I have hall light that works sometimes and I can't figure out why. The circuit that powers the light has 110 voltage on all the outlet boxes all the way up to the light switch, but very low voltage (barely registers at the switch). A few weeks ago it worked fine, it has two switches that control the light one at the bottom of the stairs and one at the top. Both of them worked perfectly fine a few weeks ago. I checked the connection at the fuse box and wires are tight and attached correctly. The outlet box right before the wiring goes onto the switch has adequate power. I was told by a friend of mine that knows more about electrical wiring than I do that there is some kind of ground fault probably that is draining the power, but that doesn't make sense to me. The device immediately preceding the switch (the outlet) has power so I don't understand how in a matter of 5 feet or so the wiring is grounding out. I have done nothing to the wall that would have damaged the wiring. At least I have assumed it has to be between the outlet and the switch that the power is being lost.

Are the outlets wired using the screws or stab slots?

If using stab slots,move to screws. Over time slots loosen up and do not make good contact.

Chcuck

You more than likely have a loose or open Neutral (white) connection.

At the light outlet box, can you describe the connections, please.

Also, what are you using to measure the voltage at the various points?

Normally here in the U.S.A. the voltages are 120 and 240. 110, went away years ago.

If you are using a VOM, find the power supply cable for the light fixture. You should have 120 Vac between Black and White. If you do find 120 Vac, then you need to start looking at the switches

Since switches carry only the hot leg (Neutral is not used on a switch) unless it is a specialty switch. What you are looking for is tight connections under the screw terminals. You can also hook the meter up to the bottom (common) terminal (darker than the other two terminals) and one of the travelers. If there is zero (0) volts, change the position of the switch handle. If there is 120 Vac, change the position of the switch handle and you should now see zero (0) volts.

Do the same for the other traveler. Also the other switch.

Once that is done, let me know what results you get.

OK, I opened switch at the top of the stairs and checked the wiring and voltage. When the switch is in the down position the circuit has 120 volts, when it is in the up position it barely registers. The switch uses screws to attach the wires and they are all tight and properly positioned under the screws.

You have a 3 way switch... at the lower switch in the hall... remove the faceplate of the switch and pull the switch from the box. Verify that the N pigtail is tight... then note the wire colors on the 3 mounting screws of the switch. Depending on when it was wired and installed... you might have 14-3 (Black, Red, White, and a Bare Ground(which isn't counted). When you look at the 3Way switch the screw terminals will be arranged as follows:

Screw terminal #1 is your common (black/copper colored screw) it will be alone(nothing across from it) this is either your HOT IN(black wire) or Switched HOT(black wire) to the fixture. It might even have a white wire with a black tracer if power is from the fixture box.

The two other screw terminals (Traveler & Switched) will be directly across from each other one should have a black wire landed and the other side should have a Red wire landed. These two wires(Black & Red) are in the same cable running back to the other 3Way and landed on the same screw terminals.

If the White wire from the above cable has a black tracer than it's the swiched Hot from the upstairs 3way and it's going to be on a wire nut connected to the black wire to the fixture.

The other possibility is Hot Wire is via the ceiling fixture box. As mentioned above, if wired correctly the white wire with the black tracer will be landed on the common screw terminal. If you have a problem with this config... you'll have to remove the fixture to verify that all of the connections are correct and tight. But the 3Ways would still work as described above.

If the white wire doesn't have a black tracer then it should be pigtailed to the other N's in that box. If that's the case, then the upstairs 3way is wired to the hall fixture. No matter the config the Red and Black between the (2) 3 ways will be wired the same. And the common screw terminal will have a black wire going to the fixture.

Be sure to verify that all of the pigtails are twisted tight. Wires need to be properly twisted(3 good twists) before being protected by a wire nut.

If you have any questions repost... good luck!

If you are measuring Volts at the 2nd 3Way... you should be measuring it on either the Traveler or Switched terminals(Red or Back wires across from each other). If you're measuring the voltage across the black wire on the common terminal that might explain your "Floating Voltage".