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relay or fuse

Discussion in 'Truck & Equipment Repair' started by chas4x4, Dec 15, 2005.

  1. chas4x4

    chas4x4 Senior Member
    Messages: 101

    I am terrible at wiring is there a difference if so where should each be used?
  2. calhoun

    calhoun Senior Member
    Messages: 165

    A fuse is installed in a circuit to protect the wiring from excessive current draw. For example a 12gage wire shouldn't carry more than say 20amps. If it carries more it could overheat and possibly start a fire. A 20amp fuse will "burn out" stopping the current. If a fuse blows it means there is a problem somewhere in that circuit.
    A relay is a switch controlled by a switch. It is used to turn on and off a high current circuit but uses low current. For example a plow. The pump draws lots of current. If you tried to wire it directly to a switch you would need to run huge cables to a large switch to carry the current. Instead you can connect the high amp cables to a relay then use small wires and a small switch to just turn on and off a relay. The relay then connects the high current circuit.
  3. chas4x4

    chas4x4 Senior Member
    Messages: 101

    fuse or relay

    Thanks I under stand now what they are used for.