household electricity riddle

[Pete M]

I was trying to rewire the outlet in my bathroom so that it's constant hot instead of switched hot. then I had an even better idea and figured I'd just run a new wire to the bathroom so it had its own breaker (house was built in the late 40s and so most of the house was originally on the same fuse and over the last 34 years my dad and now I have slowly separated out items like the upstairs, the garage, the microwave, fridge, etc and long ago had the incoming service/box upgraded). by now the old breaker location is down to powering the bathroom and some random lights/outlets around the house and I figured this was a prime opportunity to update again since running wires in the house is next to impossible and the bathroom gives us unique access due to the ginormous plumbing holes. but my readings aren't making sense to me.

 

 

this is what I know so far...

 

So I've got 2 wires coming in to the bathroom, 2 wires going out (on the opposite wall as the incoming) and 3 wires running between them (for switching the light and letting power go through). far as I can tell, those 3 wires are not connected to anything else. of the 2 wires coming in, one gives 90 volts to ground :hmm: , the other 110. I do not get 220 or continuity (breaker shut off of course) between the 2. of the 2 wires going out, one allows the rest of the lights on that breaker to work, the other, well, I'm not certain what it does since nothing changes if it's connected to anything or to nothing at all.

 

If I connect the 90 volt incoming wire to the important outgoing wire, the rest of the lights on the circuit work fine. if I connect the incoming 110 wire, the breaker blows. If I attach the brand new hot wire to the outgoing wire, the breaker blows.

 

and just when I was about to give up and return all the wiring to its former state, I noticed that the kitchen light (last thing in the kitchen that isn't on an independent breaker since it's wiring is buried in the ceiling) and its plug are doing funny things. the light switch has a built in constant hot outlet. the outlet is hot when the breaker is on, dead when the breaker is tripped. the light on the other hand works only when the breaker is on and that outgoing wire in the bathroom is connected to that incoming 90 volt wire.

 

in my head these things have got to be related. :dunno: I haven't mapped out the entire house so this may not yet be solvable with the data available, I'm just looking for ideas and also writing it all down helps me keep it straight.

 

I'm currently working on getting that stupid stuck light fixture in the kitchen down so I can access the wires.

 

[kastein]

Is it all knob and tube? I hate that crap... got rid of all of it on my parent's first floor except a couple light fixtures and stuff like that that you mentioned, ran all new Romex and metal boxes.

 

Without trying to interpret the "what works when" and "breaker blows" bits of info, my bet is that the 90 volt line is either a hot wire going through a lousy connection, or the cold wire from the kitchen lamp (which is now floating since you disconnected it from the cold line to the panel.) The extra resistance makes it measure as less than 110.

[dasbulliwagen]

A lot of early light systems were what you call switch legged, that means the hot wires come into the light first, and then have a switch leg run down the wall to a switch, which means you have hot at all times in the light, and you need to shut off the breaker to touch any of the light wires. Newer houses have the hot come in at the switch, and then to the light... the old way saves a little wire as you don't have 2 runs going into the switch box. If your getting 90 volts on one leg, then you may be reading it after a resistance, such as a light bulb.... depends on how it was wired though.. definitely needs straightened out! You might start by shuting off the breaker to the light, unhook all wires at the light and in the bathroom, then turn the breaker on, and find out exactly where the power actually comes in at, and work from there. Good luck, let us know what you find

[jimoshel]

:agree:

Remove every wire involved. See which ones are hot and which are neutral, ground. There is no way you should be getting 90V. To get 90V you have a hot wire going thru a load that is not properly terminated or you have a neutral wire that is not grounded.Then rewire everything as if you were starting from scratch. It's a lot easier to start fresh than to figure out the old. I recently bought and rewired a house that was built back in the 30's. NOT FUN.

[boman40]

Your print sucks, So I reread and reread your problem. What I think is this is just a switch box with three Hots and one switch leg, or load, light. My questions are, Where are you getting/ testing the ground from? What are the wire colors? All blacks, or do you have a light brown / white wires.

If you have two hots, and they do not read 230 volts between them, they are probably the same phase. First rack out the breakers one at a time and check each hot wire to see if they are on the same breaker or on different Breakers.

If they are on two different breakers, Then this box was used as a junction box / switch box and you have different circuits in it. One for a light and one for something else, ???. You will need to find out what the other wires go to.

With knob and tube a lot of times the circuits where looped, back feed, or tied together since they only had one fuse for the whole house. This was one of main reasons for house fires.

I take it that this house was rewired at some point, since you do have breakers / breaker panel. Sounds like your electrician

did not upgrade all the wiring.

Since this is in your bathroom, I would find out where all the wires come from and go. Unhook them from the power source and start over with new Romex wires. I know this is going to be a pain but better safe them sorry latter. Don't for get that the bath room needs to be on a GFI circuit. Hope this helps.

[jpnjim]

1) Voltmeters are not the best tool to read voltage.

sounds stupid, I know, but with transient voltages,bad grounds, bad neutrals, etc etc, volt meters only complicate things by giving a very precise reading of a surface charge that's not even really there.

 

That's why an electricians set of "Wiggys" is a volt meter with a solenoid inside it to actually draw a load as it tests.

The load is important because it actually dissipates the surface charge (makes it go away).

 

If you connect the '90v wire' (I'm guessing it's the neutral) to ground with the wiggys, and still get 90v, you have a more serious issue than connecting a voltmeter and reading a surface charge of 90v.

