Agricultural Trailer Lighting Requirements in NZ: Lamps and Markers

Agricultural trailer lighting requirements in New Zealand come from the Land Transport Rule: Vehicle Lighting 2004 and related Land Transport Rules, administered by NZ Transport Agency Waka Kotahi (NZTA). An agricultural trailer used on the road normally needs rear lamps, stop lamps, direction indicators, red rear reflectors and, where it carries a plate, number plate lighting. Wider, longer or heavier trailers can need extra lamps, reflectors and markings.

That is a bigger list than many farmers expect, and stop lamps and indicators matter on any farm trailer that hides the tractor’s own rear lamps. This guide covers each lamp and marking in turn, with colours and practical mounting advice, then lighting boards for towed equipment, the 7-pin and 13-pin plug, wide and long trailers, and what gets checked at the roadside.

Which rules apply to agricultural trailers

The principal rule is the Land Transport Rule: Vehicle Lighting 2004, which sets which lamps vehicles must carry, their colours, and how they must be fitted and used. Agricultural vehicles, including agricultural trailers, have their own treatment within the Land Transport Rules, with specific provisions on lighting, width and speed.

Other Land Transport Rules cover vehicle dimensions and mass, braking and towing, and NZTA Waka Kotahi publishes guidance for agricultural vehicles that pulls these together for farmers and contractors. For the tractor side of the rules, see tractor lighting law, and check NZTA Waka Kotahi’s agricultural vehicle guidance for the current detail for your machine.

Agricultural trailer lights: the lamp-by-lamp table

The table below shows what an agricultural trailer drawn by a tractor normally needs on a New Zealand public road. The positions column gives good practice; check NZTA Waka Kotahi’s rules for the exact requirement for your trailer, especially for larger or older trailers.

Lamp or reflector	Required on an agricultural trailer?	Colour	Number	Position and notes
Rear lamps (tail lights)	Yes	Red	2	One at each rear corner, as close to the outer edge as the body allows
Stop lamps	Yes	Red	Usually 2	Worked by the tractor’s service brake; normally combined with the tail lamp
Direction indicators	Yes	Amber	1 rear on each side	Flash in time with the tractor’s indicators and with the hazard switch
Side lamps (front position lamps)	Recommended where the trailer is wider than the tractor	White	2	Front corners, facing forward, near the outer edge
Number plate lighting	Yes, where a rear plate is carried	White	As needed	Must light the rear plate; wired with the tail lamps
Side marker lamp	Can be required on long trailers	Amber	At least 1 each side	Check NZTA Waka Kotahi’s rules for the length at which they apply to your trailer
Rear reflective markings	Can be required on heavy or oversize trailers	Retro-reflective	As specified	Check the NZTA rules for your trailer
Side reflective markings	Can be required on long trailers	Retro-reflective	Both sides	Check the NZTA rules for your trailer
Oversize warning signs	Required on some oversize agricultural vehicles	As specified	As specified	Depends on width and length; check NZTA Waka Kotahi’s oversize guidance
Rear retro reflectors	Yes	Red	2	Trailer reflectors are normally the triangular type
Side retro reflectors	Recommended on long trailers	Amber (rearmost may be red)	2 or more each side	Spread along the body
Reversing lamps	No	White	Not more than 2	Only lit while reversing

Rear lamps

Rear lamps are the 2 red tail lights that show the trailer’s presence and width from behind. Every agricultural trailer used on the road at night needs them, and they must be lit during the hours of darkness (in general, half an hour after sunset to half an hour before sunrise) and in poor visibility. Some trailers used only in daylight can have fewer requirements under the NZTA rules, but any lights fitted to them must still work.

Fit the lamps at the rear corners, as close to the outer edge as the body allows, so drivers behind can judge the trailer’s width. On trailers with high bodies and wide flared sides, a lamp board or a second pair of lamps placed where they can be seen helps. The tail lamps must be clean and unobscured. Browse our rear lamps for combination tail, stop and indicator units in bulb and LED.

Stop lamps on agricultural trailers

Stop lamps on agricultural trailers are required in many situations in New Zealand, and are good practice on every trailer that goes on the road. Older advice often treated trailer brake lights as optional, but a trailer usually hides the tractor’s own stop lamps, so drivers behind depend on the trailer lamps to know when the combination is braking.

Stop lamps must be red and come on when the tractor’s service brake is applied. They are normally combined with the tail lamp in a single rear cluster using a P21/5W (380) twin-filament bulb or an LED equivalent. The safe rule is to replace lamps like-for-like with approved units, such as lamps showing an E or e mark.

