Kitchen Wiring Problem
mjb920
one for the dishwasher. There is one 12/3 cable coming out of the
slab. When I turn on either the breaker for the outlets or the breaker
for the dishwasher both the red and black wires go hot. Is the 12/3
wired wrong at the breaker box? Thanks for any help.
Jim
RicodJour
Two circuits run with the one cable.
R
Tony Hwang
You have a short or partial short down stream from breaker.
Use multi-meter for trouble-shooting
mm
How would a meter find it?
Doesn't he have to visually examine the cable looking for where the
short is, and then open the cable and separate the black and red.
Or do the whole cable like that until he gets to the part where the
short is? Then a meter would verify it, but it would be mostly the
looking at it and the splitting open.
RobertM
"mjb920" <mjb...@hotmail.com> wrote in message
news:1145939794.6...@u72g2000cwu.googlegroups.com...
Was it working ok before and then suddenly went bad or was it bad from
the time it was wired? Most shorts are near the ends and due to sloppy work.
Unusual for a good cable to suddenly go bad somewhere in the middle unless
someone drove a nail through it or a rat got to it.
Bob
mjb920
from the beginning. Right now we are in the middle of a kitchen
remodel, so I had to move a couple outlets. That's when I noticed that
both circuits were live even with only one breaker on. I am testing
the bare ends of the 12/3 at the cable sticking out of the wall, so I
don't see where any shorts would be, but I'll check for nails.
John Grabowski
> It was working before, but I am assuming that it was wired incorrectly
> from the beginning. Right now we are in the middle of a kitchen
> remodel, so I had to move a couple outlets. That's when I noticed that
> both circuits were live even with only one breaker on. I am testing
> the bare ends of the 12/3 at the cable sticking out of the wall, so I
> don't see where any shorts would be, but I'll check for nails.
>
Are you using a meter to test these wires? If you are, stop and use a
pigtail socket and a light bulb. You may be getting a false reading from
the meter.
Joseph Meehan
> It was working before, but I am assuming that it was wired incorrectly
> from the beginning. Right now we are in the middle of a kitchen
> remodel, so I had to move a couple outlets. That's when I noticed
> that both circuits were live even with only one breaker on. I am
> testing the bare ends of the 12/3 at the cable sticking out of the
> wall, so I don't see where any shorts would be, but I'll check for
> nails.
>
Is there 120 or 240 across the red and black?
--
Joseph Meehan
Dia duit
tra...@optonline.net
That should be easy to determine by inspection. If the cable is a
homerun straight to the kitchen, the most likely problems would be on
either end. It's possible a nail or similar was driven into the cable
somewhere along the way, but less likely.
Another key question. Apparently there is a GFCI breaker for one hot,
none for the other. Yet you have two hots, one for the dishwasher, one
for the outlets and just one neutral? This makes no sense, as the GFCI
can only work by comparing the current on the hot to the current on the
neutral. If the neutral was shared with another hot, then there would
be a current imbalance and the GFCI would always trip with the
dishwasher plus any load in one of the outlets. Something ain't right
here and may be the root of your problem.
Kevin Ricks
Has anything been changed recently such as an outlet replaced?
You have a shared neutral circuit. usually these types of circuits are used
on the dishwasher and disposal and normally the kitchen outlets would have
their own circuit(s). If you replace an outlet on this type of circuit then
you must remember to break off the tab between the 2 screws on the hot side.
At the panel both breakers should be next to each other and they should have
the handles tied together with some sort of clip. When both breakers are on
then you should measure 240V between the red and black. If they are not like
this then the neutral (white) could get overloaded.
Kevin
RayV
This makes no sense, as the GFCI can only work by comparing the current
on the hot to the current on the neutral.
Ray asked:
If the above is correct then why does a GFCI trip when you jump out the
nuetral and the ground?
RayV
I wouldn't think it is safe to connect 3 wire to the breaker box using
two breakers next to each other. As you said, you would end up with
240V potential at the end of the wire (pretty dangerous for the next
guy). I always run wires using a separate breaker for each piece of
wire(romex) unless it is a 240V circuit for range, AC, etc. The only
time I use 3 wire is for a 3 way switch circuit, ceiling fan or
something of that nature. Of course I'm not a licensed electrician,
just weekend warrior with a cool tool pouch.
tra...@optonline.net
By the above, I meant that for the GFCI to function, it has to be able
to compare the current flow on the hot to the current flow on the
neutral. That is exactly what it does and it will trip if they are not
equal. Hence, you can't have a GFCI share a neutral with another
circuit, which, if I understood it correctly, is what the OP says he
has.
GFCI's will also trip, as you pointed out, if the neutral and ground
are shorted, even without a load. They do that because they inject a
very small test current that they generate onto the hot and neutral.
If everything is proper downstream, then with no load connected, these
currents don't go anywhere. Short the neutral to ground, and then some
of the neutral current will return via the ground path, resulting in an
imbalance and trip, even with no load.
Doug Miller
>Is it ok to use 3 wire in this way?
Absolutely. As long as it's done properly, that is.
>
>I wouldn't think it is safe to connect 3 wire to the breaker box using
>two breakers next to each other. As you said, you would end up with
>240V potential at the end of the wire (pretty dangerous for the next
>guy).
You end up with 240V between the red and black, yes, but so what? It's no more
dangerous than a 240V circuit for a stove or a dryer.
And, in fact, it's *very* dangerous to *not* do it that way. If two circuits
share a neutral, the two hot wires *must* be on opposite legs of the 240V
service, and have a 240V potential between them. That way, the current in the
neutral wire is the *difference* of the currents in the two hot wires (e.g.
12A on the red wire and 17A on the black means 5A on the neutral). If,
instead, you put the two hot wires on the same leg of the service, the
potential between them is 0V and the current in the neutral wire is the *sum*
of the currents in the two hot wires: 12A on the red wire and 17A on the black
means 29A on the neutral, which overloads it and may cause a fire.
Google on "Edison circuit" for more information.
>I always run wires using a separate breaker for each piece of
>wire(romex) unless it is a 240V circuit for range, AC, etc. The only
>time I use 3 wire is for a 3 way switch circuit, ceiling fan or
>something of that nature. Of course I'm not a licensed electrician,
>just weekend warrior with a cool tool pouch.
For this application, you should use a 240V breaker also. That way, throwing
one breaker disconnects both hot legs simultaneously.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
RayV
tra...@optonline.net
>dangerous than a 240V circuit for a stove or a dryer.
I'm with Ray on this one. I think it is considerably more dangerous
than a 240V circuit for a stove or dryer. If you're working on a
circuit for a dryer or stove, one would expect there to be 240V between
two hots. But if I happen to be working on a std outlet, most people
would never expect there to be 240V between the two hots. For example,
I could see someone having things opened up for testing, and allowing
the two hots to touch each other, thinking they would be on the same
phase, which in every case that I have seen, they are.
Not saying you can;t do this, but anytime you start to deviate from
what is common or expected, you have to ask, is it worth it, just to
save another neutral run?
Sev
Kevin's suggestion of replaced outlet, if fixture or switch was
replaced and red and black wire nutted together. But this would imply
both are on same phase with previously noted overloaded neutral. Maybe
this island was a renovation, with wiring by non-electrician?
Bud--
Seems to me it is "common" and should be "expected". Looks like an
argument for calling an electrician.
