wrote:
On Sat, 08 Nov 2008 11:43:10 -0500, wrote:

On Fri, 07 Nov 2008 18:16:17 -0800, Smitty Two
wrote:

So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

Bad CFCI, and an attached downstream load. Try tripping the GFCI and
resetting it a few times. They disconnect the neutral and it is not
closing properly. Sometimes just cycling it will clean the contacts.
If not, replace it.


If the house is to code, none of these explanations really hits it,
because there CAN NOT BE another load on the line, as refigerator plug
needs to be a separate circuit.

I know, in my hose it is not either (has an external receptacle on the
same line) but the wiring has all been there for 35 years.


My house was built in 2001 and the fridge outlet is on one of the 2
kitchen 20A circuits. I don't know if that was code or not.
They did have a dedicated circuit for the built-in microwave but they
had a 20 amp breaker on 14 ga wire. I changed the breaker to 15A but the
MW is rated at 14A so that is still a violation I believe.

Kevin

Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?


IMHO all 3 lights lit indicates voltage between each pair of wires.
Assuming the outlet is not connected to 220 that requires one wire,
probably ground, to be not be connected or be open back to the panel.

Post what you find Smitty.

--
bud--

On Sat, 08 Nov 2008 13:43:11 -0500, wrote:

On Sat, 08 Nov 2008 12:30:54 -0500, wrote:

Bad CFCI, and an attached downstream load. Try tripping the GFCI and
resetting it a few times. They disconnect the neutral and it is not
closing properly. Sometimes just cycling it will clean the contacts.
If not, replace it.


If the house is to code, none of these explanations really hits it,
because there CAN NOT BE another load on the line, as refigerator plug
needs to be a separate circuit.

It is perfectly legal to have the fridge on a 20a small appliance
circuit. It is only when you serve it from a 15a circuit that it must
be dedicated.

This is also a fairly recent rule(1996) . If you have an old house the
fridge might be on with just about anything. Prior to 96 you could
even have outdoor receptacles on the SA circuit.


But the "total remodel" would have required bringing the house totally
up to code. House was likely built with knob and tube. The fact there
are open grounds in several bedrooms would make me severely question
if the house was totally and properly rewired.

My guess? There is a LOT that is not up to code, and a lot of corners
were cut. Get a trustworthy electrician in there and have it checked
out. Two hours should tell the majority of the story and save you a
lot of expensive grief over what you don't know now.

In article ,
Kevin Ricks wrote:

Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

This happens when there is an open neutral elsewhere in the circuit AND
something else is connected to the same circuit and turned on. A
disconnected neutral at the panel would do this but the disconnect could
be anywhere along the line. The neutral between the outlet and other
load(s) would have to be intact.

Voltage is fed back though the other load, say the filament of a light
bulb, into the floating neutral and fooling the tester. The light would
be switched on but not glowing.

Did the inspector say something else was not working?

To get more accurate reading you would have to disconnect all other
loads from the circuit. Don't forget any direct wired appliances or
hidden things like a door bell transformer.

Note that using a volt meter in this case will give you the same crazy
readings. You will see 120V from hot to ground AND 120V from neutral to
ground. The 120V on neutral will go away when the other load(s) is
removed.

Kevin

I'm having a hard time visualizing what you're postulating. I made a
sketch of what I believe a circuit with a fridge and downstream load
would look like, but can't quite picture which wire(s) would be open to
cause the indication.

http://members.cox.net/prestwich/wiring.jpg

I suppose I'd have to start by asking whether my sketch is accurate.

In article ,
wrote:

On Sat, 08 Nov 2008 13:43:11 -0500, wrote:

On Sat, 08 Nov 2008 12:30:54 -0500, wrote:

Bad CFCI, and an attached downstream load. Try tripping the GFCI and
resetting it a few times. They disconnect the neutral and it is not
closing properly. Sometimes just cycling it will clean the contacts.
If not, replace it.


If the house is to code, none of these explanations really hits it,
because there CAN NOT BE another load on the line, as refigerator plug
needs to be a separate circuit.

It is perfectly legal to have the fridge on a 20a small appliance
circuit. It is only when you serve it from a 15a circuit that it must
be dedicated.

This is also a fairly recent rule(1996) . If you have an old house the
fridge might be on with just about anything. Prior to 96 you could
even have outdoor receptacles on the SA circuit.


But the "total remodel" would have required bringing the house totally
up to code. House was likely built with knob and tube. The fact there
are open grounds in several bedrooms would make me severely question
if the house was totally and properly rewired.

My guess? There is a LOT that is not up to code, and a lot of corners
were cut. Get a trustworthy electrician in there and have it checked
out. Two hours should tell the majority of the story and save you a
lot of expensive grief over what you don't know now.

Agreed. Very frustrating that it's so far away and I can't at least try
to troubleshoot this myself, with help from my a.h.r. pals. I contacted
the inspector and asked him for a referral to a good electrician. Our
inspection contingency expires in a few days.

Of course I'm eager to get an explanation of the fridge outlet anomaly,
but told the inspector I'd like to get the whole electrical system
looked over to see whether it's generally sound or a total disaster.

