i want to install a new light in a old house.the problem is that there are three black wires coming out of he ceilng.the old light fixture has two black wires. two ceiling wires are connected to one fixture wire and the other ceiling wire i connected to he other fixture wire.i dont know which is the hot wire and which is the comon wire.also the new light has a ground wire ,2 blue wires and 2 white wires but, there is no ground wire coming out of the box. please help
You'll need a multi-meter to test which wire is neutral and which is hot. Technically you don't need to use the ground wire (green), but it would be a good idea for safety to run one from the box to the nearest ground (copper cold water pipe or the fuse panel). Sounds like your fixture has two light sockets? If so, you probably connect the 2 blue wires to the hot wire and the two white to neutral.
a wire is a wire is a wire! the coatings were only put on to keep the continuity in sync. if you have all these blk wires, 2 go into 1 and connected to the lite and the other is connected to the lite, and there is no gnd wire. the 2 are running thru to another lite along the way as they did in those days. don't disconnect them, keep them together and call that your power/red or blk, the single coming down to the lite is the common/white...get tape and mark them so. electrical tape comes in colors. now you won't have that prob in the future. as for the gnd, you should have a metal box, just screw to that. at last resort if you have an attic, run a grn/gnd wire from a water pipe of someplace that will ground and wire nut it off. any Q shoot me an email...
First find a ground. Either copper water line or a wireyou know is grounded. You can put a light bulb in a series so you touch it to the hot wire on your ceiling the light comes on. I would just run the ground wire are up to the ceiling and tap it quickly on each individual ceiling wire. The ones that make a spark are hot wires. Good luck .
A lot of the older homes only used two wires, a hot and a neutral. You need a tester to find which is the hot wire and connect the two blue wires to that wire and the two white wires to the neutral wire. Be sure to turn off the power when you are making the connections. If the ceiling box is not grounded there is nothing to connect the ground wire to. It is important to identify the hot wire as it connects to the wires that go to the center connection of the lamp socket and the neutral connects to the metal screw in part of the bulb. This will reduce the chances of getting shocked when changing a bulb.
Seems to me you are dealing with an old knob and tube wiring system, not complicated. You probable have three cotton coated wires in the ceiling box, they used to be coded and now they're tarnished. Two of the wires are common or neutral and one live being fed from the switch. When you removed the old fixture two wires were connected to one side of the light fixture these are the common wires and one wire was connected to the other side of the fixture this is the live wire from switch. If you can't remember which was which, simply get a tick tracer this device senses a live wire and with the power off verify that you have no live in the ceiling, with power on try again, if you find one power it's as I have said and the remaining wires are common, if not call an electrician they won't charge that much to hang a light fixture and you'll have peace of mind. Good luck.