Direction indicators and hazard lamps

Direction indicators are needed on agricultural trailers and towed equipment that hide the tractor’s own indicators. Fit 1 amber rear indicator on each side, approved as a Category 2 lamp (the approval mark has a 2, 2a or 2b above it).

The indicators should sit near the outer edges and flash in phase with the tractor’s indicators on the same side, from one switch. The driver must be able to tell from the seat that the indicators are working, which in practice means a tell-tale that also covers the trailer’s indicators. When the tractor’s hazard switch is on, the trailer’s indicators should flash too.

Trailer indicators add load to the tractor’s flasher circuit. Older thermal or electronic flasher units sized for the tractor alone may flash too fast or not at all with a trailer connected, and LED lamp boards can cause the opposite problem. See trailer lights not working for the fault-finding steps.

Rear reflectors and reflective markings

Rear reflectors are red, and on trailers they are normally triangular. The approval mark on a triangular trailer reflector includes “III” or “IIIA”, which is the triangular class. Triangular rear reflectors are meant for trailers, so do not fit them to the tractor itself.

Heavier, wider or longer trailers can also need retro-reflective markings and, on oversize combinations, warning signs. The thresholds and exemptions are set in the Land Transport Rules and NZTA Waka Kotahi’s agricultural vehicle guidance, so check the current rules for your trailer rather than relying on overseas figures. Replacement triangles and amber side reflectors are in our vehicle reflectors range.

Side lamps at the front

Side lamps (front position lamps) are worth fitting on any agricultural trailer that is wider than the tractor, and can be required on wide trailers. They are white, face forward, and should sit near the outer edges of the trailer’s front corners. The front corners are the part an oncoming driver is most likely to misjudge, especially when the trailer is wider than the tractor.

New Zealand’s vehicle lighting rules set the colours: in general white to the front and red to the rear, with amber for indicators and side markers, so do not fit red lamps facing forward on the trailer.

Side marker lamps and side reflectors

Side marker lamps can be required on long trailers and long combinations. The length at which they apply, and where they must be fitted, are set in the Land Transport Rules, so check NZTA Waka Kotahi’s agricultural vehicle guidance for your trailer. Approved (for example E-marked) marker lamps are the safe choice.

Many farmers fit marker lamps on both sides of a long trailer, which helps at night on narrow rural roads and at junctions. Side marker lamps are amber. Amber side reflectors spread along the body add a cheap extra layer of visibility. Our side marker lamps suit long bale trailers and low loaders.

Number plate and number plate lighting

Where an agricultural trailer carries a rear registration plate, the plate must be lit at night. A missing or faulty required lamp can mean an infringement fee from Police.

Whether a particular agricultural trailer must be registered, and which plate it displays, depends on the trailer and how it is used. Check with NZTA Waka Kotahi, which handles vehicle registration, if you are unsure. The plate lamp is wired with the tail lamps so the plate lights whenever the side lamps are on. Dust and water ingress are the usual reasons a plate lamp fails, and sealed LED plate lamps are the common replacement.

Lighting boards for towed equipment

Towed equipment without its own lights, such as balers, sprayers, rakes and similar machines, needs lights only if it hides the tractor’s own front or rear lamps or reflectors. In that case a lighting board should be fitted. A lighting board carries the rear lamps, stop lamps, indicators and number plate lighting on a single panel that clips or straps to the back of the implement.

Rear fog lamps and reversing lamps

A rear fog lamp is not on the obligatory list for agricultural trailers. If one is fitted, it must be red and should only be used when fog, snow or similar conditions cut visibility. Switch it off when visibility improves.

Reversing lamps are optional. They must show white and may only be lit while reversing. On a 7-pin 12N connection there is no reversing circuit, so trailer reversing lamps need a 12S or 13-pin connection or a separate feed.

Wide, long and heavy agricultural trailers

Size changes the picture in 4 ways:

1. Beacon: New Zealand rules require an amber warning beacon on agricultural vehicles in a range of road situations, such as oversize or slow-moving operation. A high-sided trailer can block a cab beacon from behind, so a second beacon on the trailer is a sensible addition.
2. Width: agricultural vehicles in New Zealand have their own width provisions, and wider machines and trailers move into oversize categories with extra requirements for warning lamps, signs, travel times and sometimes pilot vehicles. Check NZTA Waka Kotahi’s agricultural vehicle guidance for the categories.
3. Length: long trailers and combinations can need side marker lamps, side reflectors and markings. Check the current length limits and lighting thresholds in the NZTA rules for your combination.
4. Weight: towing limits depend on the tractor, the trailer’s brakes and the coupling. Follow the manufacturer’s ratings and the NZTA rules.