If this is on 2 phases and 240V between hots I hope the comments of John
Grabowski weren't missed - test with a light bulb. A hot-to-hot short
would trip the breakers. If on the same phases - 120V between hots - it
is connected wrong and the neutral can overload.
bud--
Bud--
Zero volts between hots would be closer.
bud--
Doug Miller
>>You end up with 240V between the red and black, yes, but so what? It's no more
>>dangerous than a 240V circuit for a stove or a dryer.
>
>I'm with Ray on this one. I think it is considerably more dangerous
>than a 240V circuit for a stove or dryer. If you're working on a
>circuit for a dryer or stove, one would expect there to be 240V between
>two hots. But if I happen to be working on a std outlet, most people
>would never expect there to be 240V between the two hots.
If a circuit is fed by a double-pole breaker and has two hot wires, one red
and the other black, that would in fact be the normal assumption by someone
who understands residential wiring systems: that it's an Edison circuit, and
the potential between them is 240V. At a minimum, even to the uninformed it
should be a signal to check a little further to find out what's going on
before proceeding.
> For example,
>I could see someone having things opened up for testing, and allowing
>the two hots to touch each other, thinking they would be on the same
>phase, which in every case that I have seen, they are.
Allowing the two hots to touch is asking for trouble, regardless of the
type of circuit. Good practice, when opening up live circuits for testing, is
to make sure that *nothing* is touching anything else.
>
>Not saying you can;t do this, but anytime you start to deviate from
>what is common or expected, you have to ask, is it worth it, just to
>save another neutral run?
So who's suggesting deviating from the norm? This *is* a common situation.
It's "unexpected" only to those who are unfamiliar with Edison circuits.
tra...@optonline.net
Doug Miller wrote:
> In article <1145973552.2...@v46g2000cwv.googlegroups.com>, tra...@optonline.net wrote:
> >>You end up with 240V between the red and black, yes, but so what? It's no more
> >>dangerous than a 240V circuit for a stove or a dryer.
> >
> >I'm with Ray on this one. I think it is considerably more dangerous
> >than a 240V circuit for a stove or dryer. If you're working on a
> >circuit for a dryer or stove, one would expect there to be 240V between
> >two hots. But if I happen to be working on a std outlet, most people
> >would never expect there to be 240V between the two hots.
>
> If a circuit is fed by a double-pole breaker and has two hot wires, one red
> and the other black, that would in fact be the normal assumption by someone
> who understands residential wiring systems: that it's an Edison circuit, and
> the potential between them is 240V. At a minimum, even to the uninformed it
> should be a signal to check a little further to find out what's going on
> before proceeding.
>
> > For example,
> >I could see someone having things opened up for testing, and allowing
> >the two hots to touch each other, thinking they would be on the same
> >phase, which in every case that I have seen, they are.
>
> Allowing the two hots to touch is asking for trouble, regardless of the
> type of circuit. Good practice, when opening up live circuits for testing, is
> to make sure that *nothing* is touching anything else.
I agree that keeping everything isolated is what should be done. But
for average Joe homeowner, who would never think that there could be
240V between the two hots, I could see it happening.
> >
> >Not saying you can;t do this, but anytime you start to deviate from
> >what is common or expected, you have to ask, is it worth it, just to
> >save another neutral run?
>
> So who's suggesting deviating from the norm? This *is* a common situation.
> It's "unexpected" only to those who are unfamiliar with Edison circuits.
>
> --
It's not common in the sense that I've lived in many homes for many
years and I have never seen one. And if you asked the average
homeowner what an edison circuit or shared neutral is, virtually no one
would have a clue. Yet, it's common for homeowners to replace a wall
outlet or switch. If someone comes in this newgroup and asks how to do
that, I've never seen anyone suggest to be careful, it may be an edison
circuit or to verify that it's not being fed by dual breakers, perhaps
not linked or correctly identified.
And the point is why do this? All that is being saved is one lousy,
cheap neutral wire. I can see doing this if there is no easy way to do
it otherwise, eg old work, but I would never do it for new work.
As to the dangers of this practice, here, from the DOE:
http://www.eh.doe.gov/paa/oesummary/oesummary2005/oes2005-15-01.pdf
They discuss that shared neutrals circuits pose unique dangers if not
properly identifed and cite incidents that actually occurred. And
this is for industrial settings, where you can expect skilled workers,
not the average home, where Joe homeowner may be changing a switch.
Now you could say, but that's because they were not properly
identified. But why not just avoid it where possible all together?
RayV
nothing but con-artists and perverts.
Doug Miller
It's not relevant whether the potential is 240V or not: if you've opened up a
circuit for troubleshooting, that implies there is a fault somewhere. Possibly
that fault is a short somewhere downstream. Allowing the two hot wires to
touch will produce an arc; even 120V arc is plenty dangerous. If "average Joe
homeowner" doesn't have enough brains to keep everything separated while he's
probing voltage on live wires, he doesn't have any business touching the
stuff.
>> >
>> >Not saying you can;t do this, but anytime you start to deviate from
>> >what is common or expected, you have to ask, is it worth it, just to
>> >save another neutral run?
>>
>> So who's suggesting deviating from the norm? This *is* a common situation.
>> It's "unexpected" only to those who are unfamiliar with Edison circuits.
>It's not common in the sense that I've lived in many homes for many
>years and I have never seen one.
I've never seen a kangaroo, either, but I understand that they're pretty
common in some parts of the world. :-) -- the point being that it's sometimes
a mistake to generalize from one's own experiences, without recognizing the
limits of those experiences.
And I wouldn't be surprised if some of those homes had Edison circuits that
you weren't aware of. :-)
> And if you asked the average
>homeowner what an edison circuit or shared neutral is, virtually no one
>would have a clue.
The average homeowner doesn't work on his own electrical systems at all.
> Yet, it's common for homeowners to replace a wall
>outlet or switch. If someone comes in this newgroup and asks how to do
>that, I've never seen anyone suggest to be careful, it may be an edison
>circuit or to verify that it's not being fed by dual breakers, perhaps
>not linked or correctly identified.
You're making the same mistake again: generalizing from limited experiences.
I *have* seen that response here in this group, when someone went to replace
an outlet and found black, white, _and_red_ wires when he was expecting to
find only black and white, and asked what the extra wire was.
>And the point is why do this? All that is being saved is one lousy,
>cheap neutral wire.
You haven't priced copper wire lately, have you? :-)
It saves not only a neutral but a ground as well. A piece of 12/3 has four
wires in it; two pieces of 12/2 have six. A length of 12/3 is a *bunch*
cheaper than twice that length of 12/2.
Voltage drop is reduced, which may be an issue on long runs.
It's also less labor to run one cable vs. two.
And it uses half as many Romex connectors in junction boxes.
It also reduces the number of conductors in each junction box, allowing the
electrician to meet Code with smaller boxes (and possibly turning a
non-Code-compliant overfilled box into a compliant installation).
Ditto for the number of conductors in conduits.
In other words, you're making hasty generalizations again... just because you
can't imagine any reasons other than saving one neutral conductor, you assume
that there aren't any.
Not a correct assumption, I'm afraid.
> I can see doing this if there is no easy way to do
>it otherwise, eg old work, but I would never do it for new work.
Then don't do it. But understand that your reasons for criticizing it are not
valid.
