Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable that
has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. Other than that,
#12 would be fine with me.

Next, is there a rule of thumb for how many hot wires can share one neutral
of the same gauge? If using different gauges, is there a "gauge ratio", ie,
some formula for cross sectional area between total hots and total neutrals?

tia.
--
EA

Existential Angst wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable that
has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. Other than that,
#12 would be fine with me.

There's nothing "unmodern" about 14 for 15A circuits.

I'd recommend sticking w/ same gauge as the original circuit for the
reason mentioned.

Remember to not bury connections in inaccessible places.

Next, is there a rule of thumb for how many hot wires can share one neutral
of the same gauge? If using different gauges, is there a "gauge ratio", ie,
some formula for cross sectional area between total hots and total neutrals?


Don't follow this question. Each hot needs its own return neutral.
If you're talking about 3-wire ("Edison") circuits, if properly wired
the return is in effect a neutral w/ a balancing currents from the two
sides if both are loaded equally; hence only the same size conductor is
required for a single-sided load.

If that isn't it, I have no clue what you're thinking.

--

"dpb" wrote in message ...
Existential Angst wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable
that has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and
to not take liberties with 20 or 30 amp fuses or breakers. Other than
that, #12 would be fine with me.

There's nothing "unmodern" about 14 for 15A circuits.

Really? Does the NEC state that?

I thought #12 was the de-facto "standard" for wiring, but mebbe that was
just NYC in its oppressive heyday, before it relented and went with the NEC.
In that heyday in NYC, 20 A breakers were illegal on #12 wire! Altho
after inspection, few people adhered to that limit.

What is the max breaker allowable on #14 and #12 wire with modern
insulation, nowadays?
Ditto, with cloth insulation?



I'd recommend sticking w/ same gauge as the original circuit for the
reason mentioned.

Remember to not bury connections in inaccessible places.

Indeed!


Next, is there a rule of thumb for how many hot wires can share one
neutral of the same gauge? If using different gauges, is there a "gauge
ratio", ie, some formula for cross sectional area between total hots and
total neutrals?


Don't follow this question. Each hot needs its own return neutral.
If you're talking about 3-wire ("Edison") circuits, if properly wired the
return is in effect a neutral w/ a balancing currents from the two sides
if both are loaded equally; hence only the same size conductor is required
for a single-sided load.

If that isn't it, I have no clue what you're thinking.

I think you answered the Q: If each hot in a 3-wire bx is connected to a
different leg in the panel, then they can share a common equal-sized
neutral. So the "ratio" would be 2:1.

Which is why the neutral in main service can be "de-rated" rel. to the hots,
because the assumption is that there will in fact be some balancing of the
load between the two legs in "Net usage", reducing the demand on the
neutral.
In a worst case scenario -- full load occurring on only one leg -- then the
neutral proly should be equal in gauge to the hot gauge. But statistically,
esp. in large buildings, this is unlikely.
iirc, the svc neutral to large buildings can be smaller than the gauge of
either hot leg, but I wouldn't bet the farm on my memory.
--
EA

--

On Nov 6, 12:20*pm, dpb wrote:
Existential Angst wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable that
has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. *Other than that,
#12 would be fine with me.

There's nothing "unmodern" about 14 for 15A circuits.

I'd recommend sticking w/ same gauge as the original circuit for the
reason mentioned.

Remember to not bury connections in inaccessible places.

Next, *is there a rule of thumb for how many hot wires can share one neutral
of the same gauge? *If using different gauges, is there a "gauge ratio", ie,
some formula for cross sectional area between total hots and total neutrals?

Don't follow this question. *Each hot needs its own return neutral.
If you're talking about 3-wire ("Edison") circuits, if properly wired
the return is in effect a neutral w/ a balancing currents from the two
sides if both are loaded equally; hence only the same size conductor is
required for a single-sided load.

If that isn't it, I have no clue what you're thinking.

--

If I'm following what he's asking correctly, I think he's trying to
pigtail some existing wires within a breaker panel to extend them to
their connection points. I also am guessing that this involves more
than one circuit, so he wants to connect several neutrals to a single
larger wire with a wire nut (or crimp cap, solder, whatever) and then
connect that larger wire to the bus, rather than pigtail each
individual neutral and connect them individually to the bus.

However, I have no input on whether this is even a valid
configuration; unless I were out of space on the bus bar I think I
would probably just pigtail each wire individually with a wire of the
same gauge - BUT I have no idea if what he's suggesting is OK per
code. (I suspect not; you wouldn't want a single point of failure to
affect multiple circuits. But that's just a guess based on thinking
it through, not actual knowledge of code.)

nate

In article , "Existential Angst" wrote:
"dpb" wrote in message ...
Existential Angst wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable
that has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and
to not take liberties with 20 or 30 amp fuses or breakers. Other than
that, #12 would be fine with me.

There's nothing "unmodern" about 14 for 15A circuits.

Really? Does the NEC state that?

Yes. Has for decades.

I thought #12 was the de-facto "standard" for wiring, but mebbe that was
just NYC in its oppressive heyday, before it relented and went with the NEC.
In that heyday in NYC, 20 A breakers were illegal on #12 wire! Altho
after inspection, few people adhered to that limit.

