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mnalep
11-22-2008, 09:29 AM
Can voltage in a run of outlets/lights be reduced to the point it lights a test lamp, but not enough to light a 4 watt bulb? Below is a description of my problem:

I have a run of three outlets (maybe other receptacles too) that ends with a ceiling light receptacle in the basement. The light stopped working, and my mom asked me to put a new light receptacle in. I did, but the light still did not work (bulb is good, fuse is good).

I saw an outlet that feeds the light receptacle, and tested for current at that outlet. My test lamp lit up when I inserted the prongs in to the hot and neutral slots. What was odd was my mom got a small candle light (with about a 4w type nightlite bulb in it) - and it would not glow! So it looks to me like there is just a trickle of voltage - enough to light the test lamp (which I guess has to be like a 1/10th of a watt), but not enough to light the higher 4 watt bulb (or the 100 W bulb in the light receptacle).

At least 3 outlets in front of that light receptacle also show this reduced voltage. What would cause this? How would I test?

The other thing I tested was the ground at the outlet that feeds the light receptacle (at the end of the line). I don't know if the receptacle is grounded properly, or has anything to do with the low voltage, but this is what I found.

When the low voltage was present at the outlet, my test light lit up when I put on probe in the hot slot and the other in the round ground slot(but not the other neutral slot, so I thought it was properly grounded). Then I pulled the off/on chain at the new light receptacle, and saw the outlets in front of it would not light my test lamp. Also, at the same time that these outlets did not show power on the test lamp - both the hot slot and the neutral slot tested like they were both grounded! Is that correct?

Is it possible that trying to turn on the light bulb at the light receptacle could "suck" the little voltage past the outlets in front of it to the point that they would not then be able to even light my test lamp?

I'm no genious with this stuff, so be gentle please. But I would appreciate any insight as to what may be wrond, and how I can test and correct this for my mom.

Thanks, Matt

Thatguy
11-22-2008, 11:48 AM
Can voltage in a run of outlets/lights be reduced to the point it lights a test lamp, but not enough to light a 4 watt bulb?
A neon test lamp can draw less than 1mA and fire at ~60v. Were both rods inside the bulb lit, or only one? Visible flickering or not?

A 4w lamp takes ~30mA. About 200' of ungrounded Romex can have enough parasitic capacitance to supply this current at 120v.

If your test lamp isn't neon then I don't understand what is happening at your house!:eek:
In that case you might want to put these two guys
http://www.youtube.com/watch?v=Ewu1laA2nmI
on Speed dial.

Rowdy
11-22-2008, 12:41 PM
Your situation sounds interesting, A real learning experience.

If all other circuits in the house are working properly, then you can assume that only the troubled circuit has a problem, or two.

What I would do is to identify all fixtures in this circuit, shut off the breaker and go one by one and make sure that all connections are correct and tight.

Use your tester or buy one that will get you good voltage readings, so that you can be assured that your power is off and does not have power coming in from a feeder from another circuit.

Up to date receptacles have three slots.

A large slot which is for a connection to the grounded conductor some say neutral which should be white.

A small slot for connecting to the ungrounded conductor, this is your hot should be black.

A circular shaped slot which is for connecting to the grounding conductor, should be bare or green.

Older receptacles that have two slots have a large and small slot also, unless they are really old. Many years ago they did not care because AC moves and they did not think it necessary to distinguish between hot and grounded at the fixture.

Pull the receptacles out.

If these receptacles are the type that you push or stab the wires into a hole, move the wires to a screw type terminal.

Identify the large slot and make sure all connections on that side of the receptacle are white and tight.

Identify the small slot and make sure that all connections on that side of the receptacle are black and make sure they are tight.

While you have them apart look for connections inside the box that are wired together with wire nuts etc. and make sure they will not pull out of the wire nut or other device that was used to make the connection.

Make sure all connections are tight for the bare while your at it, if someone didn't get one connection tight, there are most likely others that are not tight.

If that doesn't take care of it, I would call a qualified electrician.