>As to the dangers of this practice, here, from the DOE:
>
>http://www.eh.doe.gov/paa/oesummary/oesummary2005/oes2005-15-01.pdf
>
>They discuss that shared neutrals circuits pose unique dangers if not
>properly identifed and cite incidents that actually occurred.
Stop the presses! It's just been discovered that electricity can be dangerous!
Seriously, though -- _every_one_ of the incidents cited is traced to improper
installation or documentation. You draw the same erroneous conclusion as the
authors of the report state in the first paragraph: that shared neutrals are
dangerous. This is not correct: the danger comes from improper installation. A
properly installed shared neutral circuit is perfectly safe.
> And
>this is for industrial settings, where you can expect skilled workers,
>not the average home, where Joe homeowner may be changing a switch.
If it's been properly installed (using a two-pole breaker) it doesn't make any
difference whether the guy changing the switch is "Joe Homeowner Who Barely
Knows What He's Doing" or "Joe Licensed Electrician with Forty Years
Experience in the Trade" -- flipping *one* breaker kills the *entire* circuit,
just the same as with a normal 120V circuit.
>Now you could say, but that's because they were not properly
>identified.
No, it's because they were not properly *installed*, with a *single* means of
disconnecting *all* of the hot conductors. And in at least one of the cases
cited in that report, the energized neutral was apparently due to an incorrect
connection to hot conductors -- improper installation again.
> But why not just avoid it where possible all together?
You're certainly free to avoid it if you wish. But to advise others to avoid
it, on the basis of phantom hazards that you perceive largely due to your own
unfamiliarity with it, is not logical.
--
tra...@optonline.net
Geez, you now think I'm so stupid I wouldn't recognize a double breaker
in the panel? The only double breakers I have ever seen in my homes
or other homes I've been involved with were for std 240V loads, ie
dryer, stove, A/C. There were no other double breakers for shared
neutral 120V circuits. If these were common, I would think you;d see
a hell of a lot of people showing up in the newsgroup to ask what
these double breakers were for every day. Yeah, one comes up once in a
while, but if they were all that common, I'd be expecting them all the
time, cause people would wonder what they had. I'd be interested in
hearing from other folks as to how common they think a shared neutral
circuit is.
>
> > And if you asked the average
> >homeowner what an edison circuit or shared neutral is, virtually no one
> >would have a clue.
>
> The average homeowner doesn't work on his own electrical systems at all.
Again, give me a break. It's very common for a homeowner to replace a
switch or outlet themselves. Not all do, but for a guy claiming edison
circuits are common and well known by everyone, it's pretty bizarre to
be arguing that it's not common for a homeowner to replace a wall
switch.
>
> > Yet, it's common for homeowners to replace a wall
> >outlet or switch. If someone comes in this newgroup and asks how to do
> >that, I've never seen anyone suggest to be careful, it may be an edison
> >circuit or to verify that it's not being fed by dual breakers, perhaps
> >not linked or correctly identified.
>
> You're making the same mistake again: generalizing from limited experiences.
> I *have* seen that response here in this group, when someone went to replace
> an outlet and found black, white, _and_red_ wires when he was expecting to
> find only black and white, and asked what the extra wire was.
>
> >And the point is why do this? All that is being saved is one lousy,
> >cheap neutral wire.
>
> You haven't priced copper wire lately, have you? :-)
I don't think I'm the one who needs to do pricing. You can get 14/2
Romex for .20 a foot. 14/3 is about .30. So for a whopping 50 ft run,
if you do it with 14/3, it's $15.00 for wire. Run two 14/2 cables and
it's $20.00.
Are you arguing that $5.00 is a big deal? Even if it were double or
triple who the hell cares?
Can't a
>
> It saves not only a neutral but a ground as well. A piece of 12/3 has four
> wires in it; two pieces of 12/2 have six. A length of 12/3 is a *bunch*
> cheaper than twice that length of 12/2.
Oh really, $5 is a bunch cheaper?
>
> Voltage drop is reduced, which may be an issue on long runs.
>
> It's also less labor to run one cable vs. two.
>
> And it uses half as many Romex connectors in junction boxes.
>
> It also reduces the number of conductors in each junction box, allowing the
> electrician to meet Code with smaller boxes (and possibly turning a
> non-Code-compliant overfilled box into a compliant installation).
>
> Ditto for the number of conductors in conduits.
>
> In other words, you're making hasty generalizations again... just because you
> can't imagine any reasons other than saving one neutral conductor, you assume
> that there aren't any.
I never said there weren't valid reasons for doing it if you have to.
In fact, I even stated, it could make sense for old work, where there
is no easy alternative. And most of what you cited above, applies to
old work, because in new work, the number or size of boxes ain;t a big
deal. So, thanks for telling me what I already stated. Again, I'd
like to hear from others that have seen shared neutrals commonly used
in new construction.
>
> Not a correct assumption, I'm afraid.
>
> > I can see doing this if there is no easy way to do
> >it otherwise, eg old work, but I would never do it for new work.
>
> Then don't do it. But understand that your reasons for criticizing it are not
> valid.
>
> >As to the dangers of this practice, here, from the DOE:
> >
> >http://www.eh.doe.gov/paa/oesummary/oesummary2005/oes2005-15-01.pdf
> >
> >They discuss that shared neutrals circuits pose unique dangers if not
> >properly identifed and cite incidents that actually occurred.
>
> Stop the presses! It's just been discovered that electricity can be dangerous!
>
> Seriously, though -- _every_one_ of the incidents cited is traced to improper
> installation or documentation. You draw the same erroneous conclusion as the
> authors of the report state in the first paragraph: that shared neutrals are
> dangerous. This is not correct: the danger comes from improper installation. A
> properly installed shared neutral circuit is perfectly safe.
Yeah, I new this was coming. The DOE is wrong too. The point is if
it's easier to make something safer and easier to work on by not
sharing neutrals, and it only costa a few extra bucks, some of us would
prefer to do it that way. This is like arguing that hydrogen
dirrigibles are safe, you just have to keep them away from lightning
and use them properly.
>
> > And
> >this is for industrial settings, where you can expect skilled workers,
> >not the average home, where Joe homeowner may be changing a switch.
>
> If it's been properly installed (using a two-pole breaker) it doesn't make any
> difference whether the guy changing the switch is "Joe Homeowner Who Barely
> Knows What He's Doing" or "Joe Licensed Electrician with Forty Years
> Experience in the Trade" -- flipping *one* breaker kills the *entire* circuit,
> just the same as with a normal 120V circuit.
>
> >Now you could say, but that's because they were not properly
> >identified.
>
> No, it's because they were not properly *installed*, with a *single* means of
> disconnecting *all* of the hot conductors. And in at least one of the cases
> cited in that report, the energized neutral was apparently due to an incorrect
> connection to hot conductors -- improper installation again.
>
>
> > But why not just avoid it where possible all together?
>
> You're certainly free to avoid it if you wish. But to advise others to avoid
> it, on the basis of phantom hazards that you perceive largely due to your own
> unfamiliarity with it, is not logical.
The hazards are not phantom, but real andl documented and recognized by
the DOE. But then you think they are wrong too.
volts500
> Geez, you now think I'm so stupid I wouldn't recognize a double breaker
> in the panel? The only double breakers I have ever seen in my homes
> or other homes I've been involved with were for std 240V loads, ie
> dryer, stove, A/C. There were no other double breakers for shared
> neutral 120V circuits.