What is the max breaker allowable on #14 and #12 wire with modern
insulation, nowadays?
Ditto, with cloth insulation?

15A and 20A, respectively, regardless of the type of insulation.

"Existential Angst" wrote in message
...
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable
that has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. Other than that,
#12 would be fine with me.

Next, is there a rule of thumb for how many hot wires can share one
neutral of the same gauge? If using different gauges, is there a "gauge
ratio", ie, some formula for cross sectional area between total hots and
total neutrals?

tia.
--
EA
keep the conductors the same size as is existing

14ga is and has always been fine for 15 amp circuits

12ga is and has always been fine for 20 amp circuits (even in NYC)

NYC, prior to 2005 has always used the NEC as the basis for electric code.
Only certain areas did they require more stringent rules.

Your neutral can be shared by as many hot legs as your service has,
typically 2

"RBM" wrote in message
...

"Existential Angst" wrote in message
...
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable
that has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and
to not take liberties with 20 or 30 amp fuses or breakers. Other than
that, #12 would be fine with me.

Next, is there a rule of thumb for how many hot wires can share one
neutral of the same gauge? If using different gauges, is there a "gauge
ratio", ie, some formula for cross sectional area between total hots and
total neutrals?

tia.
--
EA
keep the conductors the same size as is existing

14ga is and has always been fine for 15 amp circuits

12ga is and has always been fine for 20 amp circuits (even in NYC)

NYC, prior to 2005 has always used the NEC as the basis for electric code.
Only certain areas did they require more stringent rules.

Well, iiuc, ALL municipalities use the NEC as a "basis".

Regarding NYC, I read the opposite here on this ng in a recent thread:
NYC relaxed its onerous electric code to substantially the NEC AFTER 2001
or 2003. Before that, it was quite stringent.

I know for a fact (well, at least if my bosses were correct!) that in the
1980's, you could *not* put 20A breakers on #12 wire -- at least not before
inspection.

As another example, in those days, you were allowed eight #12 conductors in
1" EMT -- in fact, it was 3, 5, and 8 for 1/2, 3/4, and 1" EMT,
respectively.

Nowadays, for 1" emt, NYC allows pretty much what the NEC allows -- pert
near close to 20 wires in 1" emt! What a diff.

This may also reflect more modern wire insulation material.
--
EA


Your neutral can be shared by as many hot legs as your service has,
typically 2

"Existential Angst" wrote in message
...
"RBM" wrote in message
...

"Existential Angst" wrote in message
...
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable
that has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and
future people that Hey, this old wire is a little lighter than modern
#12, and to not take liberties with 20 or 30 amp fuses or breakers.
Other than that, #12 would be fine with me.

Next, is there a rule of thumb for how many hot wires can share one
neutral of the same gauge? If using different gauges, is there a "gauge
ratio", ie, some formula for cross sectional area between total hots and
total neutrals?

tia.
--
EA
keep the conductors the same size as is existing

14ga is and has always been fine for 15 amp circuits

12ga is and has always been fine for 20 amp circuits (even in NYC)

NYC, prior to 2005 has always used the NEC as the basis for electric
code. Only certain areas did they require more stringent rules.

Well, iiuc, ALL municipalities use the NEC as a "basis".

Regarding NYC, I read the opposite here on this ng in a recent thread:
NYC relaxed its onerous electric code to substantially the NEC AFTER 2001
or 2003. Before that, it was quite stringent.

I know for a fact (well, at least if my bosses were correct!) that in the
1980's, you could *not* put 20A breakers on #12 wire -- at least not
before inspection.

As another example, in those days, you were allowed eight #12 conductors
in 1" EMT -- in fact, it was 3, 5, and 8 for 1/2, 3/4, and 1" EMT,
respectively.

Nowadays, for 1" emt, NYC allows pretty much what the NEC allows -- pert
near close to 20 wires in 1" emt! What a diff.

This may also reflect more modern wire insulation material.
--
EA


Your neutral can be shared by as many hot legs as your service has,
typically 2


Every three years a new set of rules comes out in the NEC. It's entirely
possible that the "conductors in conduit" changes are reflective of that.
I've never seen #10 used for 20 amp circuits in NYC. If the conductors were
aluminum, not copper, that would be the case, although I'm not sure if NYC
ever allowed small conductor aluminum wire.

On Nov 6, 11:37*am, "Existential Angst"
wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable that
has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

If there's even an inch of #14, old or new, anywhere in the circuit,
then that circuit needs to be protected with a 15A breaker or fuse,
and there is essentially zero advantage to splicing in any #12, unless
it's all you have and the stores are closed. Possible exception is if
it's a very very long run, like to an outbuilding, in which case you
maybe need to use #12 or heavier with 15A protection.

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. *Other than that,
#12 would be fine with me.

If it's #12 that's visible leaving the panel, then there's a danger
that someone will assume the whole circuit is #12 and thus they might
put in a 20A fuse. So if your new wire is going to go into the panel,
then there's a very good reason to make it the same was what's already
in the rest of the circuit.