Rowdy
11-22-2008, 02:01 PM
You say the fuse is good, how good? You might try to replace that first just to be sure.

mnalep
11-22-2008, 02:18 PM
Rowdy, I'll try a other fuse (but the one in there now is the 2nd one I tried already).

mnalep
11-22-2008, 02:23 PM
Thatguy, I guess this is a neon tester. It has 2 small tubes in it that glow orange when inserted in an outlet. The tester did seem to be less bright in the outlets I suspect have a problem in them.

I put a multitester on the lines, and if I am reading the multitester correclty, it was telling me the outlet had about 45 volts. I'm not sure I read the meter correctly, as an outlet I considered good, was only slightly higher, at what I though would be about 50 volts (makes no sense - i know).

My meter was set on the 250V dial setting, and the meter needle went to about 5v on the bad outlet, and 10v on the good outlet. The instructions on my meter say to add 40v to the reading from the needle reading on the meter. (Which does not make sense to me either).

So I may very well be reading the meter incorrectly.

mnalep
11-22-2008, 02:42 PM
Rowdy, thanks for the reply. I hope we do learn something here.

I have some additional info from more observation and testing.

First, I put a 3 prong ground tester into all 4 of the outlets, and the outlet on the new light bulb receptacle I just put up.

On the 4 regular outlets, the 3 prong ground tester indicated HOT - GROUND REVERSED.

On the outlet on the light bulb receptace it gave me 2 different indicators, based on me pulling the chain for the light bulb. In one chain pull position it says HOT - GROUND REVERSED, in the other pulled position it says OPEN NEUTRAL.

I also found that there are 2 other light boxes on this run. Neither of them were ever outfitted with a light appliance, they were just left with the wires twisted together in the steel box. I tested and found they were on the same circuit, in between the 4 regular outlets, and before the last light outlet I just replaced. What was strange was the test lamp did not glow when I touched the black/white wires in these 2 boxes. But thet test lamp did glow when I touched the black wire to the steel box, AND when I touched the white wire to the steel box. This can't be correct, can it?

I also noticed that 3 of the 4 regular outlets are upside down in the boxes, that is, the round ground slot is at the top, instead of below the HOT/NEUTRAL slots. These have been like that forever, so I assume that is not the reason for my new problem.

I did pull the 1st outlet out, and the wires are pushed in, not wrapped around the screws, so I am thinking that if I am going to take those apart, I might just as well get 4 new outlets also?

One thing I did notice on the outlet I pulled out, was that there were two cables, one coming in, the other going out. The black wires were pushed into the outlet, as were the white wires. But, the white wire locations did not seem to be in the same orientation as the black - by which I mean the input cable's black wire was in the upper push in, the output cable's black wire in the lower push in, but the input cable's white was in the lower push in (I expected it to be in the upper) and the output cable's white wire was in the upper push in. I don't know if that is ok or not, but it seemed odd to me.

Also the bare ground wire was twisted with a wire in the box, and then attached to a green ground screw in the outlet. It had a bit of a green tinge on it. Is that copper oxidizing? Is that ok?

Whew...lot's of info to post.

Thatguy
11-22-2008, 03:28 PM
So I may very well be reading the meter incorrectly.
No, you're correct for hard-to-explain reasons.
Read the 45v when you load it down with a 4w lamp.
In fact, to avoid confusion, any household voltage readings should be loaded down with an incandescent lamp.
What make and model meter are you using?

hj
11-22-2008, 05:28 PM
Hot/ground reversed on an outlet often means it is controlled by a GFCI and the neutral has failed.

Rowdy
11-22-2008, 05:41 PM
Hi again, sounds like there are multiple problems, but I stick by my earlier post, until you verify that all connections are correct and tight you will be guessing and so will I.

Most voltage problems are because of a loose or missing connection, most common the white or grounded connections.

By reading your post, my first thought was that you had receptacles that had stab connections, they last for a while then develop loose connections, in other words I do not like to use the stabs.

The second thought is an open neutral or very loose connection, again a symptom of stab connections that were used and worked fine for a number of years then all of a sudden with a change in weather voltage or some other factor the weak link starts giving you trouble.

