I want to install a new light in my soffit at the corner of the house to help light the back yard. The one light on the porch doesn't do a good job.
Is it acceptable to pull a new cable from the existing light box for the porch light up through the wall and then run it down to the other side of the house through the soffit in the gap between the roof trusses and wall? Do I need to use an outside rated metal box mounted to the soffit or can I use one of the plastic flush mounted boxes that you cut a hole in the soffit and it installs with wings that pop out on the sides to hold it in place. The house is cedar sided if it makes a difference.
Yes. You can fish the cable to the new light from the old light. You can use a regular recessed box or a surface mount weather proof box for the fixture. I would use an octagon steel box and secure it to the roof rafter. This will give you a good solid box support. Then use an outdoor fixture with gasket.
To get the lights aimed properly for the area you want lit you may have to build a little wooden wedge block to pitch the box slightly. Even with the ball joints and aiming adjustments they sometimes won't throw light where you want them to.