Nine lamps and six reflectors are the minimum required by law to be installed and functional on your trailer. If that trailer is not a small one, the number grows rapidly to stay in compliance depending on its length and width. Not just any lamp or reflector will do either, they all must be the right device for the right place and comply with standards.
Manufacturers of trailers must comply with the requirements set out in the federal Motor Vehicle Safety Act and Regulations. Should you choose to build your own trailer, you will have to comply with the British Columbia Motor Vehicle Act Regulations. Ultimately, both hold the builder to the same set of standards and the police enforce them after construction is completed and the trailers are in use on our highways.
The minimum consists of yellow side marker lights and reflectors at each side of the front, red side marker lamps and reflectors at each side of the rear, red stop lamps, tail lamps and reflectors at both sides facing the rear and finally a white license plate lamp. All of these devices are marked according to standards identifying them as acceptable for their purpose and may or may not be combined in the same unit.
If your trailer happens to be more than 2.05 meters in width or 9.1 meters in length, additional lamps will be required. These generally consist of intermediate side marker lamps, clearance lamps and identification lamps, depending on which dimensions are exceeded.
The days of not requiring brake lamps on a trailer when the brake lamps of the towing vehicle are visible are long past. Reference Links