homeGeek CultureWebstoreeCards!Forums!Joy of Tech!AY2K!webcam

The Geek Culture Forums


Post New Topic  New Poll  Post A Reply
my profile | directory login | | search | faq | forum home
  next oldest topic   next newest topic
» The Geek Culture Forums   » Other Geeky Stuff   » Ask a Geek!   » Low voltage woes

 - UBBFriend: Email this page to someone!    
Author Topic: Low voltage woes
nerdwithnofriends
Uber Geek
Member # 3773

Icon 1 posted September 08, 2007 13:19      Profile for nerdwithnofriends     Send New Private Message       Edit/Delete Post   Reply With Quote 
So, I've been renting the house I currently live in for a couple months. There are various things wrong with it, which the landlord has yet to address. In fact, I haven't seen him since I signed the lease on this place- kind of sketchy, but at least he doesn't bother us.

One of the things that bothers/worries me the most is that in our kitchen, there are two sockets (presumably on the same circuit) that aren't "live". The kicker is, there is a potential across the prongs- about 38 v AC (It seems the normal voltage here is 123, give or take). However, I have reason to believe that as soon as the socket is put under load, the voltage drops to zero, because we've connected a lamp and a fan to this socket and they both refuse to run; I can somewhat understand the fan not wanting to run (even thought I'd think it would at least make an effort), but when a simple incandescent lightbulb refuses to light, it worries me. It should at least get warm or something, right?

None of the breakers in the house (there are two panels; originally, this was intended to be used as two separate apartments- one upstairs, one down) are blown, so this circuit is conceivably receiving a potential. What I'm worried about is that maybe there's a break in the wire somewhere, so if a short circuit were to develop at the socket for whatever reason (we don't use it, so it probably never will), that a spark might arc inside the wire and the house will burn down.

I took the faceplate off the sockets and tested the wires at the screw-terminals, just to be sure nothing was wrong with the socket fixtures themselves; sure enough, I still got a reading of 38 volts.


Has anybody had experience with this before? Do breakers for some reason malfunction after a while and start lowering voltage somehow? The only way for this to happen, I'd think, would be for the breaker to act as a resistor- in which case it would radiate heat, and we'd feel/see that, and our electrical bill would be noticeably higher.

Thrice we've tried to contact our landlord, and thrice have we received no response. If this is something trivial, I'll do the work myself and subtract the cost of parts from the rent cheque; however, I'm not willing to rewire the entire house, in which case I'll get /really/ serious about getting the landlord to send an electrician over.

Any help is appreciated greatly!

-NWNF

--------------------
"The Buddha, the Godhead, resides quite as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain or in the petals of a flower." - Robert M. Pirsig

Posts: 948 | Registered: Mar 2005  |  IP: Logged
Chesty
Assimilated
Member # 2460

Member Rated:
2
Icon 1 posted September 08, 2007 14:32      Profile for Chesty         Edit/Delete Post   Reply With Quote 
Yes you got a problem there. If this house is old (or by the ocean, or both) then corrosion might keep the flow low. Go back to the breaker box and put your meter on each breaker to measure what they are showing. If one is off - replace it.

If all the breakers are working then your easiest fix is to run new wires from the box. there could be any number of places that rodents could have eaten your insulation off, nails could have pierced a wire, or the rubber in the insulation simply degraded over time (people who think plastic does not degrade are just wrong). Any of these might cause a partial drain on that circuit.

Best thing if you're renting is to send a letter to the landlord, certified, detailing the problem and follow up by phone.

If you go in by yourself or ignore this and the house burns down you might find yourself being sued.

Posts: 416 | From: The Beach | Registered: Nov 2003  |  IP: Logged
MacManKrisK

Gold Hearted SuperFan!
Member # 955

Member Rated:
5
Icon 1 posted September 08, 2007 16:07      Profile for MacManKrisK     Send New Private Message       Edit/Delete Post   Reply With Quote 
Measure the voltage from each pole to ground. I bet that you're getting 38V(rms)* from the common (white wire) and a big fat nothing from the hot wire (black wire). If that's the case, it's not really anything /particular/ to worry about except that the hot wire is broken somewhere or disconnected. What it /does/ mean is that you have a dirty common, which might not be so great for electronic devices, but will probably be okay.

A common connection in spec can measure up to 5V(rms), anything out of that is out of spec, but as long as the relative difference between the hot and common isn't more than ~125V(rms), you'll be fine, you just might have a little buzz from your radio, TV, or computer speaker.