That's because a double breaker is not required by NEC unless the
outlets for the circuits are on the same yoke, such as a duplex outlet
with the hot side tab removed and fed with a 12/3 w ground.
> If these were common, I would think you;d see
> a hell of a lot of people showing up in the newsgroup to ask what
> these double breakers were for every day. Yeah, one comes up once in a
> while, but if they were all that common, I'd be expecting them all the
> time, cause people would wonder what they had. I'd be interested in
> hearing from other folks as to how common they think a shared neutral
> circuit is.
> I never said there weren't valid reasons for doing it if you have to.
> In fact, I even stated, it could make sense for old work, where there
> is no easy alternative. And most of what you cited above, applies to
> old work, because in new work, the number or size of boxes ain;t a big
> deal.
Then, no offense, but you probably don't do much new electric
construction, because very few inspected electrical installations will
pass unless the box fill is right.
> So, thanks for telling me what I already stated. Again, I'd
> like to hear from others that have seen shared neutrals commonly used
> in new construction.
As an electrician, I use them almost every day, especially in
commercial and industrial work. In fact, try using one "neutral" for
each hot on a commercial job and you'll get laughed off the job in a
hurry, if not fired. The practice of using Edison circuits in
residential wiring, IIRC, became common in the WWII era to save on
copper. The practice is still common in residential wiring to this
day. Now that the price of copper is though the roof there is no doubt
that more Edison circuits will be used in new residential construction.
Doug Miller
>
>Doug Miller wrote:
>> And I wouldn't be surprised if some of those homes had Edison circuits that
>> you weren't aware of. :-)
>
>Geez, you now think I'm so stupid I wouldn't recognize a double breaker
>in the panel? The only double breakers I have ever seen in my homes
>or other homes I've been involved with were for std 240V loads, ie
>dryer, stove, A/C. There were no other double breakers for shared
>neutral 120V circuits.
NEC doesn't require double breakers unless both circuits supply a common
device. Using a double breaker is still prudent practice, but not all Edison
circuits will have them. Hence it's fairly easy to be unaware of having Edison
circuits unless you open up the panel and see the red wires.
> If these were common, I would think you;d see
>a hell of a lot of people showing up in the newsgroup to ask what
>these double breakers were for every day. Yeah, one comes up once in a
>while, but if they were all that common, I'd be expecting them all the
>time, cause people would wonder what they had. I'd be interested in
>hearing from other folks as to how common they think a shared neutral
>circuit is.
>
>
>
>>
>> > And if you asked the average
>> >homeowner what an edison circuit or shared neutral is, virtually no one
>> >would have a clue.
>>
>> The average homeowner doesn't work on his own electrical systems at all.
>
>Again, give me a break. It's very common for a homeowner to replace a
>switch or outlet themselves. Not all do, but for a guy claiming edison
>circuits are common and well known by everyone, it's pretty bizarre to
>be arguing that it's not common for a homeowner to replace a wall
>switch.
Don't put words in my mouth. I never said they were well known by everyone. I
contradicted your claim that they were a deviation from "what is common or
expected."
>>
>> > Yet, it's common for homeowners to replace a wall
>> >outlet or switch. If someone comes in this newgroup and asks how to do
>> >that, I've never seen anyone suggest to be careful, it may be an edison
>> >circuit or to verify that it's not being fed by dual breakers, perhaps
>> >not linked or correctly identified.
>>
>> You're making the same mistake again: generalizing from limited experiences.
>> I *have* seen that response here in this group, when someone went to replace
>> an outlet and found black, white, _and_red_ wires when he was expecting to
>> find only black and white, and asked what the extra wire was.
>>
>> >And the point is why do this? All that is being saved is one lousy,
>> >cheap neutral wire.
>>
>> You haven't priced copper wire lately, have you? :-)
>
>I don't think I'm the one who needs to do pricing. You can get 14/2
>Romex for .20 a foot. 14/3 is about .30. So for a whopping 50 ft run,
>if you do it with 14/3, it's $15.00 for wire. Run two 14/2 cables and
>it's $20.00.
IOW using an Edison circuit saves 25% on the cost of wire.
>Are you arguing that $5.00 is a big deal? Even if it were double or
>triple who the hell cares?
To anyone who actually does a lot of wiring, fifty feet is a pretty short run
(not "whopping"), and a 25% saving on the cost of wire is important.
>>
>> It saves not only a neutral but a ground as well. A piece of 12/3 has four
>> wires in it; two pieces of 12/2 have six. A length of 12/3 is a *bunch*
>> cheaper than twice that length of 12/2.
>
>Oh really, $5 is a bunch cheaper?
25% savings is a bunch, yes.
>
>>
>> Voltage drop is reduced, which may be an issue on long runs.
>>
>> It's also less labor to run one cable vs. two.
>>
>> And it uses half as many Romex connectors in junction boxes.
>>
>> It also reduces the number of conductors in each junction box, allowing the
>> electrician to meet Code with smaller boxes (and possibly turning a
>> non-Code-compliant overfilled box into a compliant installation).
>>
>> Ditto for the number of conductors in conduits.
>>
>> In other words, you're making hasty generalizations again... just because you
>> can't imagine any reasons other than saving one neutral conductor, you assume
>> that there aren't any.
>
>
>I never said there weren't valid reasons for doing it if you have to.
The hell you didn't. You said:
> I can see doing this if there is no easy way to do
>it otherwise, eg old work, but I would never do it for new work.
>In fact, I even stated, it could make sense for old work, where there
>is no easy alternative.
It makes sense for new work, too.
> And most of what you cited above, applies to
>old work, because in new work, the number or size of boxes ain;t a big
>deal.
Nonsense. Conduit fill and junction box fill are considerations for *new*
work much more so than old, because in old work the conduit and boxes are
already in place.
Voltage drop and labor savings on running cable are equally issues in new or
old work.
>So, thanks for telling me what I already stated.
Actually I told you the exact *opposite* of what you already stated: that
there are many valid reasons for using Edison circuits. Not my fault if you
don't understand those reasons.
> Again, I'd
>like to hear from others that have seen shared neutrals commonly used
>in new construction.
>
>
>>
>> Not a correct assumption, I'm afraid.
>>
>> > I can see doing this if there is no easy way to do
>> >it otherwise, eg old work, but I would never do it for new work.
>>
>> Then don't do it. But understand that your reasons for criticizing it are not
>> valid.
>>
>> >As to the dangers of this practice, here, from the DOE:
>> >
>> >http://www.eh.doe.gov/paa/oesummary/oesummary2005/oes2005-15-01.pdf
>> >
>> >They discuss that shared neutrals circuits pose unique dangers if not
>> >properly identifed and cite incidents that actually occurred.
>>
>> Stop the presses! It's just been discovered that electricity can be
> dangerous!
>>
>> Seriously, though -- _every_one_ of the incidents cited is traced to improper
>> installation or documentation. You draw the same erroneous conclusion as the
>> authors of the report state in the first paragraph: that shared neutrals are
>> dangerous. This is not correct: the danger comes from improper installation.
> A
>> properly installed shared neutral circuit is perfectly safe.
>
>
>Yeah, I new this was coming. The DOE is wrong too.
Read the article again. I think you missed the point in a few places.
