If the wiring is correct turn the power off and install the device in the outlet box. Carefully fold the wires to fit into the box and push the device with your palm until it sits flat and is aligned with the mounting holes. Drive the mounting strap screws and shift the replacement of the device left or right as necessary to square it in the box as you tighten them down. Install the cover plate, turn the circuit back on and test the device again.
If you want to use a source with the maximum wires already present, it may be possible to split the source before it enters the box. Cut access to the wiring through the wall material and add a junction box to splice the new outlet into the circuit. Cover the box with a blank plate to protect the splice.
Short for ampere, a unit of measure for current or the volume of electricity running through a circuit. The amp rating for a device or cable determines the amount of current it can safely handle. Typical household circuits begin at 15 amps and go up to 50 or 60 amps.
In this example a new wall receptacle can be installed using an existing receptacle in an adjacent room. This can often be the easiest and most likely solution to access a source for a new receptacle or a switch to a new light fixture. Set the new outlet box in the same wall space as the existing one to simplify running the cable.