here's the set up...
i've been running a small room AC and woke up with it not working. a few other outlets are not working.

so here's what i checked...
breakers are all good..flipped them all on and off just to make sure.
the wiring are not not stubbed in...they are all looped around the outlets.
nothing is daisy chained if it's more than one wire there's a wire nut and a separate wire going to the outlet.
the outlet is not burnt or smell of anything burned in the area.
the house is wired with AC cable dated 1930s...some newer AC cable were installed in the 90s.
no changes were made to the electrical for the last 6-7 months...window AC has been running for 3-4 months now. changed a few outlets but checked all the wiring and they look solid.
all wiring are copper...no alum stuff.
took cover off panel and everything is tight to the bar.
no GFCI

volt meter findings:
black to ground reads 120v...(more or less).
white to ground reads about 30ish to 40 volts.
both white and black legs together reads in the 80s volts.

do i have a burnt out neutral wire somewhere in the wall?

let me know what you think the issue is..thanks!

 

It certainly sounds like a loose neutral. The heavy load from the AC has caused a connection to fail.

All the connections should be able to be checked in accessible junction boxes.

 

What you describe does sound like a problem in the neutral. While it could be somewhere inside a wall, it seems more likely that it would be in one of the neutral splices between the receptacle for the air conditioner and the panel.

I would start by opening each of those neutral splices, making sure that the bare conductor on each wire is long enough to make a good connection and that the conductor is in good condition, and then making the splice back up, well-twisted. I would also replace any wire nut that did not look essentially new. It won't hurt to double-check the splices on the hot wires while you're at it, but you do have 120V at the receptacle so that's not the source of the problem.

 

another snag is finding out which outlet this circuit serves. the wall the outlet the AC was plugged into shares the common wall with another bedroom. that outlet is dead also...but i can't determine what else is on this leg (breaker)...thanks to the lazy guy that installed the box that barely labeled anything. in his defense each breaker services multiple areas. like one would service half of one bedroom, half of another bedroom, and then lights in the living room one level down...yeah it's a little complicated.

sooooo any idea how i should go about looking for this loose connector? i hate to be sitting here and undoing all the wiring in every outlet/switch/box/etc. safe to assume the problem is between the last good outlet/run and the first bad outlet/run..right?

the other thing...is there a chance the wire might be burnt out in the wall somewhere? if so what the heck do i do? the walls are wood lath plaster...don't really want to do a demo job if i don't have to.

happy labor day...i get to labor with wiring...

 

Yes: See Troubleshooting a dead receptacle or light + Basic Terminology.

 

Assuming you are having a problem with the original wiring, you have to understand that in the 30s there were not many appliances available (maybe radios and fans) and that the electrical design at that time may have covered numerous lights and outlets in multiple rooms. I have seen many smaller homes built in the 30s and early 40s wired with BX cable that originally had only 2 circuits in the entire house, such as East lights/outlets and West lights/outlets, and those were just 15 amp circuits! Following the advice given will probably help you find your problem, but once the problem is found and repaired, I'd recommend you not plug your window a-c back into the existing circuit that was never intended for such loads. You need a new circuit with new modern wiring for these bigger loads.

Yes, there is a chance, although slight, that the wiring could be interrupted inside a wall between boxes, but it isn't likely. The chances of this increase, however, if you have a 15 amp circuit protected by a 20 or 30 amp breaker or fuse that was installed for the many loads you now have.