The bank already paid 3K to have the brand new master shower rebuilt
after the last prospective purchaser's inspector found water under the
house. So there were definitely some substandard parts of this project.

In article , bud--
wrote:

Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?


IMHO all 3 lights lit indicates voltage between each pair of wires.
Assuming the outlet is not connected to 220 that requires one wire,
probably ground, to be not be connected or be open back to the panel.

Post what you find Smitty.

Damned if I can visualize any combination of wiring problems that would
put 120 across each pair of wires, but that sure seems like the
indication...

In article , (Smitty Two) writes:

| Damned if I can visualize any combination of wiring problems that would
| put 120 across each pair of wires, but that sure seems like the
| indication...

My refrigerator outlet is on a multi-wire branch circuit with the washer.
An NM/3 from the fuse box enters the outlet box for the refrigerator where
one hot leg and neutral supply the outlet. An NM/2 continues the other hot
leg and neutral to the washer outlet. If the neutral were interrupted
anywhere between the fuse box and the refrigerator outlet and the washer
were on I would see voltage across each pair.

Dan Lanciani
ddl@danlan.*com

Andy comments:

If the outlet was wired for 220, then all three lights would be lit.
However, a 220 outlet is "supposed" to have a different
style of receptacle. Sometimes, someone takes a shortcut.

I don't know it this is your problem, but it is a reasonable
hypothesis.

Get a voltmeter and check it out before you plug in anything......

Andy in Eureka, Texas

Andy wrote:
Andy comments:

If the outlet was wired for 220, then all three lights would be lit.
However, a 220 outlet is "supposed" to have a different
style of receptacle. Sometimes, someone takes a shortcut.

I don't know it this is your problem, but it is a reasonable
hypothesis.

Get a voltmeter and check it out before you plug in anything......
....

Wouldn't seem very likely unless there were a pretty uncommon in the US
for home use nonstandard 240V fridge there before. But then it would
have taken a second hack to put a nonstandard plug on the cord as well.

I don't know the particular fault, either, but that one doesn't sound
like a particularly likely one to me...

--

Smitty Two wrote:
In article , bud--
wrote:

Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

IMHO all 3 lights lit indicates voltage between each pair of wires.
Assuming the outlet is not connected to 220 that requires one wire,
probably ground, to be not be connected or be open back to the panel.

Post what you find Smitty.

Damned if I can visualize any combination of wiring problems that would
put 120 across each pair of wires, but that sure seems like the
indication...

Doesn't have to be 120V, just enough to light the test lights. Assume
(probable) there is a test light between each pair of wires. If the
ground is completely open, 2 test lights are in series across 120V. They
will probably both light up (but not as bright as the 3rd light). Same
is true of an open neutral, but then the outlet would not ‘work’.

--
bud--

On Mon, 10 Nov 2008 09:12:35 -0600, bud--
wrote:

Smitty Two wrote:
In article , bud--
wrote:

Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

IMHO all 3 lights lit indicates voltage between each pair of wires.
Assuming the outlet is not connected to 220 that requires one wire,
probably ground, to be not be connected or be open back to the panel.

Post what you find Smitty.

Damned if I can visualize any combination of wiring problems that would
put 120 across each pair of wires, but that sure seems like the
indication...

Doesn't have to be 120V, just enough to light the test lights. Assume
(probable) there is a test light between each pair of wires. If the
ground is completely open, 2 test lights are in series across 120V. They
will probably both light up (but not as bright as the 3rd light). Same
is true of an open neutral, but then the outlet would not €˜work.
IF it is a NEON tester., it takes something like 70 to 92 vovlts to
fire. Under some circumstances they can remain lighted at about 50 -
70 volts . cAN ALSO FIRE due to "miller effect" - SOMETHING TO DO WITH
rf (WHICH WILL LIGHT AT A LOWER VOLTAGE) AND EXTERNAL CAPACITANCE. i'M
NO ENGINEER.

dpb wrote:
Andy wrote:
Andy comments:

If the outlet was wired for 220, then all three lights would be lit.
However, a 220 outlet is "supposed" to have a different
style of receptacle. Sometimes, someone takes a shortcut.

I don't know it this is your problem, but it is a reasonable
hypothesis.

Get a voltmeter and check it out before you plug in anything......
...

Wouldn't seem very likely unless there were a pretty uncommon in the US
for home use nonstandard 240V fridge there before. But then it would
have taken a second hack to put a nonstandard plug on the cord as well.

I don't know the particular fault, either, but that one doesn't sound
like a particularly likely one to me...

--
The outlets are different, but the cables can look the same. Back at
the breaker box, suppose the remodeler had the refrigerator cable
disconnected at the same time as a cable for an air-conditioner outlet.
A mix-up could mean 240V for the refrigerator and 120V for the air
conditioner.

Smitty Two wrote:
In article ,
Kevin Ricks wrote:

Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?
This happens when there is an open neutral elsewhere in the circuit AND
something else is connected to the same circuit and turned on. A
disconnected neutral at the panel would do this but the disconnect could
be anywhere along the line. The neutral between the outlet and other
load(s) would have to be intact.