Throughout, the hazards described are the result of improper installation
and/or improper documentation of what was installed. The conclusion that the
hazard is the type of circuit installed, rather than the acknowledged failure
to install it correctly, is not supported by the evidence presented -- in
fact, the evidence directly contradicts it.
>The point is if
>it's easier to make something safer and easier to work on by not
>sharing neutrals, and it only costa a few extra bucks, some of us would
>prefer to do it that way.
You're still missing the point. A properly installed Edison circuit is no less
safe to work on than any other circuit. You're perfectly free to not use them
if you have trouble understanding them, but stop claiming they're less safe.
They're not.
> This is like arguing that hydrogen
>dirrigibles are safe, you just have to keep them away from lightning
>and use them properly.
Poor analogy: a hydrogen dirigible is inherently unsafe in the presence of
common hazards, whereas a properly installed Edison circuit is not.
>>
>> > And
>> >this is for industrial settings, where you can expect skilled workers,
>> >not the average home, where Joe homeowner may be changing a switch.
>>
>> If it's been properly installed (using a two-pole breaker) it doesn't make
> any
>> difference whether the guy changing the switch is "Joe Homeowner Who Barely
>> Knows What He's Doing" or "Joe Licensed Electrician with Forty Years
>> Experience in the Trade" -- flipping *one* breaker kills the *entire*
> circuit,
>> just the same as with a normal 120V circuit.
>>
>> >Now you could say, but that's because they were not properly
>> >identified.
>>
>> No, it's because they were not properly *installed*, with a *single* means of
>> disconnecting *all* of the hot conductors. And in at least one of the cases
>> cited in that report, the energized neutral was apparently due to an
> incorrect
>> connection to hot conductors -- improper installation again.
>>
>>
>> > But why not just avoid it where possible all together?
>>
>> You're certainly free to avoid it if you wish. But to advise others to avoid
>> it, on the basis of phantom hazards that you perceive largely due to your own
>> unfamiliarity with it, is not logical.
>
>
>The hazards are not phantom, but real andl documented and recognized by
>the DOE. But then you think they are wrong too.
Like I said, you need to read the article more carefully. The hazards
documented there are hazards of improper installation and improper circuit
marking.
mark
"volts500" <volt...@aol.com> wrote in message
news:1146004271....@j33g2000cwa.googlegroups.com...
ditto see it and do it all the time.Just did it in my spare bedroom
{workroom} 4 hots 2 neutrals.pulled a ground but its not really needed
...its in pipe.Pig tail the neutrals at the outlets and good to go.
mjb920
the GFI circuit breaker turns on the black and the dishwasher circuit
breaker turns on the red. 240 volts across the red and black; 120
volts across the red and neutral and the black and neutral. Thanks!
Tony Hwang
Kitchen couter top duplex receptacles have two separate circuit feeding
each plug in. You have to break the link to separate those two
receptacles to be fed separately. Wonder if mistake is made here.
RayV
That's because a double breaker is not required by NEC unless the
outlets for the circuits are on the same yoke, such as a duplex outlet
with the hot side tab removed and fed with a 12/3 w ground.
Do you mean by this that the top of the outlet would be powered by the
red and the bottom of the outlet would be powered by the black. If
not, I don't understand why you would need to remove the tab.
RayV
he had with an electrician a while back. The electrician told him that
he sometimes does these circuits but "would always put the breakers on
the 1 & 5 or some other combination so that you couldn't get 240V". My
brother asked the guy about overloading the nuetral and the electrician
told him "you don't have to worry about that as long as the breakers
are good".
Yes, this guy was a licensed electrician that works residential
construction. So I restate my opinion that I don't think it's a good
idea because the next guy (weekend warrior) might only know enough to
get himself hurt.
Doug Miller
>Not that I'm going to try this but you said:
>
>That's because a double breaker is not required by NEC unless the
>outlets for the circuits are on the same yoke, such as a duplex outlet
>with the hot side tab removed and fed with a 12/3 w ground.
>
>Do you mean by this that the top of the outlet would be powered by the
>red and the bottom of the outlet would be powered by the black.
That's it exactly.
>If not, I don't understand why you would need to remove the tab.
If not, you don't need to remove the tab -- in fact, you need to leave it in
place.
Doug Miller
>I asked my brother about this today and he told me about a discussion
>he had with an electrician a while back. The electrician told him that
>he sometimes does these circuits but "would always put the breakers on
>the 1 & 5 or some other combination so that you couldn't get 240V". My
>brother asked the guy about overloading the nuetral and the electrician
>told him "you don't have to worry about that as long as the breakers
>are good".
He's wrong. Dangerously wrong.
>
>Yes, this guy was a licensed electrician that works residential
>construction.
I wonder if he really does have a license... or just claims to. I used to live
in a county that had *no* licensing requirement for electricians. Any idiot
who wanted to, could call himself an "electrician" and go into business.
Perhaps this guy is that type of "electrician".
> So I restate my opinion that I don't think it's a good
>idea because the next guy (weekend warrior) might only know enough to
>get himself hurt.
Put it on a double-pole breaker, and it's perfectly safe.
tra...@optonline.net
Doug Miller wrote:
> In article <1145997918.6...@j33g2000cwa.googlegroups.com>, tra...@optonline.net wrote:
> >
> >Doug Miller wrote:
> >> And I wouldn't be surprised if some of those homes had Edison circuits that
> >> you weren't aware of. :-)
> >
> >Geez, you now think I'm so stupid I wouldn't recognize a double breaker
> >in the panel? The only double breakers I have ever seen in my homes
> >or other homes I've been involved with were for std 240V loads, ie
> >dryer, stove, A/C. There were no other double breakers for shared
> >neutral 120V circuits.
>
> NEC doesn't require double breakers unless both circuits supply a common
> device. Using a double breaker is still prudent practice, but not all Edison
> circuits will have them. Hence it's fairly easy to be unaware of having Edison
> circuits unless you open up the panel and see the red wires.
And this is exactly the type of thing that lead to the incidents in the
DOE report I cited, where shared neutral circuits were not IDENTIFIED,
leading to people being shocked.
They're having a sale at the HD store 25 miles away for 25% off a $2
item. You're gonna save 25%, which is a bunch. Drop everything
and get in the truck and go save your 50 cents. LOL Bet you can
save another penny, by not putting staples in a cable on a job where it
really should have one to be done right, but you figure it can pass
anyway! Or save more by using the cheapest materials you can get away.
Bud--
the possible hazards of COMMON electrical wiring, and that only licenced
electricians should work on line voltage circuits. Maybe you could
discuss doorbells and I might extend that to low voltage.
bud--
RayV
Ray gratefully replied:
Thank you for you permission to *maybe* discuss doorbells.
Since I am fairly new to newsgroups could you share some of your
infinitely superior intellect and explain how I get permission to
discuss doorbells?
Is there a form I need to fill out?
Do licensed electricians need to divest themselves of real property
like a priest or a nun to gain this superior intellect?
I ask because you said, "homeowners are not smart enough to
understand the possible hazards of COMMON electrical wiring"
therefore, a licensed electrician is too smart to be a homeowner?
Bud--
> Bud said:
>
> "You have convinced me that homeowners are not smart enough to
> understand the possible hazards of COMMON electrical wiring, and that
> only licenced electricians should work on line voltage circuits. Maybe
> you could discuss doorbells and I might extend that to low voltage."