Even though you show an open neutral on one fixture which at first would seem to be the culprit, I would still check them all for correct connections and tight connections or you will end up with the same problem in a week a month or a year.

Hopefully by the time you read this post you will already have all the connections correct and tight, and hopefully the problem will go away.

Rowdy
11-22-2008, 11:09 PM
mnalep, Sorry for the interruption, neighbors stopped over and I didn't finish, they are gone now and it is late. I will make this as brief as possible.

If your receptacles are wired correctly and tight and are still showing hot neutral reversed, somewhere prior to that part of the circuit is wired backwards, could be the new fixture you installed, if not what else has been changed? It is possible that they have been backwards since installed.

The condition in your empty fixture boxes also indicates an open neutral, if you pull the chain on the light fixture does the neutral in the empty box light your test light? If so, you may have your neutral feeding through the light fixture in series with your neutral branch. I wish I could come over and see this for myself.

How many wires enter the box where your lighting fixture is installed?

Could one run of romex be a switch-leg? If so you may have a white wire that is hot and not identified.

I don't know how old the wiring is in your mothers house, but some older wiring is difficult to determine as over the years one fades the other discolors. It sounds like you have newer wire runs, hope so.

There are so many things that could be your problem that you may have to get an electrician to come over and look things over, I have most likely already ticked off a lot of them.:p

It doesn't matter how the receptacle sets in the box, with the grounding slot up or down, many have a preference but it just doesn't matter. As long as the proper connection are made and all are tight you are good, I prefer them on the bottom, but just a personal preference, my logic is that if something were to fall on the cord the grounding wire would still be available to trip the breaker or blow the fuse and I have never seen anything fall up. There are arguments for the reverse, but I still prefer them down.

As far as where your wires are connected to the receptacle, as long as they are on the correct side everything should work, I just wouldn't do it that way, I would keep them uniform so that I feel good about the work that I have done.

Hope this helps, if not send me an airline ticket, :)

jimbo
11-23-2008, 05:59 AM
Let's stay fairly basic on this....

Your original post said you had a test of "hot/ground reversed".

Someone has already pointed out that those plug in testers will indicate that signal when the actual problem is an openneutral.

Since it would be VERY unusual to actually have reversed hot and ground, just start looking for that loose or broken connection in the neutrals.

Thatguy
11-23-2008, 09:24 AM
BTW, you should probably make your measurements with respect to a known-good ground. You may need an extension cord to bring this ground to your problem outlet.
Without knowing anything else, the chance of randomly correctly connecting 1, 2, or all 3 wires to a three terminal outlet is about 3 out of 100. It's harder than it looks.

mnalep
11-23-2008, 04:56 PM
No, you're correct for hard-to-explain reasons.
Read the 45v when you load it down with a 4w lamp.
In fact, to avoid confusion, any household voltage readings should be loaded down with an incandescent lamp.
What make and model meter are you using?

Thatguy,

The multimeter is MICRONTA (made by Radio Shack) CAT NO. 22-201U.

The probes can be put in 1 of 4 input jacks. I used the -COM and +V jacks(the other 2 jacks are labeled OUTPUT and DC1000v).

Where I am confused is the dial has 4 ACV ranges (10, 50, 250, and 1000)., but the needle and scale on the meter only has 1 scale. (As opposed to say the DCV dial setting, which has 4 corresponding scales that the needle can point to.)

In the corner of the meter it says for the following Volt ranges (10,50,250 and 1000) to add (0db, 14db, 28db, 40db) respectivley.

So, with the needle pointed to the 10th mark on the AC scale (just above the 1 on the DCV scale) and when I had the meter dial on 250 ACV- what would the AC voltage reading be?

I've taken some pictures of the meter and attached them below, but it was hard to get a clear focus with my digital camera.

Thatguy
11-23-2008, 05:18 PM
I couldn't find a pic of the face for this meter on the Web. With these meters I just try to remember that 250v is full scale, so if the needle is sitting at 4/5 of full scale you must be reading 4/5 of 250 = 200v. It's written on the meter face somewhere, in red or in black.