Voltage is fed back though the other load, say the filament of a light
bulb, into the floating neutral and fooling the tester. The light would
be switched on but not glowing.

Did the inspector say something else was not working?

To get more accurate reading you would have to disconnect all other
loads from the circuit. Don't forget any direct wired appliances or
hidden things like a door bell transformer.

Note that using a volt meter in this case will give you the same crazy
readings. You will see 120V from hot to ground AND 120V from neutral to
ground. The 120V on neutral will go away when the other load(s) is
removed.

Kevin

I'm having a hard time visualizing what you're postulating. I made a
sketch of what I believe a circuit with a fridge and downstream load
would look like, but can't quite picture which wire(s) would be open to
cause the indication.

http://members.cox.net/prestwich/wiring.jpg

I suppose I'd have to start by asking whether my sketch is accurate.

The neutral would need to be open at 'c', or anywhere between the main
panel and 'c'

When there is no current in a load there is no voltage drop so voltage
at 'c' will be equal to the voltage at 'a'. (When measured with a volt
meter).
Neon bulbs act like a very high resistive load with very small current
flow so their effect is negligible.

So the neon bulb between a and e (Hot and Ground) will glow.
The neon bulb between c and e (Neutral and Ground will glow.
That will make the tester indicate normal AND hot neutral swap at the
same time.

The 3rd neon may glow dimly also depending on conditions and interaction
with the other neon bulbs.

If the load is switched off, all 3 may still glow but may be somewhat dim.

Kevin

Kevin Ricks wrote:


If the load is switched off, all 3 may still glow but may be somewhat dim.

Phantom voltage is likely to come from capacitance between the conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each read
40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground conductor
must have had 6.6Mohms capacitive reactance to each other conductor and
a total of 3.3Mohms capacitive reactance. (Actually, it would be lower
because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex cable
with the neutral disconnected at the breaker box and no appliances
connected to provide one of the bulbs in a tester with 120VAC and the
other two with 60 volts through approximately 3 million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see, but
the manufacturer of the tester could avoid the possibility by shunting
each neon bulb with a 100k resistor, or maybe even a million ohms.

E Z Peaces wrote:
Kevin Ricks wrote:


If the load is switched off, all 3 may still glow but may be somewhat
dim.

Phantom voltage is likely to come from capacitance between the conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each read
40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground conductor
must have had 6.6Mohms capacitive reactance to each other conductor and
a total of 3.3Mohms capacitive reactance. (Actually, it would be lower
because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex cable
with the neutral disconnected at the breaker box and no appliances
connected to provide one of the bulbs in a tester with 120VAC and the
other two with 60 volts through approximately 3 million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see, but
the manufacturer of the tester could avoid the possibility by shunting
each neon bulb with a 100k resistor, or maybe even a million ohms.


Phantom voltages can fool you when using a voltmeter, however in this
case, (Open neutral circuit with no other loads), you have 1 neon
directly connected between hot and ground -glows brightly.

The open neutral would make the other 2 neons be in series between hot
and ground. So they would in theory glow 1/2 bright. Now that I think
of it this is more likely the case for the OP. All 3 bulbs may glow in
both case (load or no load) but for different reasons.

Kevin




Kevin

Kevin Ricks wrote:
E Z Peaces wrote:
Kevin Ricks wrote:


If the load is switched off, all 3 may still glow but may be somewhat
dim.

Phantom voltage is likely to come from capacitance between the
conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each read
40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground conductor
must have had 6.6Mohms capacitive reactance to each other conductor
and a total of 3.3Mohms capacitive reactance. (Actually, it would be
lower because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex cable
with the neutral disconnected at the breaker box and no appliances
connected to provide one of the bulbs in a tester with 120VAC and the
other two with 60 volts through approximately 3 million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see,
but the manufacturer of the tester could avoid the possibility by
shunting each neon bulb with a 100k resistor, or maybe even a million
ohms.


Phantom voltages can fool you when using a voltmeter, however in this
case, (Open neutral circuit with no other loads), you have 1 neon
directly connected between hot and ground -glows brightly.

The open neutral would make the other 2 neons be in series between hot
and ground. So they would in theory glow 1/2 bright. Now that I think
of it this is more likely the case for the OP. All 3 bulbs may glow in
both case (load or no load) but for different reasons.

Kevin


Uh-oh! My calculations would apply if I were using one bulb to check
voltages sequentially, but a tester uses three bulbs at once. Doh!

Here's the link Smitty posted.
http://www.professionalequipment.com...productid=7918
I wonder how it's designed to show only one light with an open neutral.

E Z Peaces wrote:
Kevin Ricks wrote:
E Z Peaces wrote:
Kevin Ricks wrote:


If the load is switched off, all 3 may still glow but may be
somewhat dim.