>
> Ray gratefully replied:
> Thank you for you permission to *maybe* discuss doorbells.
>
> Since I am fairly new to newsgroups could you share some of your
> infinitely superior intellect and explain how I get permission to
> discuss doorbells?
>
> Is there a form I need to fill out?
>
I never said permission was required to discuss doorbells.
> Do licensed electricians need to divest themselves of real property
> like a priest or a nun to gain this superior intellect?
> I ask because you said, "homeowners are not smart enough to
> understand the possible hazards of COMMON electrical wiring"
> therefore, a licensed electrician is too smart to be a homeowner?
>
Some may have detected a note of sarcasm toward a specific poster on the
issue of multiwire branch circuits. But let me take another tack.
1. At least 3 electricians have said multiwire branch circuits are
commonly used and may be expected to be found (as opposed to a specific
poster).
2. None of the electricians has expressed a fear of bodily harm from
multiwires.
3. The National Electrical Code permits multiwire branch circuits.
4. The NEC is a pragmatic code and is sensitive to masses of dead bodies
- must have been none from multiwires.
5. Bodies of homeowners in this case might be taken as an example of
natural selection.
bud--
tra...@optonline.net
Since some of you think I'm the only one that sees problems in shared
neutrals in homes, here's a tech bulletin from Square D, a company that
ought to know a bit more about the issue than most of us here. Not
only do they discuss the significant disadvantages of shared neutrals,
including the safety issues, they go on to dismiss the cost savings as
being a red herring, and clearly consider it something that should be
avoided, if possible. In fact, their position is remarkably similar
to exactly what I've been saying:
Shared Neutrals in Residential Wiring
Class 760
Retain for future use.
© 2002 Schneider Electric All Rights Reserved
Shared Neutrals in Residential Wiring 0760DB0203R902
Data Bulletin 10/2002
2
Disadvantages of Shared Neutrals There are several significant
disadvantages to be found in the practice of
sharing neutrals:
· On two-pole common-trip circuit breakers, both circuits are
interrupted
during any type of fault. If a shared neutral circuit feeds many rooms,
then all rooms lose power if a fault occurs in any one room. If a
shared
neutral circuit feeds receptacles and lights, both will lose power with
a
fault on either one.
· If the homerun neutral is lost, the connected loads are subject to
voltages varying from 0 V to 240 V (line-to-line). The likely result
from this is severe damage to any connected devices due to extreme
under- and over-voltage conditions.
· On two-pole independent-trip circuit breakers, one may find hot
wires
in a junction box that was presumed dead. One cannot overemphasize
how dangerous this would be. If one of the shared neutral circuits were
to
trip due to a short-circuit or overload, the other circuit would remain
hot.
Anyone servicing any device in that junction box may be exposed to
live conductors.
Moving Forward There is a need for the two-pole device in retrofit and
240 V applications. As
code requirements expand to these applications, Square D will offer a
120/240 V two-pole device. It will be specifically intended for 240 V
and
shared neutral applications, where shared neutrals exist and running
new
cable is not practical.
Before understanding all of the facts, one may believe that sharing
neutrals
is economical. The savings, if any, are not as large as one may think.
In a
typical residential application, two 75-foot-long (22.8 m) home runs
could be
wired with one cable, instead of two, by sharing neutrals. The typical
cost of
the three-conductor cable is about twice that of the two-conductor
cable.
Thus the money saved in cable cost is negligible. Compared to two
one-pole
AFCIs, the cost of a two-pole AFCI is only slightly higher.
To reduce the difficulties found in pulling two cables for the homerun
rather
than one, several cable and wire manufacturers have introduced new
fourconductor
plus ground cables. These new cables offer independent neutrals,
thus eliminating the potential problems associated with shared
neutrals.
For more information about the disadvantages of shared neutrals, call
Square D Cedar Rapids Application Support at (319) 369-6650.
Electrical equipment should be installed, operated, serviced, and
maintained only by
qualified personnel. No responsibility is assumed by Schneider Electric
for any
consequences arising out of the use of this material.
Square D Company
3700 Sixth St. SW
Cedar Rapids, IA 52404 USA
1-888-SquareD (1-888-778-2733)
www.SquareD.com
volts500
The NEC does not required two pole breakers for multi-wire circuits
unless they feed a device where both are on the same yoke., as
previously discussed. The point is mute.
> · If the homerun neutral is lost, the connected loads are subject to
> voltages varying from 0 V to 240 V (line-to-line). The likely result
> from this is severe damage to any connected devices due to extreme
> under- and over-voltage conditions.
That's why NEC requires the neutral to be made up continuous
(pigtailed) on all multi-wire circuits. `Additionally, the "hazard"
still exists at the main service, since it's 3-wire, losing the neutral
jeapordizes the entire house, not just two circuits with a shared
neutral.
> · On two-pole independent-trip circuit breakers, one may find hot
> wires
> in a junction box that was presumed dead. One cannot overemphasize
> how dangerous this would be. If one of the shared neutral circuits were
> to
> trip due to a short-circuit or overload, the other circuit would remain
> hot.
> Anyone servicing any device in that junction box may be exposed to
> live conductors.
One cannot overemphasize that ANYONE who presumes that a circuit is
dead without checking it with a known-to-be-good voltage tester is
basically a moron and definitely NOT QUALIFIED to do electric work.
> Moving Forward There is a need for the two-pole device in retrofit and
> 240 V applications. As
> code requirements expand to these applications, Square D will offer a
> 120/240 V two-pole device. It will be specifically intended for 240 V
> and
> shared neutral applications, where shared neutrals exist and running
> new
> cable is not practical.
Sounds like a sales pitch.
> Before understanding all of the facts, one may believe that sharing
> neutrals
> is economical. The savings, if any, are not as large as one may think.
> In a
> typical residential application, two 75-foot-long (22.8 m) home runs
> could be
> wired with one cable, instead of two, by sharing neutrals. The typical
> cost of
> the three-conductor cable is about twice that of the two-conductor
> cable.
> Thus the money saved in cable cost is negligible.
Obviously this article was written long before the price of copper went
sky high.
> Compared to two
> one-pole
> AFCIs, the cost of a two-pole AFCI is only slightly higher.
> To reduce the difficulties found in pulling two cables for the homerun
> rather
> than one, several cable and wire manufacturers have introduced new
> fourconductor
> plus ground cables. These new cables offer independent neutrals,
> thus eliminating the potential problems associated with shared
> neutrals.
Talk about misinformation! The 12-2-2 w ground is intended strickly
for feeding bedroom circuits for AFCI's. Try pricing a two pole AFCI
breaker. This has nothing to do with the multi-wire, shared neutral
discussion.
> For more information about the disadvantages of shared neutrals, call
> Square D Cedar Rapids Application Support at (319) 369-6650.
> Electrical equipment should be installed, operated, serviced, and
> maintained only by
> qualified personnel.
Pretty much sums up the whole topic of shared neutrals. ELECTRIC WORK
SHOULD BE DONE BY QUALIFIED WORKERS. Qualified means, among other
things, That the person working on the electric equipment is WELL AWARE
OF THE HAZARDS INVOLVED.
>No responsibility is assumed by Schneider Electric
> for any
> consequences arising out of the use of this material.
Typical CYA.