It's sensitivity is 10,000 ohms/volt on AC, so on the 250v range it presents a resistance of 2.5 MΩ to what you're measuring. Your phantom voltage for 50' of grounded Romex could be ~60v; less Romex, less voltage. In this application and on this scale it reads almost the same as if the meter had 10MΩ or 20MΩ input impedance.

On the 50v range the meter presents a resistance of 500kΩ, so it might read 43v or less; less Romex, less voltage. The capacitive reactance of the cable is "at right angles" to the meter resistance, so figuring this 43v is a bit involved.

Digital meters usually present a constant high impedance to the line, 10MΩ or 20MΩ, so the readings still look strange but at least they don't change depending on the range you are on.

jadnashua
11-23-2008, 05:20 PM
If it was in focus or didn't have the glare, it would be easier...

If the range/mode scale is on 250 or say 25, look for a scale that ends up at 250 and read those values. So it it went from 0-25, 10 would be 100 if the knob was on 0-25.

Redwood
11-23-2008, 06:35 PM
The red scale just below the mirror would correspond to AC and the black scale just below the mirror would correspond to DC.
The numbers below would be used for both by using whichever range was selected.

The scale at the top is ohms and the one at the bottom is db.

mnalep
11-23-2008, 07:23 PM
I tried to take a better picture, but could not improve on the one above - so I read that picture into PAINTBRUSH, and tried to DRAW the numbers that are on the dial face of the multimeter. (I also drew in about where the needle was as the black line)

The red AC scale has no numbers below it, and only says AC at the beginning and end of the range scale.

The 4 DC scales are below the red AC scale.

(OHMS in green, and dB in black at the bottom)

So you are saying that if the needle lined up under the RED mark that is just above the '1' mark on the DC scale, and if the AC dial was on 250, then I would interpret that as 1/5th of 250 - 50 AC volts? (Likewise if the dial was set on 50 AC, the needle in the same place, then I'd interpret that as 1/5th of 50 - 10 AC volts?)

PS: I totally don't understand the sensitivity, OHMS/Volt, and resisitance you wrote about?

Redwood
11-23-2008, 07:45 PM
What I'm saying is that the lines in red are for AC and the lines in black are for DC.

The numbers below are for either the red or black scale. It is the use of the red or black graduations that are important.

If you are set on the 0 - 250 volts the number scale below used would be the 0 -25 scale with a "0" added to the reading.

If you are set on the 0 - 50 volts the number scale below used would be the 0 - 5 scale with a "0" added to the reading.

mnalep
11-23-2008, 08:14 PM
Hey Redwood,

I think I got it now. Thank you.

If I understand correctly, then where I drew the needle would be read as:
10 volts if I my dial is set on the 50.
50 volts if the dial is set on the 250.

? 2 volts if the dial is set on 10 ?
? 200 volts if the dial is set on 1000 ?

PS: So how would I interpret if I was reading DC voltage? (My settings on the DC voltage dial are 5, 25, 125, 500/1000).

Redwood
11-23-2008, 08:27 PM
You would then use the black graduations and apply the numbers pretty much the same way. Pick the number scale thats close and add "0's" as needed.

Cass
11-24-2008, 05:32 AM
WoW...you can make life much easier if you go to a big box store and buy a voltage tester that looks something like this

http://www.theworkshop.net/news/img/voltage%20tester.jpg

Then start at the main pannel...find the problem circuit...and trace it back until you find the problem...You may find a tester like the one above is easier to use and safer...

Better still call an electrician to trouble shoot it for you...like jwelectric below is inferring...he may be right about the outcome...

jwelectric
11-24-2008, 05:54 AM
If this dude doesn't know how to read the meter he is using pray tell me why are we trying to tell him how to put his hands into something that could kill him?

Just which of us is more stupid? The guy not knowing or us trying to help him kill himself?

Redwood
11-24-2008, 06:45 AM
If this dude doesn't know how to read the meter he is using pray tell me why are we trying to tell him how to put his hands into something that could kill him?