*V(rms) is "Volts AC Root Mean Squared", it is the number you get from your multimeter when you read AC voltage with it. IIRC, it's also *about* equal to ((peak voltage)*.667)

--------------------
"Buy low, sell high
get rich and you still die"


Posts: 2331 | From: Southwest Michigan, USA | Registered: Oct 2001  |  IP: Logged
TheMoMan
BlabberMouth, a Blabber Odyssey
Member # 1659

Member Rated:
4
Icon 1 posted September 08, 2007 17:01      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
nerdwithnofriends _________________________ You may or maynot have a serious problem, First an anolog voltmeter and the newer digital meters are too sensitive for what you are trying to find out. Those little neon voltage testers are also too sensitve. test the circuit with a nightlight 7 1/2 watt if it goes dead as I suspect it will then open and close each breaker Open(off) close (on).

If you still have no luck; hook up the meter and turn on only one breaker at a time, then back off. The mains must be on for this test.

My gut feeling is that at some time a wire got cut or opened and now you are seeing stray voltage from an adjacent wire in the main panal.

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5836 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
TheMoMan
BlabberMouth, a Blabber Odyssey
Member # 1659

Member Rated:
4
Icon 1 posted September 09, 2007 07:23      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
nerdwithnofriends __________________ If you are still alive. With your meter check from the sink drain to the ground terminal of the outlet, It should be zero or very low.

Check from the sink drain to the larger of the two parallel openings, it should be zero or close.

The smaller of the two parallel openings is the hot. It should read full line.

Any deviation from those stated especially on the ground or neutral (large openings) don't use the outlet untill the wiring is checked, by a journeyman.

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5836 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
MacManKrisK

Gold Hearted SuperFan!
Member # 955

Member Rated:
5
Icon 1 posted September 09, 2007 11:33      Profile for MacManKrisK     Send New Private Message       Edit/Delete Post   Reply With Quote 
Ignore that MacManKrisK guy, I'd go with what he ^^^^^ said....

--------------------
"Buy low, sell high
get rich and you still die"


Posts: 2331 | From: Southwest Michigan, USA | Registered: Oct 2001  |  IP: Logged
Luke Skywalker
Assimilated
Member # 3096

Member Rated:
3
Icon 1 posted September 09, 2007 14:33      Profile for Luke Skywalker     Send New Private Message       Edit/Delete Post   Reply With Quote 
As I cant add to whats been said about checking the electricals...

Check with your local housing commission, and maybe start looking for a lawyer on this. This is a serious condition, and if your landlord doesnt pop up... court is the way to go. But as also stated, start with a certified letter, and make sure you have copies and all the receipts.

--------------------
Use the Force, Luke.

Posts: 406 | From: The Line Between Time and Space | Registered: Nov 2004  |  IP: Logged
nerdwithnofriends
Uber Geek
Member # 3773

Icon 1 posted September 09, 2007 14:48      Profile for nerdwithnofriends     Send New Private Message       Edit/Delete Post   Reply With Quote 
Okay, so here's what I found with MoMan's Metering Method:

Hot to ground jumps around a lot, but seems to hit 13 VAC a lot.

Hot to neutral is what I reported earlier- 38 VAC.

Neutral to ground registers at about 1 VAC, but I believe this to be a phantom reading, because it's my understanding that neutral ties into ground (given two wires carrying an alternating current at 180º opposition, with each one 120 volts ground-relative, it only makes sense that this is how it would work).

I've always thought that sensitive electronic equipment- pretty much anything that has a rectifier and some transistors- is fairly forgiving about voltage, so long as the mains frequency is clean (which it is, here).

I figured that a purely resistive load- like the incandescent lightbulb I tried plugging in earlier- wouldn't have any qualms about under voltage, or even what kind of current it was being fed; in theory, I should be able to hook up a 60W incandescent to a 120 volt batteries and it should light up just as well as if it were connected to a 120 VAC line (and probably last longer, since it's not cooling and reheating 60 times a second...). Since there is no reactance, even a dirty line frequency would power it fairly well.

Unfortunately, I'm back at square one. The landlord is out till the 12th. If I don't hear from him on the 13th, I'm going down to the property management company by which he is employed to talk to him in person and, failing that, complain loudly.

Thanks for your help guys, it's much appreciated. Unfortunately, I don't think there's much I can do here.

--------------------
"The Buddha, the Godhead, resides quite as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain or in the petals of a flower." - Robert M. Pirsig

Posts: 948 | Registered: Mar 2005  |  IP: Logged
TheMoMan
BlabberMouth, a Blabber Odyssey
Member # 1659

Member Rated:
4
Icon 1 posted September 10, 2007 03:27      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
nerdwithnofriends ____________________ So the night light does not light.

