Yes you could so long as the relay is rated above the total current draw of all three lights and the power feed wiring is correctly sized and fused. Take the wattage of each light x number of lights = total watts. Take the total watts / by the battery voltage = total amperage.

Example:
100 watts x 3 = 300. 300/12 = 25 amps. Use a relay rated at 40 amps. Fuse should be at least 30 amps. Wire size minimal 12 ga from battery to relay and beyond to where you split to the individual leads to the lights. From there you could down size to 14 or 16 ga wire

 

Thanks.

This is what I have. 3-55w bulbs, a 40 amp relay, and 18 gauge wiring kit from hella that comes with 15 amp fuses. So with only 13.75 amps I should be alright with the 18 gauge wire and the 15 amp fuses?

I found this.
Wire Gauge Amps Ratings for 12 volt Automotive Systems

Thanks guys. Just needed some confirmation. I don't wanna pull a l2en.

 

As a general rule of thumb you want the fuse to have at least a 5amp rating above the circuits nominal operating current. Remember the calculations are based on a perfect set of conditions. With manufacturing tolerances what they are the actual wattage could be plus or minus by several watts for each bulb. Also when a bulb blows there could be a momentary spike so I’d recommend a 20amp fuse in its place. I’d also recommend running at least 16ga wire to play it safe.