Just which of us is more stupid? The guy not knowing or us trying to help him kill himself?

I would tend to agree...:eek:

mnalep
11-24-2008, 07:11 AM
If this dude doesn't know how to read the meter he is using pray tell me why are we trying to tell him how to put his hands into something that could kill him?

Just which of us is more stupid? The guy not knowing or us trying to help him kill himself?

jwelectric,

"DUDE", I appreciate you looking out for my well being. But please do not discourage the people here from answering my questions.

The fact is that I may not know exactly if my multimeter is telling me there is 25 volts, or 50 volts on a line - but I DO understand there is voltage in the lines - and I am not going to put my hands on any line, with any voltage, in it!

Also, if the instruction booklet that came with this meter, was written with any clarity at all, or even just an example, I would already know how to read the meter.

If those with experience stopped training those without experience, how would we ever get new electricians, policemen, or any other profession where a 'learner' could get injured. No one would ever learn how to do things for themselves, or around their home or automobile.

We all have to learn somewhere.

Please don't discourage people from helping others, or answering questions on this forum.

Cass
11-24-2008, 08:20 AM
jwelectric,

"DUDE", I appreciate you looking out for my well being. But please do not discourage the people here from answering my questions.

The fact is that I may not know exactly if my multimeter is telling me there is 25 volts, or 50 volts on a line - but I DO understand there is voltage in the lines - and I am not going to put my hands on any line, with any voltage, in it!

Also, if the instruction booklet that came with this meter, was written with any clarity at all, or even just an example, I would already know how to read the meter.

If those with experience stopped training those without experience, how would we ever get new electricians, policemen, or any other profession where a 'learner' could get injured. No one would ever learn how to do things for themselves, or around their home or automobile.

We all have to learn somewhere.

Please don't discourage people from helping others, or answering questions on this forum.


We as professionals giving help through suggestions on this forum also have to judge by what questions are asked, the level of ability the questioner has, because we have no idea...most DIYrs that have to ask about something we regard as basic sets off a alarm that leads us to believe, right or wrong, that the DIYer is heading into an area that he/she knows little or nothing about...An open electrical panel is not where a novice with no knowledge needs to be...enough experienced electricians that become complacent are injured and some die even though they are well trained. Something as simple as wearing a wedding band while working in a panel can be deadly.

So if you find sometimes that it seems someone does not want to help it is due to caution and us knowing what can happen to someone who, in our opinion, is somewhere he has no business being and doing something he has no or limited knowledge about.

It is a moral call each individual has to make. So don't take it personally, we have no way of knowing what your level of ability is.

It boils down to many people knowing just enough about something to be dangerous or deadly and us trying to figure out if your one of them.

Rowdy
11-24-2008, 08:35 AM
mnalep, It is my understanding that you have tested for voltage, checked your fixtures for good connections, checked continuity between neutral and ground, and then checked them all again and again.

Your tests aren't producing results so it is time to try basic troubleshooting. Talk to your Mother and try to get as much information as possible on the problem, when the light fixture stopped working? What was going on at that time, like remodeling, putting screws or nails into the walls, installing new fixtures and as many other changes that she can think of.

Someone said a GFI may be tripped in the circuit, with voltage present I have my doubts, but look for a tripped GFI, inside, outside, in the garage or any other place that there could be one.

Try isolation:

By now you know the circuit pretty well, shut the power off and go to wherever you feel is the center of that circuit and remove the fixture, tape all exposed wiring individually so that there is no chance of anyone getting hurt then turn the power back on and see if the problem exists in that half of the circuit. If there is a problem there, shut the power off and remove the fixtures one by one taping all of the bare conductors and turning the power back on.

Sometimes testing only leads to frustration, try isolating and see if that will get you results. Good Luck.

mnalep
11-24-2008, 09:59 AM
Cass, I hear what you are saying. I will take his comment in stride. Thank you.

mnalep
11-24-2008, 10:04 AM
Rowdy, Thanks for your help.

