19.17. Which external lighting devices must be switched on on a motor vehicle in motion at night, during heavy rain, or in fog?
UAЯкі зовнішні світлові пристрої повинні бути ввімкнені на механічному транспортному засобі, що рухається, у темний час доби, під час сильного дощу або туману?
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This is a driving exam question from the Traffic Rules of Ukraine about safety when visibility is limited: at night, during heavy rain, or in fog. The correct use of external lighting devices simultaneously helps the driver better see the road situation and makes the vehicle visible to other road users, which directly reduces the risk of accidents.
The question tests knowledge of Section 19 of the Traffic Rules, specifically the requirements of point 19.1 a) regarding the mandatory use of main headlights on a motor vehicle when driving at night and in conditions of insufficient visibility (as well as in tunnels), regardless of road lighting. That is why the correct answer is formulated more broadly than “only low beam”: it is allowed to use either low or high beam (taking into account the general requirement not to dazzle other drivers), and this is a typical trap on the theoretical exam.
The analysis of the answers is simple: the option about fog lights is not a universal requirement, because they may not be present by design, and their use is regulated by point 19.5 and the note to 19.1 (in insufficient visibility they may be used, but do not replace the basic rule for nighttime). The “only low beam” option is too narrow, since the Traffic Rules of Ukraine directly allow low or high beam, so on the exam, the correct answer is the formulation with both permitted modes.
Clause 19.1 (Section 19 "Use of external lighting devices"), subclause a)
"At night and in conditions of insufficient visibility, regardless of the degree of road illumination, as well as in tunnels, the following lighting devices must be switched on on a moving vehicle: a) on all motor vehicles — dipped (main) beam headlights; b) on mopeds (bicycles) and horse-drawn carts (sledges) — headlights or lanterns; c) on trailers and towed vehicles — side marker lights. Note. In conditions of insufficient visibility, it is allowed to switch on fog lights instead of dipped (main) beam headlights on motor vehicles."
Application to the question: for a motor vehicle moving at night and/or in conditions of insufficient visibility (heavy rain, fog), it is mandatory to switch on the dipped or main beam headlights (as the basic requirement of this clause).
Clause 19.5 (Section 19 "Use of external lighting devices")
"Fog lights may be used in conditions of insufficient visibility either alone or together with dipped or main beam headlights, and at night on unlit road sections — only together with dipped or main beam headlights."
Application to the question: this clause clarifies the mode of use of fog lights, but does not cancel the basic requirement of clause 19.1(a) regarding switching on dipped (main) beam headlights on a motor vehicle when driving at night and/or in conditions of insufficient visibility.
Clause 1.10 (term "Motor vehicle")
"Motor vehicle — a vehicle driven by an engine. This term applies to tractors, self-propelled machines and mechanisms, as well as trolleybuses and vehicles with an electric motor with a power of more than 3 kW."
Application to the question: the question directly concerns a motor vehicle, for which clause 19.1(a) establishes the requirement regarding dipped (main) beam headlights.
Clause 1.10 (term "Night time")
"Night time — the part of the day from sunset to sunrise."
Application to the question: "at night" means "at night time" in the sense of the Traffic Rules, and it is for this condition that clause 19.1 establishes the obligation to switch on dipped (main) beam headlights.
Clause 1.10 (term "Insufficient visibility")
"Insufficient visibility — road visibility in the direction of travel less than 300 m in twilight, fog, rain, snowfall, etc."
Application to the question: heavy rain or fog may create conditions of insufficient visibility, under which clause 19.1(a) also requires switching on dipped (main) beam headlights (taking into account the note on the possibility of using fog lights in conditions of insufficient visibility).
Thus, the correct answer is "Dipped or main beam headlights.", given that according to the definition of the Traffic Rules, at night and in conditions of insufficient visibility, a moving motor vehicle must have dipped (main) beam headlights switched on (clause 19.1(a)).
When a motor vehicle is moving at night or in conditions where visibility is significantly reduced (for example, due to heavy rain or fog), the main purpose of lighting is twofold: the driver must see the road in the direction of travel and be clearly visible to other road users. That is why the Traffic Rules consider these conditions as requiring the mandatory use of the main headlights.
Clause 19.1 a) of the Traffic Rules establishes a direct requirement: at night and in conditions of insufficient visibility, motor vehicles must have their low beam or high beam headlights turned on while driving. Importantly, this requirement applies regardless of whether the road is illuminated by streetlights: if it is dark or visibility is poor, the headlights must be on.
In practice, this means that at night in a populated area with street lighting, you still turn on the low beam headlights (or high beam if permitted by conditions), because the rules require it. Similarly, if heavy rain or fog suddenly reduces visibility during the day, the vehicle must drive with its headlights on so as not to "disappear" in the weather conditions.
It is also important to understand the role of fog lights. Clause 19.5 allows the use of fog lights in conditions of insufficient visibility, but they do not replace the basic requirement to have the low or high beam headlights on at night: on unlit sections at night, fog lights are allowed only together with the low or high beam headlights. Therefore, the answer "low beam and fog lights" is not a mandatory requirement in every case, especially since a vehicle may not have fog lights at all in its design.
The option "only low beam" is also incorrect, because the Traffic Rules state the requirement more broadly: low beam or high beam is allowed (provided that high beam is used without dazzling other drivers). The exam specifically checks knowledge of this rule.
Thus, the correct answer is "Low beam or high beam headlights," since while driving at night or in conditions of insufficient visibility, the Traffic Rules directly require that either the low or high beam headlights be turned on in a motor vehicle.