Phantom voltage is likely to come from capacitance between the
conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each read
40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground
conductor must have had 6.6Mohms capacitive reactance to each other
conductor and a total of 3.3Mohms capacitive reactance. (Actually,
it would be lower because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex cable
with the neutral disconnected at the breaker box and no appliances
connected to provide one of the bulbs in a tester with 120VAC and the
other two with 60 volts through approximately 3 million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see,
but the manufacturer of the tester could avoid the possibility by
shunting each neon bulb with a 100k resistor, or maybe even a million
ohms.


Phantom voltages can fool you when using a voltmeter, however in this
case, (Open neutral circuit with no other loads), you have 1 neon
directly connected between hot and ground -glows brightly.

The open neutral would make the other 2 neons be in series between hot
and ground. So they would in theory glow 1/2 bright. Now that I think
of it this is more likely the case for the OP. All 3 bulbs may glow in
both case (load or no load) but for different reasons.

Kevin


Uh-oh! My calculations would apply if I were using one bulb to check
voltages sequentially, but a tester uses three bulbs at once. Doh!

Here's the link Smitty posted.
http://www.professionalequipment.com...productid=7918
I wonder how it's designed to show only one light with an open neutral.

Don't know for sure it could have other components maybe enough series
resistance to keep the other 2 bulbs off in an open neutral condition.
In my experience the other 2 neons will glow dimly and may not even be
noticed in bright lighting conditions. I once thought I had a bad tester
until found the fault and then thought about it. Now I disregard the dim
lit neons. My tester is 10 or 15 years old though.

Keep in mind though that these testers ware designed to test the
condition of the outlet they are IN, not the rest of the wiring.
There is a difference if the neutral wire is disconnected right at the
outlet or nearest pigtail connection and an open neutral on down the
line with other loads interfering. I think even the more sophisticated
testers would have a problem in that situation.

FYI - This page shows some diagrams of testers. This one works
differently than the commercially available units. The 3 lights stay on
for correct wiring and one or more of the lights go off with a fault
condition.
http://www.giangrandi.ch/electronics/neon/simple.html

Kevin

In article ,
E Z Peaces wrote:

Kevin Ricks wrote:
E Z Peaces wrote:
Kevin Ricks wrote:


If the load is switched off, all 3 may still glow but may be somewhat
dim.

Phantom voltage is likely to come from capacitance between the
conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each read
40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground conductor
must have had 6.6Mohms capacitive reactance to each other conductor
and a total of 3.3Mohms capacitive reactance. (Actually, it would be
lower because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex cable
with the neutral disconnected at the breaker box and no appliances
connected to provide one of the bulbs in a tester with 120VAC and the
other two with 60 volts through approximately 3 million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see,
but the manufacturer of the tester could avoid the possibility by
shunting each neon bulb with a 100k resistor, or maybe even a million
ohms.


Phantom voltages can fool you when using a voltmeter, however in this
case, (Open neutral circuit with no other loads), you have 1 neon
directly connected between hot and ground -glows brightly.

The open neutral would make the other 2 neons be in series between hot
and ground. So they would in theory glow 1/2 bright. Now that I think
of it this is more likely the case for the OP. All 3 bulbs may glow in
both case (load or no load) but for different reasons.

Kevin


Uh-oh! My calculations would apply if I were using one bulb to check
voltages sequentially, but a tester uses three bulbs at once. Doh!

Here's the link Smitty posted.
http://www.professionalequipment.com...productid=7918
I wonder how it's designed to show only one light with an open neutral.

I believe the tester is pretty simple; one bulb across H-N, one across
H-G, and one across N-G. Looking at the chart on the picture of the
unit, that seems like it would work in each of the listed cases.

The single bulb that's lit with an open neutral would be the one across
H-G.

Since one of the faults the tester is *designed* to show is an open
neutral, I'm skeptical that it could be fooled into showing three lights
of any intensity with an open neutral.

The electrician will be there tomorrow around noon, so I should have an
update soon.

Smitty Two wrote:
In article ,
E Z Peaces wrote:

Kevin Ricks wrote:
E Z Peaces wrote:
Kevin Ricks wrote:

If the load is switched off, all 3 may still glow but may be somewhat
dim.

Phantom voltage is likely to come from capacitance between the
conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each read
40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground conductor
must have had 6.6Mohms capacitive reactance to each other conductor
and a total of 3.3Mohms capacitive reactance. (Actually, it would be
lower because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex cable
with the neutral disconnected at the breaker box and no appliances
connected to provide one of the bulbs in a tester with 120VAC and the
other two with 60 volts through approximately 3 million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see,
but the manufacturer of the tester could avoid the possibility by
shunting each neon bulb with a 100k resistor, or maybe even a million
ohms.

Phantom voltages can fool you when using a voltmeter, however in this
case, (Open neutral circuit with no other loads), you have 1 neon
directly connected between hot and ground -glows brightly.

The open neutral would make the other 2 neons be in series between hot
and ground. So they would in theory glow 1/2 bright. Now that I think
of it this is more likely the case for the OP. All 3 bulbs may glow in
both case (load or no load) but for different reasons.

Kevin


Uh-oh! My calculations would apply if I were using one bulb to check
voltages sequentially, but a tester uses three bulbs at once. Doh!

