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Floating neutral or wiring problem?



 
 
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  #1  
Old March 12th 09, 12:06 AM posted to alt.home.repair
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Posts: 31
Default Floating neutral or wiring problem?

Last night several of the lights and outlets went dark in the house. Then
it mysteriously came back by itself for a few hours, and now these circuits
went out again. All fuses tested ok (unless there is a failed circuit
breaker somewhere). One of the dead circuits is an outlet that is right
below the main panel (so it's not a fuse or breaker in a remote subpanel).
Looking into this further, I tested the voltages going into a subpanel that
is right next to the main panel.

The difference between the two hot phases going into this subpanel show
110v. Between one of the hot phases and neutral it is 120v. Between the
other hot phase and neutral it is only 12v!

Last year the electric company came out to fix a broken neutral wire on the
telephone pole, and this reminds me of the floating neutral problem I had
back then, causing mysterious problems with some of the circuits. Because
there is a major difference between the different phases and the neutral, I
wonder if I should call out the electric company again, maybe their original
repair failed?

Or could this be due to a wiring problem inside the house that I should
check first? Or perhaps a failed circuit breaker in this subpanel?

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  #2  
Old March 12th 09, 12:23 AM posted to alt.home.repair
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Posts: 4,938
Default Floating neutral or wiring problem?

On Mar 11, 7:06*pm, "scorpster" wrote:
Last night several of the lights and outlets went dark in the house. *Then
it mysteriously came back by itself for a few hours, and now these circuits
went out again. *All fuses tested ok (unless there is a failed circuit
breaker somewhere). *One of the dead circuits is an outlet that is right
below the main panel (so it's not a fuse or breaker in a remote subpanel)..
Looking into this further, I tested the voltages going into a subpanel that
is right next to the main panel.

The difference between the two hot phases going into this subpanel show
110v. *Between one of the hot phases and neutral it is 120v. *Between the
other hot phase and neutral it is only 12v!

Last year the electric company came out to fix a broken neutral wire on the
telephone pole, and this reminds me of the floating neutral problem I had
back then, causing mysterious problems with some of the circuits. *Because
there is a major difference between the different phases and the neutral, I
wonder if I should call out the electric company again, maybe their original
repair failed?

Or could this be due to a wiring problem inside the house that I should
check first? *Or perhaps a failed circuit breaker in this subpanel?


Call the Electrc Co now , I would caution against using anything
unless a V meter has pointed to show its ok, I had bad repairs on
the electric co
  #3  
Old March 12th 09, 12:40 AM posted to alt.home.repair
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Posts: 1,565
Default Floating neutral or wiring problem?


"scorpster" wrote in message
...
Last night several of the lights and outlets went dark in the house. Then
it mysteriously came back by itself for a few hours, and now these
circuits went out again. All fuses tested ok (unless there is a failed
circuit breaker somewhere). One of the dead circuits is an outlet that is
right below the main panel (so it's not a fuse or breaker in a remote
subpanel). Looking into this further, I tested the voltages going into a
subpanel that is right next to the main panel.

The difference between the two hot phases going into this subpanel show
110v. Between one of the hot phases and neutral it is 120v. Between the
other hot phase and neutral it is only 12v!

Last year the electric company came out to fix a broken neutral wire on
the telephone pole, and this reminds me of the floating neutral problem I
had back then, causing mysterious problems with some of the circuits.
Because there is a major difference between the different phases and the
neutral, I wonder if I should call out the electric company again, maybe
their original repair failed?

Or could this be due to a wiring problem inside the house that I should
check first? Or perhaps a failed circuit breaker in this subpanel?


If you test between the two hot legs, you should get 240 volts. If you test
from each hot leg to neutral, you should get 120 volts. If you got 120 volts
between the two hot legs, you have a dead leg. You need the check the
breaker or fuses feeding that sub panel



  #4  
Old March 12th 09, 01:02 AM posted to alt.home.repair
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Posts: 31
Default Floating neutral or wiring problem?

"RBM" wrote in message
...
If you test between the two hot legs, you should get 240 volts. If you
test from each hot leg to neutral, you should get 120 volts. If you got
120 volts between the two hot legs, you have a dead leg. You need the
check the breaker or fuses feeding that sub panel


All the 15A circuit fuses in the main panel check out ok when I test-replace
them with a new fuse. I get 0.2 Ohms on the large 100A, and 40A fuses so
they're fine too. So now I'm thinking maybe it's not a floating neutral,
but rather it could be a dead leg on the phone pole? Maybe one of the hot
legs could have broken on the phone pole from the swaying tree branches just
like the neutral line connector broke last year.. would that be consistent
with these symptoms?

  #5  
Old March 12th 09, 01:10 AM posted to alt.home.repair
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Posts: 31
Default Floating neutral or wiring problem?

Just now I tested 8v at a 220v receptacle for the dryer.
  #6  
Old March 12th 09, 01:18 AM posted to alt.home.repair
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Posts: 1,565
Default Floating neutral or wiring problem?


"scorpster" wrote in message
...
"RBM" wrote in message
...
If you test between the two hot legs, you should get 240 volts. If you
test from each hot leg to neutral, you should get 120 volts. If you got
120 volts between the two hot legs, you have a dead leg. You need the
check the breaker or fuses feeding that sub panel


All the 15A circuit fuses in the main panel check out ok when I
test-replace them with a new fuse. I get 0.2 Ohms on the large 100A, and
40A fuses so they're fine too. So now I'm thinking maybe it's not a
floating neutral, but rather it could be a dead leg on the phone pole?
Maybe one of the hot legs could have broken on the phone pole from the
swaying tree branches just like the neutral line connector broke last
year.. would that be consistent with these symptoms?


