These days the most popular addition to any vehicle is supplemental lighting. This is usually attached by the owner of the vehicle, in an attempt to prettify it. This trend has been increasing in popularity ever since the introduction of LED lights (Light Emitting Diode) which allows for an extended life on ordinary lighting and less amperage draw from the vehicle's charging system -- likely the battery. The voltage in which these LED lights use are the same, irrespective of where they are placed, in that they will use any conventional 12-volt lighting system. One caveat is that some countries restrict the usage of particular lights on vehicles -- in particular, specific colours, such as a dark blue would commonly indicate an emergency vehicle, and therefore these are usually forbidden by law, and will be confiscated by the police if spotted.
Once you have determined the location for your supplemental lighting, you need to apply 3/4-inch masking tape along the path for which you have chosen -- if you have chosen to install more than one light, otherwise these can be done individually. Determine the spacing of the lights along the previously applied masking tape, and mark these as necessary with a black pen. This will give you a rough guide as to how the lights will be positioned and spaced.
Use the light's mounting gasket as a guide, mark the holes for which will be drilled to install the LED lights to your vehicle. However, if no gasket is actually provided with your supplemental lighting, then this is something in which you're going to need to do yourself -- by tracing their outlines onto the paper. This will ensure that when the lights are attached to the vehicle, they are accurate, and no mishaps will occur -- or at least, a reduced likeliness for such a mishap to occur.
Once all the templates are in place, from the masking tape to where the holes are going to be drilled, and you are satisfied with where the lights are going to be, it's time to begin drilling the holes for each light. The general rule here is that you'll drill two holes for the mounting screws, and one for the light's wire. After doing so, you will want to remove the tape, as this would look entirely inadequate on your vehicle. Aim to do this before you attach the lights, since removing it afterwards would be infinitely more difficult. Insert the wire and attach all the screws into the previously drilled holes. Your lights will now be mounted to your semi-truck.
Using such tools as pliers and line splicers, connect each light's wire to the inline 12-gauge wire which will be required for powering your new lighting system. Be sure to secure each wire to the vehicle's cab with wire ties. This will prevent the wire from dangling unnecessary from the vehicle, with the potentiality of being caught on any objects along your journey, which will completely ruin your vehicle's overall appearance, and busy all your hard work in 6 feet of dirt.
After this, you will need to connect the single 12-gauge power wire to the light wire source in the vehicle wiring harness. There is a simple way of doing this, in that if you locate one of the factory mounted lights already installed on your semi-truck, preferably the one closest to your new supplemental lighting system, and then splice into its power source. The lights will then work off the dashboard mounted factory light switch, which is nice and convenient for turning them on and off with ease.
One should always choose the LED lighting systems, since these are the best by far, and as they are easy to install, and last for what seems like forever, it's quite convenient to add many lights to your semi-truck. Once you have installed as many LED lights as to make your heart content, you can stand back and admire your own Las Vegas on 18 wheels!