Here's the link Smitty posted.
http://www.professionalequipment.com...productid=7918
I wonder how it's designed to show only one light with an open neutral.

I believe the tester is pretty simple; one bulb across H-N, one across
H-G, and one across N-G. Looking at the chart on the picture of the
unit, that seems like it would work in each of the listed cases.

The single bulb that's lit with an open neutral would be the one across
H-G.

Since one of the faults the tester is *designed* to show is an open
neutral, I'm skeptical that it could be fooled into showing three lights
of any intensity with an open neutral.

The electrician will be there tomorrow around noon, so I should have an
update soon.

Your explanation of the tester makes sense to me.

My guess is that back at the breaker box, the remodeler thought this was
the cable for a 240V window A/C and connected the black and white to the
terminals of a 240V breaker. Each would be 120V from the ground
terminal, but they would be 240V from each other because they are
opposite in phase.

Kevin Ricks wrote:
E Z Peaces wrote:
Kevin Ricks wrote:
E Z Peaces wrote:
Kevin Ricks wrote:


If the load is switched off, all 3 may still glow but may be
somewhat dim.

Phantom voltage is likely to come from capacitance between the
conductors.

A man used a Fluke 1507 to check voltage at the end of his new 50'
extension cord. He found 120V between hot and neutral, and each
read 40V from ground.

He thought the cord was defective. Then he remembered he'd used an
adapter, so his ground was open at the outlet.

Hot and neutral would have had the same capacitance to the ground
conductor, so without the meter in the circuit, the ground conductor
would have been 60V from each.

The meter has an input resistance of 3.0Mohms, so the ground
conductor must have had 6.6Mohms capacitive reactance to each other
conductor and a total of 3.3Mohms capacitive reactance. (Actually,
it would be lower because the meter would have a little capacitance.)

That would amount to about 8 picofarads per foot between each two
conductors in the cord. I suppose Romex would have roughly that much.

Using that cord as a model, I would expect an outlet on a Romex
cable with the neutral disconnected at the breaker box and no
appliances connected to provide one of the bulbs in a tester with
120VAC and the other two with 60 volts through approximately 3
million ohms.

I don't know if 60V through 3Mohms will light a bulb enough to see,
but the manufacturer of the tester could avoid the possibility by
shunting each neon bulb with a 100k resistor, or maybe even a
million ohms.


Phantom voltages can fool you when using a voltmeter, however in this
case, (Open neutral circuit with no other loads), you have 1 neon
directly connected between hot and ground -glows brightly.

The open neutral would make the other 2 neons be in series between
hot and ground. So they would in theory glow 1/2 bright. Now that I
think of it this is more likely the case for the OP. All 3 bulbs may
glow in both case (load or no load) but for different reasons.

Kevin


Uh-oh! My calculations would apply if I were using one bulb to check
voltages sequentially, but a tester uses three bulbs at once. Doh!

Here's the link Smitty posted.
http://www.professionalequipment.com...productid=7918
I wonder how it's designed to show only one light with an open neutral.

Don't know for sure it could have other components maybe enough series
resistance to keep the other 2 bulbs off in an open neutral condition.
In my experience the other 2 neons will glow dimly and may not even be
noticed in bright lighting conditions. I once thought I had a bad tester
until found the fault and then thought about it. Now I disregard the dim
lit neons. My tester is 10 or 15 years old though.

Keep in mind though that these testers ware designed to test the
condition of the outlet they are IN, not the rest of the wiring.
There is a difference if the neutral wire is disconnected right at the
outlet or nearest pigtail connection and an open neutral on down the
line with other loads interfering. I think even the more sophisticated
testers would have a problem in that situation.

FYI - This page shows some diagrams of testers. This one works
differently than the commercially available units. The 3 lights stay on
for correct wiring and one or more of the lights go off with a fault
condition.
http://www.giangrandi.ch/electronics/neon/simple.html

Kevin


Zeners! They could also be used to prevent bulbs from glowing in case
of an open connection, as in Smitty's link.

I wonder if the circuit in the link you posted has advantages over a
resistor-zener-zener-bulb in series between each pair of terminals.

In article ,
Smitty Two wrote:

So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

Thanks to all for participating in this puzzle. Here's what I finally
got from the electrician:

H-N 120 V
N-G 43 V
H-G 163 V

He said that the neutral wire was "bonded" to a ground wire of another
circuit in a junction box under the house, which was "backfeeding"
voltage to the fridge outlet. He did say the fridge was on a dedicated
circuit.

I don't know whether that makes sense to any of you, but it doesn't help
me much. I guess I don't have a thorough enough comprehension of the
electrical system to understand anomalies like that. To me, if you tie
neutral to ground, you get 0 volts across them.

I'm not 100% confident in his comprehension, either, based on his
statement that of the 120VAC in a house, 60 V comes in on the hot and
the other 60 comes in on the neutral. I've not heard that statement
before and don't know how looking at it that way would clarify anything.

While he was there he found and fixed a dead outlet, and two outlets
with switched hots and neutrals.

The ungrounded outlets in the one bedroom were attributed to original
(1930) wiring, the updating of which during an extensive remodel is
apparently required only by local code, which varies.

