IEC 62305 in Italy
Italy runs the IEC 62305-2 method with one recorded departure in how the verdict is taken: R_L1 and R_L2 are each compared with the tolerable risk, rather than their sum.
Italy applies the IEC 62305-2 method with one recorded departure, and it sits in an unusual place: not in a parameter, but in how the verdict is taken.
Most national departures change a number. Italy's changes the comparison. The foreword of IEC 62305-2:2024 (Ed.3), in its list of differing practices at printed p.9, records that every risk is checked against the tolerable risk one by one, and that protection is achieved when both RL1 and RL2 come out below the tolerable value.
That single sentence changes which figure decides whether a structure needs protection. It also moves the verdict in the opposite direction from the one most readers assume. This page sets out what RL1 and RL2 are, what the rule replaces, which way it moves a result and why, and how it behaves on a multi zone structure.
Which publication governs in Italy
Italy reaches the standard the European way. CENELEC adopts IEC 62305 as EN IEC 62305, and the Italian body publishes that text under a national reference through CEI. The clauses, the risk components and the equations come across unchanged, which is why an Italian specification and an international one describe the same method.
Get the number right on a document. The current series is IEC 62305, and its adoptions carry the IEC number in their designation, as in EN IEC 62305. A bare EN 62305 names the superseded 2011 series. If a specification hands you that number, resolve which edition is actually intended before you calculate, because the edition decides the method.
For how national adoption works and what the other designations mean, see IEC 62305 around the world.
RL1, RL2 and the sum they make
Clause 6.3.2 splits the total risk by type of loss. The Italian rule is about which of these three figures the tolerable value is compared against.
RL1, injury to people, death included
The risk of injury to people, formed from the components carrying that loss. It is the half that holds the touch and step voltage terms RAT, RAD and RU, alongside the parts of RB, RC, RM, RV, RW and RZ that carry that same loss.
RL2, loss of service
The risk of loss of service to the public, formed from the loss of service terms of RB, RC, RM, RV, RW and RZ. It carries no injury components, because a touch or step voltage injury is an injury to people, not a loss of service.
R, their sum
Equation (6) states R = RL1 + RL2. The two are a partition of one total, built from the same components, not two independent calculations. That identity is what decides which way the Italian rule moves a verdict.
Clause 7.3 gives the baseline test: protection is needed when R exceeds the tolerable risk RT. So in the ordinary case the deciding figure is the sum, and RL1 and RL2 are a breakdown reported alongside it rather than a threshold in their own right.
Which way the rule moves the verdict
Read quickly, "each risk is compared with the tolerable risk" sounds like two tests to pass instead of one, and therefore stricter. The arithmetic says the opposite, and it is worth stating plainly because getting the direction wrong means specifying protection a jurisdiction does not require, or arguing for it against a client who has read the foreword.
Both RL1 and RL2 are non negative and they sum to R. So the larger of the two is always less than or equal to R. A structure that fails the baseline test, R above RT, can still pass the Italian test if the total is split between the two loss types such that neither half alone crosses the line. The Italian rule is therefore more permissive on the sum axis, not stricter.
The foreword requires only that both risks be below the tolerable value. It does not additionally require their sum to be. That is the whole of the rule, and reading an unstated extra condition into it is how a correct calculation ends up with the wrong verdict attached.
The cases where the rule changes nothing are the common ones. A structure with no loss of service exposure puts essentially all of R into RL1, so the two tests collapse into the baseline one. The rule bites where the total is genuinely split, typically a structure that provides a public service and also puts people at meaningful risk of injury.
How the rule behaves across zones
Clause 7.3 takes the verdict per zone, so the rule has to be applied per zone as well, not to a structure level total.
The deciding figure
Under the Italian rule the figure that decides is the worst of RL1 and RL2 across all zones, rather than the worst summed R. A structure passes only if every zone passes on both loss types, which is the same per zone logic clause 7.3 applies, taken on two figures instead of one.
Why zoning matters more here
Because the test is taken per zone on each loss type, how a structure is divided into zones affects which figures are compared. A zone that mixes a public service function with an occupied area produces one pair of figures where two zones would produce two, so the zoning decision needs to be made and recorded on its merits, not to reach a verdict.
The same holds for the frequency of damage test in clause 9.3, which is a separate comparison against the tolerable frequency FT. The Italian entry concerns the risk comparison; it does not change how the frequency test is taken.
RT is representative, not fixed by the standard
The value both figures are compared against is not a constant the standard imposes. 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.
The standard records no Italian value for RT, so an assessment uses the representative value unless a project specification, a regulator or the authority having jurisdiction names another. Under the Italian rule that choice matters twice over, because the same threshold is applied to two figures rather than one.
Related reading
For the method the Italian rule takes its verdict from, read the IEC 62305-2 risk assessment, and for how the components add up see how IEC 62305 risk is calculated. For how adoption works across markets, see IEC 62305 around the world.
Three other national departures have their own pages: IEC 62305 in Germany, where the fire provisions factor rp is 1 for all cases, IEC 62305 in Greece, where the thunderstorm warning system factor PTWS is 1 for all cases, and Annex D and Annex E in national practice, covering the Netherlands and South Africa.
Select the jurisdiction before you compute
Selecting Italy in Lumex changes the deciding figure to the worst of RL1 and RL2 across the zones, applied before the verdict is taken rather than annotated afterwards. The report prints both figures, the tolerable value they were judged against, and the departure with its citation, so a reviewer can see which rule produced the verdict and re-check it against the foreword. See the Lumex platform.
Questions answered
Does Italy use IEC 62305?
What are R_L1 and R_L2 in IEC 62305-2?
How does the Italian rule change the verdict?
Is the Italian rule stricter than the IEC baseline?
How does the rule apply when a structure has several zones?
Does Italy fix a different tolerable risk?
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.
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