Outlet Stopped Working - Electrical - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 07-19-2008, 10:47 AM   #1
Newbie
 
Join Date: Jul 2008
Posts: 4
Rewards Points: 10
Default

Outlet stopped working


My house was built before 1920. I have one three prong outlet that is on its own circuit breaker with old wiring. It stopped working after working fine for over 20 years. The circuit breaker was still on. Upon opening the outlet box I found that the case ground was connected to the outlet neutral and ground. The "white wire was not connected to anything and was wrapped with electrical tape. Using a multimeter I found that there was 56 volts across the outlet, 96 volts from hot to white wire, and 25 volts between the white wire and ground. There are no loads on this line as far as
I know. What could be going on? how can I fix it?

Advertisement

nealt is offline   Reply With Quote
Old 07-19-2008, 10:56 AM   #2
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Outlet stopped working


Quote:
Originally Posted by nealt View Post
Using a multimeter I found that there was 56 volts across the outlet, 96 volts from hot to white wire, and 25 volts between the white wire and ground. There are no loads on this line as far as
I know. What could be going on? how can I fix it?
Load down your high input impedance voltmeter with a 4w to 100w bulb using one of these
http://images.orgill.com/200x200/4186144.jpg

If the voltages don't drop to ~0v search for a bad neutral connection [one that shows >> a 3 millivolt drop across it].

If they do drop to zero, those wires are not connected to anything and the voltages are due to ~100 picofarads per foot of parasitic capacitance in the cables.

Advertisement


Last edited by Yoyizit; 07-19-2008 at 11:00 AM.
Yoyizit is offline   Reply With Quote
Old 07-19-2008, 11:06 AM   #3
Newbie
 
Join Date: Jul 2008
Posts: 4
Rewards Points: 10
Default

Outlet stopped working


Thanks for the reply. Should I put the load across the hot and "white" wire which would seem correct or between the hot and the green wire, the way the outlet was originally wired many years ago?
nealt is offline   Reply With Quote
Old 07-19-2008, 11:20 AM   #4
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Outlet stopped working


The bulb goes across your voltmeter leads, converting your meter into a low input impedance voltmeter.

Then any measured voltages that stay above ~0v have a low source impedance.
The source impedance of a good, correcly wired outlet measured across the short slot and the long slot should be about 1/4 ohm, per page 7 of this
http://www.idealindustries.com/media/pdfs/products/instructions/61-164-165_instructions_v4.pdf

So if an outlet measures 120v and you load it down with a hair dryer pulling 10A, the voltage should drop no more than 1/4 x 10 = ~2.5v.
You are measuring the Thevenin Equivalent Impedance.

I recommend reading the voltages between a known good ground, like a cold water pipe, and the wire to be tested.
120v that lights the bulb is almost certainly the hot wire and is supposed to be the black wire.
Then, 120v that lights the bulb between this hot wire and the others almost certainly means the others are neutral or ground.

Don't qualify for a Darwin Award!

Last edited by Yoyizit; 07-19-2008 at 11:42 AM.
Yoyizit is offline   Reply With Quote
Old 07-19-2008, 01:51 PM   #5
Newbie
 
Join Date: Jul 2008
Posts: 4
Rewards Points: 10
Default

Outlet stopped working


With a load on the hot and "white" wire the voltage across the load dropped to zero. However the voltage between these wires and ground is 28 volts. Any more ideas?
nealt is offline   Reply With Quote
Old 07-19-2008, 02:20 PM   #6
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Outlet stopped working


Quote:
Originally Posted by nealt View Post
With a load on the hot and "white" wire the voltage across the load dropped to zero. However the voltage between these wires and ground is 28 volts. Any more ideas?
So far, so good. . .

So the voltage across hot and white drops to zero with a lamp load? This means these two wires are not connected to a "stiff" (~1/4 ohm) source, but one of them may still be.

Voltage, hot to Known-Good-Ground with lamp load =?
Voltage, white to KGG with lamp load = ?

One conductor of a 50' extension cord makes a good, long voltmeter test lead to connect to your good ground.

I find that it is sometimes difficult to get a good connection by poking a voltmeter probe into a socket so I recommend you plug in a turned-off appliance and then retract the plug just enough to contact the plug blades, 1/4" or so.

If your plugs pull out easily, you have another problem in that the spring contacts are weak, which cause high temps in the outlet and shorten motor lifetimes.

Last edited by Yoyizit; 07-19-2008 at 02:35 PM.
Yoyizit is offline   Reply With Quote
Old 07-19-2008, 03:00 PM   #7
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,247
Rewards Points: 2,464
Default

Outlet stopped working


Jeez why don't we make this as complicated we can.....

Nealt

Take the bulb tester and forget the digital multimeter. Touch (carefully) the black wire the other black ...touch white to ground does it light the bulb?... N0....open ground or no power on the black.


Test black wire to black and white wire to white...does not light the bulb... ...open neutral or No power on the black.

Do you have voltage at the breaker terminal....?
Stubbie is offline   Reply With Quote
Old 07-19-2008, 03:45 PM   #8
Newbie
 
Join Date: Jul 2008
Posts: 4
Rewards Points: 10
Default

Outlet stopped working


Well I discovered that there is a hallway light on the same circuit breaker. It is working fine. Also the wiring to the circuit breaker is relatively new. So somewhere there must be a junction box. I have not been able to find it.
nealt is offline   Reply With Quote
Old 07-19-2008, 04:27 PM   #9
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 5,247
Rewards Points: 2,464
Default

Outlet stopped working


Hi Nealt

You are on the right track while you have the hallway light switch box open and the ceiling fixture you need to check the connections and find everything powered by that breaker.

When you say the wiring to the breaker box is new are you talking very recently and the outlet stopped coincidently with that work?

Also using the ground as neutral is a no-no so when you find the problem you need to get that unused white wire at the outlet connected as the neutral and the ground to the equipment ground.
Stubbie is offline   Reply With Quote
Old 07-19-2008, 04:46 PM   #10
Power Gen/RS Engineer
 
Join Date: Jun 2006
Location: Oak Park, Illinois
Posts: 751
Rewards Points: 500
Default

Outlet stopped working


Quote:
Originally Posted by Stubbie View Post
Jeez why don't we make this as complicated we can.....
A-f'ing-men!

Whenever HO's ask me about test equipment, I always tell them to get a wiggy (or just borrow mine). 99% of the time, we just need to know if we have zero, 120 or 240V or measure for continuity.

In my line of work which deals with low voltage DC signaling circuits (12 or 24/28V DC), the good guys all carry a test light which is nothing more than a 12V incandescent bulb connected to a couple of aligators. Especially when you're dealing with line circuits that can be on the order of miles in length, DVM's will lie like a rug. But a test light never does.

Advertisement

__________________
Well, now, there's what's right and what's right and never the twain shall meet.
BigJimmy is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Water Dispenser Stopped Working dgoldb1 Appliances 20 05-16-2011 06:48 PM
Rheem furnace stopped working kgsolomon1 HVAC 1 02-09-2008 07:51 PM
Outlet not working? Madnpc Electrical 3 12-07-2007 06:51 PM
Outlet in garage quit working Thirdeye Electrical 10 07-01-2007 11:32 PM
Light Stopped Working gershon Electrical 5 01-10-2007 09:03 PM




Top of Page | View New Posts