Other than that, he said the electrical system in general was in
reasonably good condition and not a concern.

Smitty Two wrote:
In article ,
Smitty Two wrote:

So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

Thanks to all for participating in this puzzle. Here's what I finally
got from the electrician:

H-N 120 V
N-G 43 V
H-G 163 V

He said that the neutral wire was "bonded" to a ground wire of another
circuit in a junction box under the house, which was "backfeeding"
voltage to the fridge outlet. He did say the fridge was on a dedicated
circuit.

I don't know whether that makes sense to any of you, but it doesn't help
me much. I guess I don't have a thorough enough comprehension of the
electrical system to understand anomalies like that. To me, if you tie
neutral to ground, you get 0 volts across them.

The problem seems to be the ground, not the neutral.

I don't know of any case where it is ok to bond a neutral and a ground
in a junction box. For safety, the ground conductor is supposed to go
all the way to the breaker box with no connection to any neutral.

Evidently the ground from the outlet goes to the neutral of a circuit
wired to the other 120V phase. It sounds as if the neutral of that
circuit must be open somewhere between that junction box and the neutral
bus in the breaker box.

43 volts sounds like leakage from a device on that other circuit, and
the device is not on. In that case, if that device were turned on, the
device would not work. H-N would remain at 120. N-G would be 120. H-G
would be 240.

To get rid of the bond between ground and neutral, it sounds as if the
circuit needs a cable with a ground between the junction box and the
breaker box. That other circuit may also need a modern cable.

On Nov 15, 7:43*pm, E Z Peaces wrote:
Smitty Two wrote:
In article ,
*Smitty Two wrote:

So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

Thanks to all for participating in this puzzle. Here's what I finally
got from the electrician:

H-N *120 V
N-G *43 V
H-G *163 V

He said that the neutral wire was "bonded" to a ground wire of another
circuit in a junction box under the house, which was "backfeeding"
voltage to the fridge outlet. He did say the fridge was on a dedicated
circuit.

I don't know whether that makes sense to any of you, but it doesn't help
me much. I guess I don't have a thorough enough comprehension of the
electrical system to understand anomalies like that. To me, if you tie
neutral to ground, you get 0 volts across them.

The problem seems to be the ground, not the neutral.

I don't know of any case where it is ok to bond a neutral and a ground
in a junction box. *For safety, the ground conductor is supposed to go
all the way to the breaker box with no connection to any neutral.

Evidently the ground from the outlet goes to the neutral of a circuit
wired to the other 120V phase. It sounds as if the neutral of that
circuit must be open somewhere between that junction box and the neutral
bus in the breaker box.

43 volts sounds like leakage from a device on that other circuit, and
the device is not on. *In that case, if that device were turned on, the
device would not work. *H-N would remain at 120. *N-G would be 120. *H-G
would be 240.

To get rid of the bond between ground and neutral, it sounds as if the
circuit needs a cable with a ground between the junction box and the
breaker box. *That other circuit may also need a modern cable.- Hide quoted text -

- Show quoted text -

use an old fashioned voltmeter like a Simpson 260 to make your
measurements. The new digital meters are so sensitve they can pick up
and register a voltage just because two wires are near each other even
though they are not actually connected. This can give a beginner
confusing readings. Or use a small 120V light bulb as a tester.
Mark

Mark wrote:
On Nov 15, 7:43 pm, E Z Peaces wrote:
Smitty Two wrote:
In article ,
Smitty Two wrote:
So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.
Any speculation on what could cause this unlisted and presumably
improbable test result?
Thanks to all for participating in this puzzle. Here's what I finally
got from the electrician:
H-N 120 V
N-G 43 V
H-G 163 V
He said that the neutral wire was "bonded" to a ground wire of another
circuit in a junction box under the house, which was "backfeeding"
voltage to the fridge outlet. He did say the fridge was on a dedicated
circuit.
I don't know whether that makes sense to any of you, but it doesn't help
me much. I guess I don't have a thorough enough comprehension of the
electrical system to understand anomalies like that. To me, if you tie
neutral to ground, you get 0 volts across them.
The problem seems to be the ground, not the neutral.

I don't know of any case where it is ok to bond a neutral and a ground
in a junction box. For safety, the ground conductor is supposed to go
all the way to the breaker box with no connection to any neutral.

Evidently the ground from the outlet goes to the neutral of a circuit
wired to the other 120V phase. It sounds as if the neutral of that
circuit must be open somewhere between that junction box and the neutral
bus in the breaker box.

43 volts sounds like leakage from a device on that other circuit, and
the device is not on. In that case, if that device were turned on, the
device would not work. H-N would remain at 120. N-G would be 120. H-G
would be 240.