John Grabowski
> I was using a voltage detector before. Using the pigtail and light,
> the GFI circuit breaker turns on the black and the dishwasher circuit
> breaker turns on the red. 240 volts across the red and black; 120
> volts across the red and neutral and the black and neutral. Thanks!
Glad to help. Thanks for posting back with the results.
mark
<tra...@optonline.net> wrote in message
news:1146081240.3...@i39g2000cwa.googlegroups.com...
So your saying that in my house {which is in pipe }I have a 3/4 in. pipe
from the panel to the other side of the house.At this point there is a box
and the different circuits then go out in 1/2 in. pipe to different
locations.In this home run box are 5 circuits (5 hots 3 neutrals)So I must
gang all 5 breakers together so if someone opens the box and takes all the
wire nuts off for some stupid reason they can not get hurt!!!!!!!NOT. Two,
even with the four conductor cable that still puts two hots in a box.In my
case to keep one circuit per box I would need to run approx. 25 pipes from
my panel to the different locations.,sorry no room for 25 pipes.
Doug Miller
>
>Doug Miller wrote:
>> In article <1145997918.6...@j33g2000cwa.googlegroups.com>,
> tra...@optonline.net wrote:
>> >
>> >Doug Miller wrote:
>> >> And I wouldn't be surprised if some of those homes had Edison circuits
> that
>> >> you weren't aware of. :-)
>> >
>> >Geez, you now think I'm so stupid I wouldn't recognize a double breaker
>> >in the panel? The only double breakers I have ever seen in my homes
>> >or other homes I've been involved with were for std 240V loads, ie
>> >dryer, stove, A/C. There were no other double breakers for shared
>> >neutral 120V circuits.
>>
>> NEC doesn't require double breakers unless both circuits supply a common
>> device. Using a double breaker is still prudent practice, but not all Edison
>> circuits will have them. Hence it's fairly easy to be unaware of having
> Edison
>> circuits unless you open up the panel and see the red wires.
>
>
>And this is exactly the type of thing that lead to the incidents in the
>DOE report I cited, where shared neutral circuits were not IDENTIFIED,
>leading to people being shocked.
>
type of circuit involved, but in the failure to identify it properly.
mark
Typical CYA.
Should we start about how you can run 3 hots with 1 neutral in a 3 phase
panel? ( with no high phase)
RayV
http://www.wistv.com/Global/story.asp?S=4818999&nav=menu36_3
tra...@optonline.net
> news:1146097499....@i40g2000cwc.googlegroups.com...
Now this is a classic. Here I give you a well written, concise
document about outlining the same problems and safety issues written by
Square D, and you attack it as a sales pitch to sell a circuit breaker
by Square D? Are you for real?
>
> > Before understanding all of the facts, one may believe that sharing
> > neutrals
> > is economical. The savings, if any, are not as large as one may think.
> > In a
> > typical residential application, two 75-foot-long (22.8 m) home runs
> > could be
> > wired with one cable, instead of two, by sharing neutrals. The typical
> > cost of
> > the three-conductor cable is about twice that of the two-conductor
> > cable.
> > Thus the money saved in cable cost is negligible.
>
>
> Obviously this article was written long before the price of copper went
> sky high.
>
>
Obviously you think $5 or $10 more for two 14/2 romex cables instead of
one 14/3 is a lot of money to eliminate the problems and safety issues
that I showed you were documented by the DOE and Square D. Most
reasonable people would say that's a small price to pay. Except Doug,
who will say it's still 25% LOL
> > Compared to two
> > one-pole
> > AFCIs, the cost of a two-pole AFCI is only slightly higher.
> > To reduce the difficulties found in pulling two cables for the homerun
> > rather
> > than one, several cable and wire manufacturers have introduced new
> > fourconductor
> > plus ground cables. These new cables offer independent neutrals,
> > thus eliminating the potential problems associated with shared
> > neutrals.
>
> Talk about misinformation! The 12-2-2 w ground is intended strickly
> for feeding bedroom circuits for AFCI's. Try pricing a two pole AFCI
> breaker. This has nothing to do with the multi-wire, shared neutral
> discussion.
>
>
Not misinformation at all. Are you saying that the new cables don't
reduce the difficulty in pulling two cables? Or that they don't offer
a way to eliminate shared neutrals? Or that they can ONLY be used for
AFCIs?
> > For more information about the disadvantages of shared neutrals, call
> > Square D Cedar Rapids Application Support at (319) 369-6650.
> > Electrical equipment should be installed, operated, serviced, and
> > maintained only by
> > qualified personnel.
>
> Pretty much sums up the whole topic of shared neutrals. ELECTRIC WORK
> SHOULD BE DONE BY QUALIFIED WORKERS. Qualified means, among other
> things, That the person working on the electric equipment is WELL AWARE
> OF THE HAZARDS INVOLVED.
>
>
If you were as concerned about the hazards as you claim, then you'd
acknowledge the legitimate points made by Square D, and the DOE, both
of which have no axe to grind instead of dismissing them. In
reality, all you want to do is save a few bucks on a job, or do it as
easy as possible, even if there are better ways to do it that cost just
a little more.
By the way, I've given you excellent references right on the point from
both these sources. Perhaps you could provide us some similar credible
references or links discussing why shared neutrals are a great thing to
have installed in a home?
> >No responsibility is assumed by Schneider Electric
> > for any
> > consequences arising out of the use of this material.
>
> Typical CYA.
And even this you have to make disparaging remarks about? A legal
disclaimer in this type of thing is expected by those of us who read
and learn from similar tech bulletins.
Doug Miller
>I don't know if this guy was an electrician, but look what can happen.
>
>http://www.wistv.com/Global/story.asp?S=4818999&nav=menu36_3
>
Chris Lewis
> It's not common in the sense that I've lived in many homes for many
> years and I have never seen one.
On the other hand, every home built here in the past 50 years[+]
has at least two of these circuits. Feeding kitchen counter outlets.
They used to be quite common (and are still NEC-legal I believe as a substitute
for 20A circuits - or was until GFCI requirements became common) as
kitchen counter outlets in the US as well.
> And if you asked the average
> homeowner what an edison circuit or shared neutral is, virtually no one
> would have a clue. Yet, it's common for homeowners to replace a wall
> outlet or switch.
Despite a lot of them having no idea how a three or four way lighting
circuit, or a outlet split between switched and unswitched works or
should be wired. Should we ban those too?
You could turn off the switch, and the other side of the outlet zaps you.
Ooh! ;-)
Or four wire stoves and dryers.
> If someone comes in this newgroup and asks how to do
> that, I've never seen anyone suggest to be careful, it may be an edison
> circuit or to verify that it's not being fed by dual breakers, perhaps
> not linked or correctly identified.
> And the point is why do this? All that is being saved is one lousy,
> cheap neutral wire.
And a ground wire.
It's more than that. It can save significant labor in certain situations.
> I can see doing this if there is no easy way to do
> it otherwise, eg old work, but I would never do it for new work.
I do it moderately frequently in new work - long runs to where I
need two circuits. Saves a lot of time and at least halves the
possibility of damaging a cable.
They're particularly useful as workshop outlets. One dual receptacle, one
box, one cable, 30A of 120V available for two simultaneous devices (like
the radiant heater and the drill press ;-).