Loads that overhang the back or sides of the trailer need marking. New Zealand rules require projecting loads to be marked so other road users can see them, typically with a flag by day and lamps or reflectors at night, and the exact distances are set in the Land Transport Rules. Check the NZ Road Code or NZTA Waka Kotahi’s guidance on load projections before carrying long or wide loads.

7-pin and 13-pin trailer connectors

The trailer lights connect to the tractor through a 7-pin or 13-pin plug and socket. Many tractors and farm trailers in New Zealand use the 7-pin 12N connector (ISO 1724), which carries left and right indicators, left and right tail lamps, stop lamps, earth and one auxiliary pin that is normally used for the rear fog lamp. The pin layout, cable colours and wiring steps are in our 7-pin trailer plug wiring guide.

The 13-pin connector (ISO 11446) carries all the 12N lighting functions plus reversing lamps, a permanent feed and an ignition feed in one plug. It is standard on cars, vans and pickups, and some farm vehicles and trailers now use it. Some New Zealand utes and trailers use Australian-style flat 7-pin plugs instead, so check which type your tractor and trailer have before buying adapters. A 13-pin to 7-pin adapter connects one to the other for the lighting functions. See 13-pin trailer plug wiring for the pinout and adapters. Some 24V machines use the 24N connector (ISO 1185), which has a different pin layout, so 12V and 24V plugs and lamps should never be mixed.

Roadside checks and common trailer lighting failures

Agricultural trailers have their own treatment under NZTA’s rules, and many do not need a Warrant of Fitness or Certificate of Fitness, but they must be kept roadworthy. Their lights can be checked at the roadside by Police, including the Commercial Vehicle Safety Team. The lamps the trailer is required to carry must be clean and working whenever it is on the road.

The most common failures found on farm trailers are:

• A bad earth at the plug, the lamp board or the trailer chassis, which causes dim, flickering or crossed-over lights.
• Corroded pins in the 7-pin plug or socket, from water, effluent and coastal salt.
• Cable chafed through where it runs along the drawbar or over the headboard.
• Cracked lenses and missing triangular rear reflectors.
• A number plate lamp that has filled with dust or water.
• Indicators that work on the tractor but not on the trailer because of a failed flasher or blown fuse on the trailer circuit.

Using a trailer without its required lamps, or without a required marker lamp, can mean an infringement fee. A defect that makes the combination dangerous can be dealt with more seriously, and an unlit trailer at night is one of the most dangerous things on a rural road.

A pre-season trailer lighting check

A 10-minute check before harvest, silage or effluent season catches most faults before they cause a stop on the road:

1. Connect the trailer and switch on the side lamps. Walk round and check both tail lamps, both front side lamps, any marker lamps and the number plate lamp.
2. Have someone press the brake and check both stop lamps.
3. Run the left indicator, the right indicator and the hazards, and confirm the trailer lamps flash in time with the tractor’s.
4. Check every reflector and reflective marking is present, clean and the right colour: red at the rear, amber at the sides.
5. Open the plug, clean the pins with contact cleaner and a fine brush, and smear the contacts with dielectric grease.
6. Follow the cable from the plug to the lamp boards and replace any section that is chafed, cut or held on with tape.

Frequently asked questions

Does an agricultural trailer need brake lights?

In most cases, yes. In New Zealand, an agricultural trailer that hides the tractor’s rear lamps needs its own stop lamps, along with rear lamps, direction indicators and reflectors; check NZTA Waka Kotahi’s rules for your trailer. The trailer hides the tractor’s stop lamps, so working trailer brake lights matter for everyone behind you.

Does a farm trailer need indicators?

In most cases, yes, wherever the trailer hides the tractor’s indicators. Fit 1 amber Category 2 indicator on each side at the rear, flashing in phase with the tractor. Some trailers used only in daylight can have fewer requirements, so check the NZTA rules.

When does a trailer need side marker lamps or side markings?

Side marker lamps and side reflective markings can be required on long trailers and combinations, and on oversize agricultural vehicles. The exact lengths and exemptions are set in the Land Transport Rules, so check NZTA Waka Kotahi’s agricultural vehicle guidance for your trailer.

What number plate goes on a tractor trailer?

It depends on whether the trailer has to be registered, which varies with the trailer and its use, so check with NZTA Waka Kotahi. Whatever plate is carried, it should be lit at night.

Why do my trailer lights work on one side only?

The usual cause is a poor earth, either at pin 3 of the plug or where a lamp board earths to the trailer frame. A damaged core in the cable, a corroded pin or a blown fuse on the tractor’s trailer circuit can also take out one side. Our trailer fault guide walks through the tests in order.