To get rid of the bond between ground and neutral, it sounds as if the
circuit needs a cable with a ground between the junction box and the
breaker box. That other circuit may also need a modern cable.- Hide quoted text -

- Show quoted text -

use an old fashioned voltmeter like a Simpson 260 to make your
measurements. The new digital meters are so sensitve they can pick up
and register a voltage just because two wires are near each other even
though they are not actually connected. This can give a beginner
confusing readings. Or use a small 120V light bulb as a tester.
Mark


Now that I think about it, I agree with you that the 43 volts probably
comes from capacitive coupling between the neutral conductor to which
apparently the ground is (wrongly) bonded and the hot of that other
cable. If that other circuit gets its power from the other phase and
the neutral isn't continuous to the neutral bus and that cable is a lot
longer than the refrigerator cable, 43 volts sounds reasonable.

I agree that an old fashioned VOM can be handy in a case like this. At
the 250VAC range, mine has the same 1.25 megohms as a Simpson 260. In
this case I would expect a reading of about 5V if the voltage is coming
from capacitive coupling.

With proper wiring, resistance between N and G should be 10 million
times smaller than a Simpson 260. I don't see how any meter could find
voltage between them unless one is not wired properly back to the
breaker box.

E Z Peaces wrote:
Mark wrote:
On Nov 15, 7:43 pm, E Z Peaces wrote:
Smitty Two wrote:


- Show quoted text -

use an old fashioned voltmeter like a Simpson 260 to make your
measurements. The new digital meters are so sensitve they can pick up
and register a voltage just because two wires are near each other even
though they are not actually connected. This can give a beginner
confusing readings. Or use a small 120V light bulb as a tester.
Mark


Now that I think about it, I agree with you that the 43 volts probably
comes from capacitive coupling between the neutral conductor to which
apparently the ground is (wrongly) bonded and the hot of that other
cable. If that other circuit gets its power from the other phase and
the neutral isn't continuous to the neutral bus and that cable is a lot
longer than the refrigerator cable, 43 volts sounds reasonable.

I agree that an old fashioned VOM can be handy in a case like this. At
the 250VAC range, mine has the same 1.25 megohms as a Simpson 260. In
this case I would expect a reading of about 5V if the voltage is coming
from capacitive coupling.

With proper wiring, resistance between N and G should be 10 million
times smaller than a Simpson 260. I don't see how any meter could find
voltage between them unless one is not wired properly back to the
breaker box.

Old school usually works best in these situations. I sold
a lot of these back in the early 1970's:

http://www.mytoolstore.com/klein/69115.html

TDD

The Daring Dufas wrote:
E Z Peaces wrote:
Mark wrote:
On Nov 15, 7:43 pm, E Z Peaces wrote:
Smitty Two wrote:


- Show quoted text -

use an old fashioned voltmeter like a Simpson 260 to make your
measurements. The new digital meters are so sensitve they can pick up
and register a voltage just because two wires are near each other even
though they are not actually connected. This can give a beginner
confusing readings. Or use a small 120V light bulb as a tester.
Mark


Now that I think about it, I agree with you that the 43 volts probably
comes from capacitive coupling between the neutral conductor to which
apparently the ground is (wrongly) bonded and the hot of that other
cable. If that other circuit gets its power from the other phase and
the neutral isn't continuous to the neutral bus and that cable is a
lot longer than the refrigerator cable, 43 volts sounds reasonable.

I agree that an old fashioned VOM can be handy in a case like this.
At the 250VAC range, mine has the same 1.25 megohms as a Simpson 260.
In this case I would expect a reading of about 5V if the voltage is
coming from capacitive coupling.

With proper wiring, resistance between N and G should be 10 million
times smaller than a Simpson 260. I don't see how any meter could
find voltage between them unless one is not wired properly back to the
breaker box.

Old school usually works best in these situations. I sold
a lot of these back in the early 1970's:

http://www.mytoolstore.com/klein/69115.html

TDD

I would like to see a DMM with a light on a momentary switch to check a
circuit under a small load, like a solenoid tester. The old advantages,
price and durability, aren't so big these days as they were in 1913.

Solenoid testers have shortcomings. They show only approximate voltages
and can produce spikes in lines. Electricians used them to see if
circuits are energized, but they aren't foolproof. A hazardous voltage
could be below the tester's threshold. A voltage may be above the
threshold, but if it's coming through a high impedance, the load of the
tester may pull it below the threshold.

E Z Peaces wrote:

I would like to see a DMM with a light on a momentary switch to check a
circuit under a small load, like a solenoid tester.

Such an attachment would be easy to build using a stackable banana plug
pair, a switch, a lamp or power resistor and some epoxy putty to
encapsulate the whole thing.

Pete C. wrote:
E Z Peaces wrote:
I would like to see a DMM with a light on a momentary switch to check a
circuit under a small load, like a solenoid tester.

Such an attachment would be easy to build using a stackable banana plug
pair, a switch, a lamp or power resistor and some epoxy putty to
encapsulate the whole thing.

When meter leads had simple banana plugs, I could slide the plugs out a
couple of mm and stick a resistor between them.

On Nov 15, 2:33 pm, Smitty Two wrote:
In article ,
Smitty Two wrote:

So the g.f. and I are chipping in on a newly remodeled investment house
in her city, 300 miles from me. Home inspector sent a report that
included a notation that the outlet intended for the refrigerator is
giving an odd indication on the 3-LED tester: All three lights
illuminate.