I have not yet moved the wiring from the push in's to the screw terminals. I plan to try that tonight or tomorrow.

I like the idea of disconnecting the circuit in the middle and observing if the problem still exists on the first half of the circuit. Divide and conquer.

BTW, There is no GFCI's anywhere in my mom's house. I examined at all the outlets when I was observing to determine all the outlets and lights on this one bad circuit.

Thatguy
11-24-2008, 10:59 AM
PS: I totally don't understand the sensitivity, OHMS/Volt, and resisitance you wrote about?

It's a bit hard to understand.

A measuring device should not change the circuit voltage when you hook it up to read voltage. The higher the sensitivity of the meter, the less the voltage you're measuring is dropped when you hook up your meter.

I have a DVM that has 20 MΩ input impedance, so if it's measuring 20v it only pulls 20/20MΩ = 1ľA from the circuit it's measuring. This is OK for almost all applications except vacuum tube circuits, and there aren't very many of them around anymore.

My 1000Ω/volt meter on the 20v scale would pull 20/20kΩ = 1 mA from the circuit being measured.

You can pull about 5A out of household circuits and only drop the voltage ~1%, except when measuring these phantom voltages.

mnalep
11-25-2008, 07:03 AM
I have put in 4 new outlets, made sure they are all black wires to brass screws and white wires to silver screws, and that the bare ground wire on the green grounding screw.

I thought I was doing good, but no success. I tried disconnecting at the middle of the circuit, and ended up at the first outlet.

At that first outlet, with the rest of the circuit disconnected I put the 3 plug circuit tester in, the tester gave me 2 green lights, but the middle green light on the tester was very weak (2 green lights is supposed to be OK).

With that tester still in the bottom slots of the outlet I plugged in a 4 watt light (a little candle light) into the upper slots - and the 4w bulb did not glow, and the tester changed to HOT/GROUND reversed (1 green and 1 orange light).

SO, I'm thinking the problem has to either be in the wire from the fuse box to the first rececptacle, or at the fuse box?

Is the tester actually telling me that the ground wire is now HOT? (I guess that would explain why the 4w bulb is not lighting, as it is on a 2 prong wire that is plugged into the hot and neutral slots of the outlet, and if the hot slot is not hot - because the ground wire is hot - then the bulb would not light?)

I did notice yesterday that in the fuse box, the screw in receptacle for the base of the fuse was a little wobbly, although it got good and firm (no wobble at all) once the fuse was screwed in. This would not be causing the problem, would it?

What would you test or look at next, to find the problem?

I am thinking that next I should pull out the ceiling tiles and trace the wire back to the fuse box, and make sure that the wire from the fuse box to the first receptacle is intact. And if that wire is intact, then the next thing would be to open the fuse box and see if there is any problem in there?

A few people said this could be an OPEN NEUTRAL also., but I'm not sure how to test to confirm OPEN NEUTRAL vs HOT/GROUND reveresed? If the ground wire is HOT, shouldn't I be able to put a test lamp on the ground wire and the steel receptacle box and see it light up?

Rowdy
11-25-2008, 07:35 AM
mnalep, You have done a lot of work on this circuit, you have isolated the problem to the point that an electrician come come in and fix it with minimal expense.

They will have access to any parts that are needed, the knowledge to work in the panel etc.

I feel it is time to make that call!

Your mother may have a leak in her roof next year, would be nice if you were around to fix that for her:)

Thatguy
11-25-2008, 10:09 AM
Post a schematic of what you think you have.

Measure voltages & resistances with respect to a known good ground. It used to be you could use a cold water pipe for a ground, but now it's kind of iffy. If a lamp between the short slot and ground lights, it is a good ground and a good short slot.

Any voltages measured should be done while the voltage is loaded down with an incandescent lamp.

What makes this difficult is all the permutations and combinations involved with 3 wires and 3 terminals. And, that neutral and ground will read the same ohms to ground because they are connected at the panel.

Wear face protection; shorts can spectacularly vaporize copper, or screwdriver tips, before the breaker has a chance to trip.

The worst outcome is to be on the evening news.:D