Lahars are a specific kind of mudflow made up of volcanic debris. They can form in a number of situations: when small slope collapses gather water on their way down a volcano, through rapid melting of snow and ice during an eruption, from heavy rainfall on loose volcanic debris, when a volcano erupts through a crater lake, or when a crater lake drains because of overflow or wall collapse.
A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. The heart of a relay is an electromagnet (a coil of wire that becomes a temporary magnet when electricity flows through it).
Whenever wiring off road lights, it's important to add a relay to the wiring. Failure to do so would cause excessive heat in the wiring and switch and create a risk of fire. This is caused by the amount of power being drawn by the high output lights or accessories. relay works by using a switch to run 12 volts to the relay. The relay acts as an electrical switch that activates and draws power straight from a good fused battery connection and sends it to the lights or accessory. The power actually going to the switch never gets routed to the lights.