My house was inspected and they said I need a 4 wire feed to my electrical box. I have 2 110 lines and the str

Answer 1

If your meter is more then 10 feet from your main panel you need to have a main disconnect at the meter and run a 4 wire wire from the meter to panel because the panel is now considered a sub panel

Answer 2

If this is a sub-panel in a building that is detached from the building that has the service, then yes, you need four wires: two hot, one neutral (grounded conductor) and one equipment (green or bare) ground.

You need an approvred driven ground system at the sub-panel, bonded to the panel neutral bar. The green bonding screw must be removed from the neutral bus, and a separate busbar must be bolted to the steel cabinet, and the green ground landed on it.

Equipment grounds (green and bare wire) and grounded conductors (white wires) don't got to the same place in a detached service panel.

There IS a code allowed 3-wire arrangement for that same thing if there are no electrically conductive paths between the building with the service and the outbuilding (telephone, water, etc.) but most jurisdictions today only approve the 4-wire feed.

Answer 3

I built a barn and installed a sub-panel for power in the barn. Since I used the main panel of my house for the power feed I had to run 4 wires to the barn. Two 110 lines, one Ground and one Common. The Ground wire also had to be tied into an 8' ground rod. The way that the ground is tied together(bonded) may be different in your area.