Room Full of Working 120V Electrical Outlets, Except One Doesn't

Question

I have a room with 5 duplex outlets (including 1 GFCI) and 2 single pole switches on a 20 amp circuit.

One outlet isn't working and measures 0V from hot-neutral, 1V from hot to ground and 1V from neutral to ground (and measures the same voltages when directly touching the wires, rather than just inserting into the receptacle).

The other 4 (including the GFCI) measure the expected ~120V from hot-neutral and ~0V from neutral-ground, but only ~11V from hot-ground (which I take to mean these are not grounded properly?).

Both single pole switches are working just fine, but I did not bother taking voltage readings (though I certainly can if this would help diagnoses).

I have no idea what steps to take in order to address the 0V from hot-neutral outlet -- does anyone have a suggestion?

Answer 1

First, the non-working outlet is likely connected to a wall switch or a junction box, which may have been disconnected or even removed and covered over. Trace the wiring, either with an AC circuit tracer or metal/stud finder to find the junction box.

Second, how are you measuring the voltage hot-ground? A high-impedance multimeter may be picking up AC capacitively coupled from a parallel line, and the ground could be floating. An outlet tester might be better. That said, if the ground is floating, perhaps due to poor connection (or no connection) in a junction box, that is a serious safety issue; trace it as above and fix it.