 

2) Electrical stuff can get confusing as the issue gets more complicated.

Always go back to the basics:

 

Find out what is your line in.

 

Find out where/what your loads are.

 

Popping a breaker is not the way to diagnose something.

If doing something trips the breaker, STOP doing that.

 

Most of the time a breaker will trip like it should,

but SOMETIMES it will blow right up in your face.

Yep, breakers blow up every day, might even blow up after tripping like it should 10 times in a row.

Especially when it's a dead short tripping it.

 

 

3) Honestly Pete, the guys most likely to be killed by electricity are electricians, who do the work every day.

If it's that dangerous for us, it's just as dangerous (or more) for you.

 

4) I bet a good electrician will scratch his head for about 10 minutes with this problem,

then have it back together, nice & tidy, with good tight splices, and everything working like it should within the hour.

(just saying :D )

 

Good luck Pete.

[Pete M]

lots of good tips guys, thanks. :cheers: we discovered all this at the end of a long day and will be picking up where we left off monday when our heads are clearer. I'll get this line mapped out if I have to check every outlet in the house. :D

 

few additions:

 

the ground we checked against was the new one we had just run.

 

both original hot wires in the bathroom die with the same breaker.

 

wire colors? they're all brown. :yes: well, the originals are at least.

 

a gfi outlet was going in as part of the upgrade.

 

we didn't pop the beaker on purpose. :D

 

a pro wired in the garage when it was built. almost lost the garage this past year due to a gazillion shortcuts he took.

[kastein]

1) Voltmeters are not the best tool to read voltage.

sounds stupid, I know, but with transient voltages,bad grounds, bad neutrals, etc etc, volt meters only complicate things by giving a very precise reading of a surface charge that's not even really there.

 

That's why an electricians set of "Wiggys" is a volt meter with a solenoid inside it to actually draw a load as it tests.

The load is important because it actually dissipates the surface charge (makes it go away).

 

If you connect the '90v wire' (I'm guessing it's the neutral) to ground with the wiggys, and still get 90v, you have a more serious issue than connecting a voltmeter and reading a surface charge of 90v.

 

2) Electrical stuff can get confusing as the issue gets more complicated.

Always go back to the basics:

 

Find out what is your line in.

 

Find out where/what your loads are.

 

Popping a breaker is not the way to diagnose something.

If doing something trips the breaker, STOP doing that.

 

Most of the time a breaker will trip like it should,

but SOMETIMES it will blow right up in your face.

Yep, breakers blow up every day, might even blow up after tripping like it should 10 times in a row.

Especially when it's a dead short tripping it.

 

 

3) Honestly Pete, the guys most likely to be killed by electricity are electricians, who do the work every day.

If it's that dangerous for us, it's just as dangerous (or more) for you.

 

4) I bet a good electrician will scratch his head for about 10 minutes with this problem,

then have it back together, nice & tidy, with good tight splices, and everything working like it should within the hour.

(just saying :D )

 

Good luck Pete.

x2, I was real confused for a bit while wiring a dryer outlet a while ago using an existing run of 10ga romex (had been cut off and left on the ceiling in the basement going from the dryer outlet to 10' from the breaker box.) Measured it and it read 110V on both hot legs, but I knew I had traced it right... traced it again to make sure. No matter what I did it measured 110 but after tracing it a few times I was sure it was disconnected. It even tested out as electrified using one of those field detector gizmos. So I grounded all the wires temporarily as a test and whaddya know, it read as 0 volts and no longer triggered the field detector.

 

I generally am NOT afraid to run a new wire even if I have to punch a couple holes in the drywall to pull cable, drywall doesn't scare me anymore after I did this:

http://alum.wpi.edu/~kastein/wall_fixing/

[Pete M]

I've got plaster walls (with metal mesh here and there) on the first floor. I fear punching holes. :(

 

 

an electrician friend stopped by today to help out (for some reason I felt a bit better when the electrician is stumped :D ) and he told me:

-the issue probably stems from a shared neutral somewhere (that's still a guess though)

-I should start from scratch with that circuit and run new wire :(

 

he gave me a lot of pointers for running wires without tearing apart the plaster walls, but he conceded that some of it won't be easy and that I might need to retain certain sections of the original wiring. But since most of this circuit is lights (only 2 outlets and I hope to pull both of them off of it anyway), it should be ok in the end as long as the old wires don't disintegrate when I touch them. :ack:

[kastein]

I'd punch holes and not worry about it. As long as the plaster isn't falling off the metal mesh it will not be hard to patch, it's far easier than wood lath + plaster because that is almost always falling off the lath and tough to hold still while patching. If you are careful you can probably even cut the metal mesh with a pair of dykes and then bend it back into place afterwards and spackle it, instead of having to patch the mesh.

[Pete M]

the house works again. we ran all new wires (except for a couple of wires in the ceilings) and in the process added 3 new breakers to the box. Now I just have a lot of patching to do. :(

 

oh, and I have a lot of re-wiring to do in the basement later (mostly putting the last 30 years of new wires up through the joists where they're supposed to be) and one more new circuit to power the outlet on the deck (later on I'll post photos of what we discovered).

[Geonovast]

So you can play Portal now, right?

[kastein]

Make sure to use a gfci outlet (or better, breaker) for that outside one, all bathrooms, basements, kitchens, garages, exposed porches etc are to be powered by gfci breakers while all bedrooms are required to be powered by afci (arc fault circuit interrupting) breakers. The afci requirement is fairly new, within the last 10 years.