You want to test at the main breaker, preferably with the main turned off.
You have three legs coming in, 2 hot, 1 neutral. With the main breaker in
the off position you should get 240 volts across the 2 hot legs, and 120
volts from each hot leg to neutral. If you don't get 240 across the 2 hot
legs, one of them is dead


  #7  
Old March 12th 09, 01:22 AM posted to alt.home.repair
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Posts: 31
Default Floating neutral or wiring problem?

Now after this next test I'm really puzzled. I checked the voltage at the
terminals where a door opens the circuit by pulling out the blades on two
100A fuses. This is the door that turns off power completely to the entire
house. Between the top blade and ground it is 123V, and between the bottom
blade and ground also 123V. When testing between both blade receptacles I
would expect to see 240V, but instead it shows 0.2v, as if they're both in
the same phase.

  #8  
Old March 12th 09, 05:49 AM posted to alt.home.repair
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Posts: 321
Default Floating neutral or wiring problem?

On Mar 12, 1:47*am, "scorpster" wrote:
"Tony Hwang" wrote in message

...

Hmmm,
Your mistake was using that Fluke with too an input impedance.
One reason I still often use Simpson 260. Some times El Cheapo
analog meter is better in such as our case.


Which readings would have most likely been different if I had used a better
measuring device? *I thought the Fluke multi-meters were pretty good but it
sounds like high voltage electrical is more tender.


Even cheap (non-Fluke) volt meters are sensitive enough to pick up
stray voltages, if you connect one side to ground and then touch your
fingers to the input or + lead one will often pick up enough random
electromagnetic radio and other electrical 'noise' to get small
reading.

And connect it to even dead wiring such a meter will often pick
voltage from other working wiring running next to it within walls etc.
Posters here have reported 'stray/random' but meaningless voltages up
to 43 or more volts.

A good choice for testing such a situation is a plain bulb. Or a
pocket neon lamp/tester (Maybe that's what's called a wiggie?).

A 230 bulb is best but a low wattage 115 volt can be used if just
touched on wires for a moment.

BTW I have a 230 volt low wattage bulb permanently mounted in my
workshop which monitors the 230 volts; if one side were to go open the
115 volts from the oher ;side' would come through whatever 230 volt
appliance happened to be on and that bulb would light more dimly than
at 230 volts dimly.
The single bulb is a better way to monitor the 230 volts than two
bulbs one from each 'side or leg' to neutral.

If one needed to test best way is to turn off main breaker and see
what voltage is on the incoming wires .............

OR: Turn off all the individual circuit house breakers (every single
one of them) and see what voltage there is on the output of the main
breaker by testing the buss bars or inputs to the individual breakers.
  #9  
Old March 12th 09, 06:46 AM posted to alt.home.repair
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Posts: 4,773
Default Floating neutral or wiring problem?

stan wrote:
On Mar 12, 12:53 am, "scorpster" wrote:
Mystery solved! Southern CA Edison sent over a repair expert tonight within
a couple hours. Turns out that one of the hot legs was broken at the
telephone pole. The neighbor's tree branches are completely tangled around
the wires, putting tension on the wires and causing the entire pole to tilt
at an angle. This unraveled one of the hot wires. He repaired the
connection, and he's sending a crew out within a week to trim the neighbor's
trees, and then replace all the wires between the two poles, for a permanent
fix.

The best diagnostic clue that I found before he arrived was to measure
between the two 100A fuses at the main panel, where this showed 0v instead
of 240v. The reason I still got 123v from between each phase and ground, he
explained, was because of back-feeding from the house circuits.

Tip: keep your trees trimmed near the phone poles, and keep an eye on your
neighbors trees!


Exactly. One of the legs (sometimes but incorrectly called 'phases')
was open.

The two legs, with 230 volts between them are actually the two ends of
a single 230 volt transformer winding; on the pole or underground etc.
The middle or centre point of that winding is the zero or neutral
point. A neighbour had the identical problem with the 230/115 volt
service to his garage. Broken connection at the pole transformer. He
couldn't figure why his 115 volt lights worked but nothing 230 volt
would work!

In non North American jurisdictions several actual 'phases' are
sometimes brought into domestic/residences etc.
In the Middle East my son had 230 volt 3 phase main circuit breaker
panel in his 'villa'.

In Malta the three phases and neutral (4 wires) went along the street
on wall brackets and a different phase (and the neutral) were tapped
into each house!

And over in, for example, the UK everything is 230 volt; no 115 volt
(except in certain special and unusual cases).

Here, in Canada three wires come into house one being the neutral. The
other two being the 230/115 volt legs as described by the OP.

Hmmm,
Pole? I don't see any pole in my neighborhood. Power, phone, cable, all
are under ground. Nothing overhead. 4 wires, one is ground.
  #10  
Old March 12th 09, 06:47 AM posted to alt.home.repair
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Posts: 1,854
Default Floating neutral or wiring problem?

scorpster wrote:
"The Daring Dufas" wrote in message
...

Everyone should have a Wiggy. It needs no batteries
and it's hard to break.

http://tinyurl.com/clx8nz


I might buy one from Amazon. So will this Wiggy really read the voltage
differently than my Fluke? Under what conditions would Wiggy report a
different voltage than a digital multimeter? This comes as quite a
surprise to me that the trusty Fluke would be misleading under certain
conditions.

http://www.amazon.com/Klein-69115-So...8?ie=UTF8&s=hi


The Wiggy is a low impedance device that actually puts
a bit of a load on the circuit being tested. It's like
a calibrated electromagnet. The higher the voltage, the
harder the solenoid pulls against the spring and the
farther the indicator moves. The Fluke meter will measure
induced voltages on wiring that has very tiny current
levels. The Wiggy won't react at all unless it's the type
with an indicator light. You could hook some test leads
to an electric hair clipper and get the same reaction.

TDD
 




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