Check IoH Lighting and Marking Before Spring Fieldwork

Lighting and marking of implements of husbandry (IoH) are valuable safety features when operating on public roads.  New regulations were effective November 1, 2015. Many pieces of farm machinery have already been manufactured with the lighting and marking requirements that are now reflected in Wisconsin laws.

If you are involved in a roadway crash, you’re vehicle will be reviewed for proper lighting and marking for the vehicle.  IoH operators are also required to follow rules of road same as other motorist including warning other motorists of your intent to turn and following road signs.  If you employee tractor and machinery operators, these requirements are important to include in your annual tractor and machinery operator training too. Your daily checklist should include that lights and lamps are working and clean as well as checking that warning devices are cleaned.

A color photo of a farm tractor towing a piece of tillage equipment

There have been a number of changes to laws related to Implements of Husbandry operating on Wisconsin highways. Before spring fieldwork check that you’re equipment meets the lighting and marking requirements.

Here’s a few key reminders as you get your Implements of Husbandry ready for fieldwork this spring.

Hours of Darkness

Hours of Darkness is the period of time from one-half hour after sunset to one-half hour before sunrise and all other times when there is not sufficient natural light to render clearly visible to any person or vehicle upon a highway at a distance of 500 feet.  s. 340.01(23) Wis. Stats.

  • For non-wide IoH, lighting and marking requirements are required during hours of darkness.
  • Wide IoH laws require lights or lamps to be activated at all times vehicle (s) are operated on the highway or public road.
  • Slow Moving Vehicle (SMV) emblems are required at all times.
  • Wisconsin law does not define hours of daylight.
  • s. 340.01(23) Wis. Stats.

 Marking Requirements

Slow Moving Vehicle Emblem
  • A slow-moving vehicle (SMV) emblem is a required marking on any type of IoH, including animal drawn, that usually travels at speeds less than 25 mph.
  • It is to be displayed at all times on the most visible rear area of the vehicle or combination of vehicles.  If a SMV emblem on a power unit is visible from rear and in compliance, then the towed units are not required to have an SMV emblem.  It is allowable for two or three vehicle combinations to have more than one SMV emblem.
  • These emblems should be mounted pointing upward perpendicular to route of travel, with the lower edge 2 to 6 feet off the ground, and either centered or as near to the left of center of the equipment as practical.
  • SMV emblems must be bright and clean, and should be replaced if faded.
  • s. 347.245 Wis. Stats.

 Lighting Requirements for vehicles not meeting the wide IoH definition

Lights or lamps in the table below must be activated when operating on the road or parked in the right-of-way during hours of darkness.

Self-Propelled IoH including tractors
  • 2 white headlights·
  • At least 1 red tail lights If purchased with 2 red tail lights both must be working.
  • Tail lights are to be mounted 20-72 inches off the ground.·
  • Work lights are prohibited for use on road or when parked in right-of-way.
Towed IoH
  • 2 red tail lights or 2 red reflectors on the rear.(If manufactured before 1984, these IoHs are allowed to have only 1 lamp or 2 red reflectors on the rear.)
  • Towed IoH that is more than 4 feet wide to the left side of the hitch must have an amber reflector at the widest point on the left side facing forward to warn on-coming traffic.
3- vehicle trains
  • 1 red light or red or amber reflector must be located on the left and right side of every vehicle in the train visible from a minimal distance of 500 feet.
Animal-drawn vehicle 
  • 1 white lamp visible from the front
  • 2 red lamps or lanterns visible from the rear marking the width of the vehicle visible for 500 feet and mounted to indicate extreme width of the vehicle.

Wide IoH

In addition to the current requirements for lighting and marking the following requirements apply based on the width of the IoH:

Self-propelled including farm tractors in excess of 12 feet
  • Must be equipped with a 360−degree yellow or amber rotating strobe or beacon light, mounted at the highest practicable point, OR
  • 2 flashing amber lights visible to the front and rear
  • Activated at any time when operated on the road or parked in the right-of-way

Note: Any attachment to a self-propelled IoH or farm tractor is included in the vehicle’s width.

Wide IoH, in excess of 15 feet or that extend over the center of the roadway into a lane intended for the opposite direction of travel.

Option A: At all times when operating on highway

  • At least 2 amber flashing warning lamps, visible from both the front and rear. Must be mounted, as nearly as practicable, to indicate the extreme width but not more than 16 inches from the lateral extremities.
  • Red retroreflective material, visible to the rear and mounted within 25 inches of the extreme left and extreme right of the IoH, spaced as evenly as practicable.
  • At least 2 strips of yellow retroreflective material1 visible to the front.  On left and right sides of IoH, the outer edge of this material shall be mounted within 16 inches of the extreme left and extreme right of the IoH.
  • At least 2 red tail lamps mounted to the rear of the IoH, or as close to the rear as practicable. Not required to be wired to light when headlamps or other lamps light.

Option B: At times other than darkness, a wide IoH, may be operated on highway if all of the following apply:

  • Is accompanied by an escort vehicle operating with hazard lights activated.
  • 2 orange or red flags, not less than 12 inches square, are attached to the rear of the wide IOH, or as close to the rear as practicable to mark extreme left and extreme right of IoH.

In addition, IoH wider than 22 feet traveling greater than .5 mile, must have an escort with hazard lights activated:

  • When operated on highway with one lane of travel in each direction escort vehicle shall operate ahead of wide IoH.
  • When operated on a highway with more than one lane for travel in each direction or on a 3-lane highway, escort vehicle shall operate behind wide IoH.


IoH and being transported by a 2 vehicle combination trailer or semi-trailer need to follow these lighting and marking requirements:

  • 2 flashing amber warning lights activated while IoH is being transported, visible to the front and rear, and mounted to indicate the extreme width while being transported.
  • self-propelled IoH and farm tractors exceeding 12 feet in width, a yellow or amber rotating strobe or beacon light or2 flashing amber warning lights visible to front and rear must be activated.

For additional information on agricultural vehicles on the road, see

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