Any speculation on what could cause this unlisted and presumably
improbable test result?

Thanks to all for participating in this puzzle. Here's what I finally
got from the electrician:

H-N 120 V
N-G 43 V
H-G 163 V

He said that the neutral wire was "bonded" to a ground wire of another
circuit in a junction box under the house, which was "backfeeding"
voltage to the fridge outlet. He did say the fridge was on a dedicated
circuit.

I don't know whether that makes sense to any of you, but it doesn't help
me much. I guess I don't have a thorough enough comprehension of the
electrical system to understand anomalies like that. To me, if you tie
neutral to ground, you get 0 volts across them.

I think this makes complete sense, actually. Sounds like someone's
tried to put in a grounded outlet for the fridge but was too lazy to
run new grounded cable all the way back to the panel. So they ran new
cable back to a junction box, tied it in to 2-wire that ran back to
the panel, and tried to fake a ground by tying ("bonded" is the
electrical code for "connected", especially when talking about ground)
the fridge ground to a neutral, on the common naive assumption that
since neutral and ground are bonded at one place, they must be
equivalent everywhere. But they didn't even use the neutral from the
same circuit! That's the little something extra that turns run-of-the-
mill lazy into fiendishly misguided.

I'm not 100% confident in his comprehension, either, based on his
statement that of the 120VAC in a house, 60 V comes in on the hot and
the other 60 comes in on the neutral. I've not heard that statement
before and don't know how looking at it that way would clarify anything.

Possibly that statement came out of an attempt at explaining why you
do get apparent voltage when you hook onto the neutral of a wire
carrying current. It's not a helpful way of looking at it. I'd be
confident of his comprehension, but not his articulateness.

While he was there he found and fixed a dead outlet, and two outlets
with switched hots and neutrals.

Which your original inspector's tester would have detected had he
bothered to plug it in . Perhaps the outlets were in use or hidden
when he was there.

The ungrounded outlets in the one bedroom were attributed to original
(1930) wiring, the updating of which during an extensive remodel is
apparently required only by local code, which varies.

Yes. If you want to put 3-prong outlets in those rooms, it is
acceptable to install GFCI receptacles, leaving the ground unconnected
(don't bond it to some convenient neutral!) and then affix the little
"no equipment ground" stickers that come with the CGFI for exactly
this purpose. Even if all your bedroom appliances are two-prong, the
old outlets will be loose, a possible arc danger, which can start
fires. The old boxes will be small by today's standards, but you can
probably get the GFCI's to fit. If there are no old boxes, you should
take the opportunity to install "old-work" boxes.

Other than that, he said the electrical system in general was in
reasonably good condition and not a concern.

I'd believe him, since there's no profit in it for him to say that.
I'd have him quote on the gfci replacements and running a few new
kitchen circuits. And re-doing the fridge circuit correctly, of
course.

Chip C
Toronto

In article ,
E Z Peaces wrote:
Pete C. wrote:
E Z Peaces wrote:
I would like to see a DMM with a light on a momentary switch to check a
circuit under a small load, like a solenoid tester.

Such an attachment would be easy to build using a stackable banana plug
pair, a switch, a lamp or power resistor and some epoxy putty to
encapsulate the whole thing.

When meter leads had simple banana plugs, I could slide the plugs out a
couple of mm and stick a resistor between them.


1: what difference did you notice on your measurements?

2: On what kind of situations?

3: And, what do you do NOW (no banana-plugs)?


Thanks,

David

On Tue, 16 Dec 2008 01:25:09 +0000 (UTC), (David
Combs) wrote:

In article ,
E Z Peaces wrote:
Pete C. wrote:
E Z Peaces wrote:
I would like to see a DMM with a light on a momentary switch to check a
circuit under a small load, like a solenoid tester.

Such an attachment would be easy to build using a stackable banana plug
pair, a switch, a lamp or power resistor and some epoxy putty to
encapsulate the whole thing.

When meter leads had simple banana plugs, I could slide the plugs out a
couple of mm and stick a resistor between them.


1: what difference did you notice on your measurements?

2: On what kind of situations?

3: And, what do you do NOW (no banana-plugs)?


Thanks,

David



I used to do the same - and phantom voltages dissapeared. Other than
that, nothing changed on low impedence circuits.

On Tue, 16 Dec 2008 01:25:09 +0000 (UTC), (David
Combs) wrote:

In article ,
E Z Peaces wrote:
Pete C. wrote:
E Z Peaces wrote:
I would like to see a DMM with a light on a momentary switch to check a
circuit under a small load, like a solenoid tester.

Such an attachment would be easy to build using a stackable banana plug
pair, a switch, a lamp or power resistor and some epoxy putty to
encapsulate the whole thing.

When meter leads had simple banana plugs, I could slide the plugs out a
couple of mm and stick a resistor between them.


1: what difference did you notice on your measurements?

2: On what kind of situations?

3: And, what do you do NOW (no banana-plugs)?


Thanks,

David




And what do I do NOW? I take a pair of test leads - with 'gator clamps
on both ends - and clip a resistor in with the clips fastened to the
test probes.