The three sets of requirements exist because the three bodies are protecting three different things, and each one is a licence to host something different.

LaLiga protects its broadcast product. Its television broadcasting regulations are written from the camera position outward: the league sells a television signal, and the lighting is what makes that signal saleable. It sets one level as the competition minimum, and a stricter one above it — LaLiga 4K, the highest standard in Spain — for the fixtures the league produces in 4K each week.

UEFA protects competition integrity across dozens of venues in dozens of countries. Its Stadium Lighting Guide sets requirements by level. Elite level A is the highest in Europe, and it is what qualifies a venue to host a Champions League, Europa League or Conference League final, or a European Championship final.

FIFA protects the tournament. Its Lighting Guide sets standard A, the highest level FIFA imposes, and the one that qualifies a venue for World Cup matches.

Two terms decide how the table reads. Horizontal illuminance is the light landing on the grass. Vertical illuminance is the light arriving on the player — what the camera actually sees, and the figure that decides whether a picture is usable.

One requirement sits outside the table because it is procedural rather than numerical: LaLiga measures every stadium before every season. Compliance is an annual audit, not a launch event.

Flicker tightens twentyfold. Under 20% for LaLiga HD, under 3% for UEFA, under 1% for FIFA. Flicker is the fluctuation in light output as the supply alternates: the eye misses it, a slow-motion replay does not, and it cannot be removed in post-production. It is a property of the driver electronics rather than of the LED, so two fixtures with identical photometric output can behave completely differently under a high-speed camera — and the difference appears on neither datasheet unless you ask for it.

They are not measuring the same thing. LaLiga measures vertical illuminance toward the twelve fixed cameras. UEFA and FIFA measure it on four reference planes, at 0°, 90°, 180° and 270°. One asks whether the cameras see well; the other asks whether the pitch is lit from every direction. A stadium can therefore satisfy its domestic league and be refused for a European fixture without a single value changing — and the fix is not more fixtures, it is re-aiming an installation whose mounting positions were set by a structural geometry fixed years earlier.

You have to design for failure. UEFA and FIFA both require a minimum adjacent uniformity ratio, MAUR, above 0.60 — how far the light level may drop between two neighbouring measurement points, in other words how visible the seams are between adjacent projectors. The condition attached is that it must hold with up to ten fixtures out of service. That is a design instruction rather than a measurement: fixtures serving adjacent zones cannot be grouped so that one failure opens a visible hole. The useful question to put to a supplier is not what the simulation shows, but what it shows with ten fixtures switched off.

There is no single strictest reference. LaLiga 4K sets the highest light levels — 3,000 lux horizontal, which covers UEFA's 2,000 and FIFA's 2,500 on its own — and the tightest uniformities with them. UEFA and FIFA set the tightest flicker and add MAUR, which LaLiga does not specify at all. The target is not one document but the union of the three.

The vertical case has to be demonstrated twice. Horizontally, meeting LaLiga 4K settles all three at once. Vertically it does not. LaLiga is satisfied by the light reaching its twelve fixed cameras, while UEFA and FIFA require the four reference planes at 0°, 90°, 180° and 270° to be shown separately in the calculation. That is two calculations, not one calculation read two ways.

Treat colour consistency as a supply question. All three set the same colour window, and LaLiga requires it to be consistent across every projector. Holding it across hundreds of fixtures, and still holding it in year eight, is decided at order — binning, single production batch — not at commissioning.

Do not leave the emergency case to the end. LaLiga requires backup within two seconds and at least 800 lux on the main camera, from projectors capable of instantaneous restrike. UEFA and FIFA permit no disruption at all. Any technology that needs time to warm up is disqualified there, whatever its photometric performance.

The Nou Mestalla will host LaLiga fixtures every other week and European football beyond that, so the pitch lighting is designed against the union of the three references rather than against the one that applies most often. Four decisions follow from that, and all four had to be settled at specification rather than at commissioning.

The design target is LaLiga 4K, not the competition minimum. LaLiga HD is the mandatory requirement; LaLiga 4K is not. Designing to it is what puts the stadium in contention for the fixtures the league produces in 4K each week, so this is a commercial decision as much as a technical one.

Colour is specified above the requirement. The pitch lighting is set at 5,700 K with colour rendering above 90, where all three bodies currently ask for a minimum of 80. LaLiga required 90 in a previous edition. Specifying to the higher value is protection against the next edition, not a flourish.

Every fixture is addressed individually. The installation is monitored and controlled unit by unit rather than zone by zone. That is what makes the ten-failure requirement manageable: you cannot design for failure if you cannot see which unit has failed. It also lets one installation hold a distinct lighting scene for each competition, without recommissioning between them.

Compliance is dimensioned for year eight, not for day one. All three set a maintenance factor of 0.90, and LaLiga re-measures every stadium before every season. The figures have to be met in the eighth year, with soiled optics and depreciated output — so the installation is dimensioned above requirement on day one in order to still sit inside it as it ages.

All four decisions are constrained by one thing that was not ours to choose: the floodlights are mounted on a gantry, and the gantry was in the drawings long before the lighting design began. Aiming, spacing and the grouping that the ten-failure requirement depends on are all worked out from positions that were already fixed.

Mounting positions are fixed by the structure. Colour consistency is fixed at order. Flicker performance is fixed by the driver electronics chosen at specification. By the time a stadium is being commissioned, the compliance outcome has already been determined — the measurements only confirm it.

Which is why the useful conversation about stadium lighting happens on the drawings, two years before anybody counts lux on the grass.