lost when it is set aside.
The Netherlands and South Africa apply the IEC 62305-2 method with the same recorded departure: Annex D and Annex E are not applied for usual studies.
Both entries appear in the same place, the list of differing practices in the foreword of IEC 62305-2:2024 at printed p.9, and both say the same thing. They are treated together here for that reason. Two countries, one rule, one page, rather than two pages differing only by a country name.
What matters is what each annex actually contributes, because setting an annex aside is only meaningful if you know what it was doing. Annex D changes how one probability is arrived at. Annex E adds a separate figure that never enters the main risk total at all. Their effects are therefore quite different, and lumping them together as "two annexes dropped" hides that.
What Annex D does, and what replaces it
PSPD is the probability associated with a coordinated surge protection system. In the ordinary route it is a table selection: Table B.7 for the low voltage system and Table B.8 for the telecommunication system, chosen against the protection level of the installed system. That value then feeds the internal system failure probabilities, so it carries directly into RC, RM, RW and RZ.
Annex D offers an alternative to the lookup. It lets an engineer arrive at PSPD from supplied probabilities rather than a table row, through equation (D.1), which forms it from PQ and PUp. The appeal is precision: a system whose real behaviour is better characterised than a table row allows can be modelled as it is, rather than rounded to the nearest protection level.
Where the jurisdiction does not apply Annex D, that route is closed for usual studies. Any Annex D evaluation an engineer has supplied is disregarded and PSPD comes from the Table B.7 and Table B.8 selections. The important word there is disregarded. The inputs may still be present in the model, so a tool that quietly ignores them without saying so produces a report whose numbers cannot be reconciled with its own inputs.
The direction of the change is not fixed. If the Annex D evaluation would have produced a lower PSPD than the table row, dropping it raises the computed risk. If it would have produced a higher one, dropping it lowers the risk. So this departure cannot be described as conservative or permissive in general, only case by case. Anyone telling you otherwise has not checked the numbers.
What Annex E does, and where its figure sits
Annex E accounts for harm beyond the struck structure. Understanding that its total stays outside R is what tells you what dropping it really costs.
Environmental components
Table E.1 defines counterparts of the risk components for damage to the surroundings. RAT, RAD and RU have none, because clause E.1 takes those as concerning only the struck structure itself. The remaining components gain an environmental form.
Presence and loss
The probability of presence PPE comes from equation (E.3), with tzE from Table E.2. Loss values follow equations (E.1), (E.2), (E.4) and (E.5), with typical values in Table E.3 for L1 and Table E.4 for L2.
Outside R, by design
The Annex E total stays out of R in equation (1). Clause 8.1 NOTE gives two alternatives for harm to the surroundings: add the consequent loss into the LX values, or use the Annex E concept. Taking both would count the surroundings twice.
Annex E defines no tolerable threshold of its own, which is the reason its total is reported beside R rather than added into it. There would be nothing to judge an inflated R against. So where Annex E is not applied, every environmental component is zero and the clause 7.3 comparison is untouched. What is lost is a stated figure for harm beyond the structure, not a stricter verdict.
What "for usual studies" is doing in that sentence
The entry says the annexes are not applied for usual studies. That qualifier is the standard's own, and it is worth reading literally rather than rounding to "the annexes do not apply". It describes the practice for ordinary assessments. It does not declare the annexes void, and it does not settle what happens when a project or an authority having jurisdiction specifically calls for a detailed Annex D evaluation or an Annex E treatment of the surroundings.
Both annexes are informative rather than normative, which is what makes a national practice of setting them aside coherent in the first place. Printed p.12 also lets national or local regulations fix the Annex A, B, C and E calculation rules and parameter values, so an authority has room to say something more specific than the foreword does.
The practical position on a project is therefore: apply the national practice by default, and treat a specification calling for one of these annexes as a question to resolve in writing with the authority having jurisdiction before the assessment is issued, rather than a conflict to resolve silently in a spreadsheet.
Netherlands and South Africa
The same rule, recorded separately for each country in the same foreword list.
EN IEC 62305, national publication
The Netherlands reaches the standard through the European adoption EN IEC 62305, published under a national reference. The technical content is the IEC 62305 content, with Annex D and Annex E set aside for usual studies as the sole recorded departure.
SANS publication
South Africa publishes the standard through its national body as a SANS standard, an adoption of IEC 62305. The recorded departure is the same one: Annex D and Annex E are not applied for usual studies. The rest of the method is the international method.
Neither entry records a national tolerable risk. Clause 7.3 NOTE 1 gives RT = 1×10-5 per year as a representative value of tolerable risk and adds that another value may be set once the case has been investigated in detail. Printed p.12 then lets national or local regulations fix RT, the tolerable frequency of damage FT, and the Annex A, B, C and E calculation rules and parameter values. So an assessment uses the representative value unless a specification, a regulator or the authority having jurisdiction names another.
Related reading
For the method these annexes sit inside, read the IEC 62305-2 risk assessment and how IEC 62305 risk is calculated. For the surge protection side that Annex D concerns, see SPD types in IEC 62305. For how national adoption works generally, see IEC 62305 around the world.
The other two recorded departures have their own pages: IEC 62305 in Germany, where rp is 1 for all cases, and IEC 62305 in Italy, where RL1 and RL2 are compared with the tolerable risk separately.
A disregarded input should be a stated one
Selecting the Netherlands or South Africa in Lumex closes the Annex D route and zeroes the Annex E components before the calculation runs. Where an Annex D evaluation was supplied and is being disregarded, the report says so rather than leaving a reviewer to wonder why an input appears not to have moved the answer, and every environmental component is reported as zero with the reason attached. A departure applied silently is worse than none, because a reviewer cannot tell a regulator's rule from a modelling error. See the Lumex platform.
Questions answered
Which countries do not apply Annex D and Annex E of IEC 62305-2?
What does Annex D contribute to an IEC 62305-2 assessment?
What does Annex E contribute?
Does dropping Annex E make the assessment less strict?
Does dropping Annex D make a result higher or lower?
What does the phrase for usual studies mean?
Lumex computes the IEC 62305-2 method and shows the working. It does not certify a structure. You may not issue or submit a Lumex output until a competent person, qualified where the structure is located, has reviewed the inputs and the result and signed it.
The tolerable risk in IEC 62305-2 is not a fixed constant. Clause 7.3 NOTE 1 gives RT = 1×10-5 per year as a representative value of tolerable risk and adds that another value may be set once the case has been investigated in detail. Printed p.12 then lets national or local regulations fix RT, the tolerable frequency of damage FT, and the Annex A, B, C and E calculation rules and parameter values. Every Lumex assessment states the jurisdiction it was computed under and the values that applied.