To twist two wires together you first need to strip the insulation off the wires. Just make sure that the ground you connect it too has sufficient current capacity but nearly every ground wire in the vehicle will be able to carry the current required for two lights.

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Can you connect two ground wires together. Thank you for sharing your electrical question with us. The other flaw is you insist on using a 30 amp breaker to protect a 15 or 20 amp duplex. In all the methods described except for the crimping method and the alligator clip method you will need to start with the wires twisted together. Yes you can repair the ground wire by spicing the two pieces of wire together using a small twist on wire connector. To use the wire nut simply insert the tips of both wires and turn the wire nut in a clockwise direction until tight. Using one hole for multiple conductors is only allowed if the terminal is rated for more than one wireanother ground bus bar can be added.
Make sure the two ends of wire have the insulation removed about a half inch or more so the two pieces of wire may be joined together to complete the splice. Next hold the wires side by side and twist them together with your thumb and forefinger. Step 5 finish mounting your light fixture according to the manufacturers instructions. Connecting the ground wires is usually the first thing joe does when he wires up an electrical outlet knowing how to use the crimping caps is a good way to connect up all the ground wires. If your light fixture has its own green ground wire you will need to connect the two ground wires using a wire nut. Since the main breaker should reside in this panel the neutrals and grounds do get connected together here.
There is no problem with joining the two grounds together.