So you've just had a new arena installed, and as the hours of daylight ebb away you realize that yes, some lights would be nice. The cheapest, easiest solution for an outdoor arena is to mount a few directional floodlights on poles around the arena. This solution should provide sufficient lighting to allow some light flat riding to occur after dark.
Even outdoor lighting
If, however, jumping or barrel racing or some other more demanding activity will take place after dark, a better lighting solution is essential. Shadows and uneven lighting can create serious hazards around jumps and other obstacles. It is much more difficult to light an outdoor arena evenly than an indoor arena. In an indoor arena the lights can be mounted evenly across the ceiling and thus ensure all areas of the riding space are well-lit.
For indoor arenas, consider installing waterproof light fixtures. Yes, there is a roof, but what about the sprinkler system
In an outdoor arena, the lights can only be mounted along the edges of the ring. In order to provide good, even coverage of the space, very tall poles and large floodlights need to be installed. Metal halide light fixtures are the industry standard today. Metal halide lights render colors accurately and produce very bright lighting. They can often be installed on existing wooden poles using the currently existing electrical lighting system.
For very large or upscale commercial outdoor arenas, steel or fiberglass poles are superior to wood poles. To light a large arena successfully, it is necessary to hang the lights higher, and thus a steel pole is preferable. Steel poles are also more durable than wooden poles.
For indoor arenas, outdoor metal halide lights will work. However, currently high bay fluorescent lights are the preferred solution for indoor arenas. They use much less energy than metal halides, and unlike the older types of fluorescent lights, they work just fine in very cold temperatures.
For indoor arenas, consider installing waterproof light fixtures. Yes, there is a roof, but what about the sprinkler system? The environment inside an indoor horse arena can be as harsh as the out-of-doors, what with dust, humidity, sprinklers, and corrosive fumes from horse waste. Waterproof light fixtures will last much longer. And they can be cleaned off more easily.