> As to the dangers of this practice, here, from the DOE:
> http://www.eh.doe.gov/paa/oesummary/oesummary2005/oes2005-15-01.pdf
> They discuss that shared neutrals circuits pose unique dangers if not
> properly identifed and cite incidents that actually occurred. And
> this is for industrial settings, where you can expect skilled workers,
> not the average home, where Joe homeowner may be changing a switch.
> Now you could say, but that's because they were not properly
> identified. But why not just avoid it where possible all together?
Both improperly identified, and improperly breakered in situations where
code is expecting more of the people working on the wiring yet, the code
isn't as strict in some ways (leading to much more complicated wiring).
And similar to hazards that people can encounter _without_ sharing neutrals.
Eg: switched neutrals. Cross-connected neutrals with K&T. Using bare wires
as neutrals. Main panel neutrals springing loose. Etc.
NEC (and CEC) have sections on multi-wire branches that alleviate most
of these issues. Eg: pigtailing neutrals, tiebarred breakers etc.
I know that this may seem a trifle elitist (or the opposite in fact ;-),
but any homeowner working on wiring has to recognize their own limitations,
and be ultra cautious about what they encounter. Make no assumptions, test
every wire, and if they don't understand why a red conductor appears
in a box that doesn't also have a three-way switch or fixture controlled
by one, they'd better be very very careful. Better, read up on them, or
get help.
[+] Except for the last couple where 20A US-style counter outlets are
also becoming code in order to facilitate cheaper GFCI protection. You can
still use split duals, but you have to use dual GFCI breakers for them now.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
Chris Lewis
> Do you mean by this that the top of the outlet would be powered by the
> red and the bottom of the outlet would be powered by the black.
Precisely.
> If
> not, I don't understand why you would need to remove the tab.
That's one of the reasons why the tab is removable ;-)
Chris Lewis
> NEC doesn't require double breakers unless both circuits supply a common
> device. Using a double breaker is still prudent practice, but not all Edison
> circuits will have them. Hence it's fairly easy to be unaware of having Edison
> circuits unless you open up the panel and see the red wires.
Canadian code is stricter. Every hot in a box must be killable by
one disconnect. There are some exceptions, but they're primarily
industrial situations with only licensed electricians permitted
to touch it, and requires labeling and locks etc.
This extends to the point (actually stricter than this per-se) where
CEC compliant main panels _MUST_ separate the main breaker enclosure
from the branch breaker enclosure by a metal plate of thus and so
guage. When you remove the metal cover for the branch breaker enclosure,
it's not permitted that it also expose the feed conductors or main breaker
terminals.
Eg: Canadian panels have two hatches.
Chris Lewis
> I don't know if this guy was an electrician, but look what can happen.
> http://www.wistv.com/Global/story.asp?S=4818999&nav=menu36_3
Heh,
I heard of an incident where two people were killed while trying to steal
telephone trunk cable (big multi pair cable) off a pair of poles.
You wouldn't think telephone circuits would do that would you?
Well, it turned out that there was a relatively low amperage but high
voltage ground fault in power distribution that cross-connected
to one end of this cable. Through a bad ground or a frayed wire
on a pole perhaps.
Low meaning not enough to blow a fuse while the trunk cable ground
sheath was grounding it. But high enough (with probably at least
4Kv behind it) to fry them both when they severed the ground sheath
and touched the wrong end.
Chris Lewis
> tra...@optonline.net wrote:
> > Moving Forward There is a need for the two-pole device in retrofit and
> > 240 V applications. As
> > code requirements expand to these applications, Square D will offer a
> > 120/240 V two-pole device. It will be specifically intended for 240 V
> > and
> > shared neutral applications, where shared neutrals exist and running
> > new
> > cable is not practical.
> Sounds like a sales pitch.
More than that, they appear to be offering something _new_ that they
already don't. Huh? Square D doesn't make dual breakers already?
Something is wrong here.
> > Compared to two
> > one-pole
> > AFCIs, the cost of a two-pole AFCI is only slightly higher.
Ah, _AFCIs_. That's different.
They need two-pole AFCIs _anyway_ if they plan on having them
for anything that needs 240V.
RayV
bottom switched or versa visa. Before this thread If I would have seen
an outlet with a red on top a black on the bottom and one white I would
have expected one of them to be switched. Now I know that further
checking is warranted.
RayV
broken and one white. It also doesn't seem like either is switched.
Is there a way to test if the black is on one leg and the red on
another an then assume it is an edison circuit?
It could also be that someone previously eliminated a switch for the
top of the outlet and spackled over the box.
I know that a properly wired edison circuit would have pigtailed
nuetrals (since this thread) but my MIL's house has several of these
circuits running to the third floor and none of the nuetrals are
pigtailed. So not too long ago I was exposed to one of these circuits
and didn't even know it.
Doug Miller
>OK suppose I come across an outlet with a red and a black with the tab
>broken and one white. It also doesn't seem like either is switched.
>Is there a way to test if the black is on one leg and the red on
>another an then assume it is an edison circuit?
With a voltmeter.
You should see 120V from red to white, and 120V from black to white,
regardless of the type of circuit. If you don't, then either the red or black
is in fact switched, or you have a problem somewhere.
If you see 240V between red and black, then it's an Edison circuit, properly
wired -- if you see 0V instead, you have an IMproperly wired Edison circuit,
with both the red and the black on the same leg of the service. This is a
dangerous condition that must be corrected.
Bud--
> In article <1146187013.4...@g10g2000cwb.googlegroups.com>, "RayV" <Nunya...@comcast.net> wrote:
>
>> It also doesn't seem like either is switched.
> if you see 0V instead, you have an IMproperly wired Edison circuit,
> with both the red and the black on the same leg of the service. This is a
> dangerous condition that must be corrected.
>
As an addition - it also still could be switched or have been switched
in the past. Kill one circuit and make sure the other wire is also
killed. If the 2nd wire stays live it is an improper Edison.
Verify all wires, including white, are dead when working on them. It
might be a good idea to retest wires that are joined at a wire nut or
device if they are disconnected. A white wire in the earlier DOE link
became live - all but one case from non-code wiring.
bud--
Stan
>
> Ah, _AFCIs_. That's different.
>
> They need two-pole AFCIs _anyway_ if they plan on having them
> for anything that needs 240V.
> --
Something similar to GFCIs? But manufactured as part of the circuit breaker?
Is that what the UK calls RCDs?
Goedjn
wrote:
Arc Fault Circut interrupter.
Ground faults kill people, Arc faults start fires.
Chris Lewis
> >OK suppose I come across an outlet with a red and a black with the tab
> >broken and one white. It also doesn't seem like either is switched.
> >Is there a way to test if the black is on one leg and the red on
> >another an then assume it is an edison circuit?
> With a voltmeter.
> You should see 120V from red to white, and 120V from black to white,
> regardless of the type of circuit. If you don't, then either the red or black
> is in fact switched, or you have a problem somewhere.
> If you see 240V between red and black, then it's an Edison circuit, properly
> wired -- if you see 0V instead, you have an IMproperly wired Edison circuit,
> with both the red and the black on the same leg of the service. This is a
> dangerous condition that must be corrected.
If you see 0V, it could be a half-switched outlet with the switch _on_ - you can't
tell the difference between that and an improperly wired Edison circuit this way.
If you're comfortable pulling the cover off the breakers in the panel, hunt
for cables with black and red going into the panel.