I always connect the ground wire to the box. However, if there is no real ground wire running back to the panel it really does you no good. The NEC requires that you rewire the circuit with the proper conductors.
Remember that the ground is for your protection. Without a proper ground, you run the risk of injury or death if the fixture wiring fails.
If you're asking whether you have to connect the fixture ground to the house ground, you do. The idea is to connect any exposed portion of a metal fixture to ground, keeping anything you would be able to touch from having a hazardous potential on it. The way to do this is to connect the fixture ground (which is connected to the metal chassis) to the building ground (which comes from your electrical panel).
Connect the ground wire to the metal box.
Yes. Connect Black to Black, White to White and bare ground wires together.
If you mean 2 bare copper wires those are the ground wires. Tie them together and then connect the light fixture ground wire which will be green or bare copper to those ground wires.
Very often the ground wire in the fixture is ignored, or just connected to the box, if there isn't a conductor to connect to. This, however, is a code violation as any fixture with a ground wire is required to have it properly connected to an equipment grounding conductor back to the panel. This is for YOUR SAFETY. Technically you should rewire the circuit with the proper conductors. It is BAD PRACTICE to connect the ground wire to the neutral or white wire because this could create a hazard of its own.
If there is a red wire in the fixture box it sounds like the fixture is three way switched. The travelers are coming from one of the two switches and the cable is going to the second switch.See related links below.
A ground wire is a typically uninsulated copper wire. The intent is to connect the wire to an electrical appliance or fixture to provide electricity a path to ground in the event of a short, thus preventing electrocution.
If you are referring to a porcelain or plastic ceiling light fixture most do not have a place to connect the ground wire. You cannot ground these type fixtures. Just connect the ground wire to the mounting crossbar and forget about connecting it to the light itself. It is on the ceiling and will never be touched unless you change the bulb and then you will have the switch in the off position. It is perfectly safe.
The fixture box should have a ground screw on the bottom of the box. Sometimes you have to move other wires out of the way to see it. Just reconnect the fixture ground wire to this screw.
Connect them in parallel. The black wire from the ballast to the black line wire. The white wire from the ballast to the line neutral. Connect the ground wire to the ground screw which is located in the body of the fixture. Grounding of the fixtures is essential.
Don't worry about it some fixtures have no ground terminals. just shove the groung wire to the back of the box. Correction, if the fixture is metal and it shorts out, the metal surrounding the fixture could become electrified. That's why fixtures today are normally grounded to their mounting plates and then the lead is attached to the incoming romex. In the past, attaching these plates to metal boxes (either grounded by an incoming wire or grounded to the BX cable) eliminated the need for a ground wire. If the hot wire hit or shorted to the fixture, it would blow a fuse or circuit breaker. Many electrocutions and fires later, the folks at Underwriters realized that even that method of grounding wasn't sufficent (the old aluminum boxes and bx cables were crappy conductors. Solution; (and I practice what I preach because I remodel many old homes) get a little creative and spend the extra time to wrap a little ground wire to a mounting screw, or piece of metal, on the mounting plate of the fixture and then attach it to your incoming romex ground. On an old fixture, it could mean the difference between a fire and a tripped circuit breaker. If you have any metal boxes, old or new, ground to those too. <><><> Connect a pigtail to the metal canopy, and use a wire nut to connect the safety ground to it.
There should be two wires in the box, black and white and possibly a bare one depending on the age of the wiring in the house. The fixture has two screws on the base. One wire goes on each screw. If there are short wires on the fixture, black to black and white to white. If there is a bare ground wire in the house box, it attaches to the body of the fixture. If there is no ground screw on the fixture, do not worry about it.