Totally dead outlet, I would guess that it is unhooked at the feed end.

The new NEC requires ground to be ground, not tied to neutral at a receptical. Neutral or center tap of the transformer outside ties to ground up at the transformer and at the meter. Hence the check from sink drain to the ground openning.

A little theory, L1 to Neutral = 120 L2 to Neutral = 120 L1 to L2 = 240 think of it as two car batteries in series, and neutral is the tie point. At the meter and the transformer ground and neutral are tied together.

--------------------
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5836 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
Doco

SuperFan!
Member # 371

Member Rated:
5
Icon 1 posted September 10, 2007 06:07      Profile for Doco   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Given your readings - I would guess that the hot line is just not hooked up. It might be disconnected at the breaker box, or at some junction box.

The 1VAC between neutral and ground is possibly "real" - but nothing to worry about. Seeing them that close together tells me that they are tied together at the breaker box which is where they should be. They should not be connected at any sub-panels or outlets.

The 13V or 38V you are seeing should be the same value, but it's not. Instead what you are measuring is a potential (i.e. voltage) but it won't be able to provide any meaningful current. Assuming that the hot line is disconnected at the breaker box you then have say 50 foot worth of wire between there and your outlet. That wire is a big antenna. It will receive RF energy from everything bouncing around. But more importantly it is probably lying parallel to other lines that have power and current flowing through them. This induces a voltage in your disconnected wire.

Using a light - plug it in, but leave a little bit of space so you can probe the prongs of the plug. I will bet that the voltage drops to 1V or less when you turn on the lamp. This shows that as soon as you give the power a path to ground it has no meaningful current driving ability. Kind of like a static charge.

I've run into this type of problem a bunch as I try to trouble shoot strings of Christmas lights. I'll often see 10-30VAC when using my nice digital multi-meter. However, as soon as I go back to the old cheap POS meter (but analog) it goes back to 0. I figure this is because the digital one has such a high internal resistance that it doesn't let any current through, while the cheaper old analog one allows a little current through thereby causing the voltage to quickly drop to near 0.

As for dealing with the landlord - all I can say is good luck! [Smile]

Posts: 419 | From: Minneapolis, MN | Registered: Mar 2000  |  IP: Logged
hal9000
Geek
Member # 9896

Icon 11 posted September 14, 2007 22:10      Profile for hal9000   Author's Homepage     Send New Private Message       Edit/Delete Post   Reply With Quote 
Man I don’t even think I would have turned on my PC in that house without taking my O-Scope out.

Anyways everyone above did what I would have... No one commented on the breakers? I have seen many of them fail. (third place I lived one stuck closed with about 3 ohms resistance…. Sniff Sniff…hmmm do you smell something burning?)
I would call 911 have the fire dept come over for the cook out, replace the suspect breaker.
Just for giggles I would find the main breaker and disconnect it too before you start, I would hate to find out something else happened.
To verify the circuit is dead invite the land lord over and use some jumper cables and apply the red lead to his testicals and the other to a wet sponge on the back of his neck. Then progressively test each one and see if he jumps around.
Oh while you have it disconnected tie the white and ground together and see if you get any resistance then do the same with the black wire.
Mind you that leaves my other worry .....
The second breaker panel. (sub panel)
Did someone do the daisy chain thing and flip the natural to be the second leg for 220 and bank on the hope that the house plumbing and the rare chance that someone may want toast and a shower at the same time, and prayed they never came in contact with one another? (Second house I lived in, I went through the closed door naked in to the living room where my wife and her guests were sitting… cursing up a storm about being fried in the shower…. That hurt a lot.)

60 cycle shuffle anyone?

Ok I can’t stop laughing and I have no idea why this is funny to me.... I myself have lost more brain cells to electrocution than by natural causes.

--------------------
P.E.B.K.A.C. if you can fix this, you can fix anything.

Posts: 183 | From: VA under a bridge living in a van. | Registered: Jul 2007  |  IP: Logged


All times are Eastern Time  
Post New Topic  New Poll  Post A Reply Close Topic    Move Topic    Delete Topic next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:

Contact Us | Geek Culture Home Page

© 2015 Geek Culture

Powered by Infopop Corporation
UBB.classicTM 6.4.0



homeGeek CultureWebstoreeCards!Forums!Joy of Tech!AY2K!webcam