(Besides, some will tell you that old wire is HEAVIER than new stuff
of the same nominal gauge. No matter. Old #12 or new #12 should ok
with 20A, unless it's damaged, in which case it shouldn't be used at
all.)

Next, *is there a rule of thumb for how many hot wires can share one neutral
of the same gauge? *If using different gauges, is there a "gauge ratio", ie,
some formula for cross sectional area between total hots and total neutrals?

You got to tell us what the heck is going on here.

Chip C

Existential Angst wrote:
....
The Q might be then, What constitutes "corresponding neutrals": one
neutral for one or two hots, or one big neutral for a bunch of hots?

Same as I gave you before except for 3-wire circuits--_every_ hot must
have its corresponding neutral, no exceptions.

--

On 11/6/2009 8:38 PM dpb spake thus:

Existential Angst wrote:
...
The Q might be then, What constitutes "corresponding neutrals": one
neutral for one or two hots, or one big neutral for a bunch of hots?

Same as I gave you before except for 3-wire circuits--_every_ hot must
have its corresponding neutral, no exceptions.

Yes, and from the OP's continued queries, it sounds more and more like
they don't really don't know much about wiring, which makes what they're
trying to do pretty doubtful.

To reiterate: the *only* circumstance where two hot wires can share a
neutral is in a so-called "Edison" circuit. The requirement is that the
hot wires must be on different phases--in other words, from different
buses in the distribution panel. That way, the sum of currents in the
one neutral can never exceed the wire's rating. The OP said some vague
things about "balancing loads": it's a whole lot more specific than that.


--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

"David Nebenzahl" wrote in message
.com...
On 11/6/2009 8:38 PM dpb spake thus:

Existential Angst wrote:
...
The Q might be then, What constitutes "corresponding neutrals": one
neutral for one or two hots, or one big neutral for a bunch of hots?

Same as I gave you before except for 3-wire circuits--_every_ hot must
have its corresponding neutral, no exceptions.

Yes, and from the OP's continued queries, it sounds more and more like
they don't really don't know much about wiring, which makes what they're
trying to do pretty doubtful.

To reiterate: the *only* circumstance where two hot wires can share a
neutral is in a so-called "Edison" circuit. The requirement is that the
hot wires must be on different phases--in other words, from different
buses in the distribution panel. That way, the sum of currents in the one
neutral can never exceed the wire's rating. The OP said some vague things
about "balancing loads": it's a whole lot more specific than that.

There is nothing vague about "balancing loads".
What you may find vague, or perhaps are just unclear on yourself, is along
what part of the run can the load be balanced.

If you have 20 2-wire bx cables stopping, say, 10 feet short of a 20 circuit
panel, then, it seems to me, you can de facto *make* 10 edison circuits up
to the splice points, and therefore need only 10 neutrals going between the
panel and those 20 cables.

Thus, the edison circuit business is dependent on the actual *geometry of
the wiring*, ie, "partial length" edison circuits are possible.

Thus, your seemingly restrictive "only circumstance" for two hot wires
sharing one neutral is in fact a fairly non-limiting requirement in this
splicing circumstance, as ultimately, if a 20 circuit 240 V panel is filled,
you will *always* be able to make 10 edison circuits, for at least part of
the run.

AND, if you grok the above, then it follows that for that length of the
"edison run", you could, in principle, use one big neutral.

Not saying I will do this, just trying to eliminate some, well, vagaries.

Love your sig.
--
EA








--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

On 11/6/2009 11:08 PM Existential Angst spake thus:

If you have 20 2-wire bx cables stopping, say, 10 feet short of a 20 circuit
panel, then, it seems to me, you can de facto *make* 10 edison circuits up
to the splice points, and therefore need only 10 neutrals going between the
panel and those 20 cables.

Thus, the edison circuit business is dependent on the actual *geometry of
the wiring*, ie, "partial length" edison circuits are possible.

Thus, your seemingly restrictive "only circumstance" for two hot wires
sharing one neutral is in fact a fairly non-limiting requirement in this
splicing circumstance, as ultimately, if a 20 circuit 240 V panel is filled,
you will *always* be able to make 10 edison circuits, for at least part of
the run.

So you do understand the concept of "Edison" circuits, right? That you
can't just grab any two hots, run a neutral with them and call it a day?
Please tell us you understand this, or don't try it.

Do you know *why* you can use just one neutral to serve two hots with
this kind of circuit?


--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

"David Nebenzahl" wrote in message
.com...
On 11/6/2009 11:08 PM Existential Angst spake thus:

If you have 20 2-wire bx cables stopping, say, 10 feet short of a 20
circuit panel, then, it seems to me, you can de facto *make* 10 edison
circuits up to the splice points, and therefore need only 10 neutrals
going between the panel and those 20 cables.

Thus, the edison circuit business is dependent on the actual *geometry of
the wiring*, ie, "partial length" edison circuits are possible.

Thus, your seemingly restrictive "only circumstance" for two hot wires
sharing one neutral is in fact a fairly non-limiting requirement in this
splicing circumstance, as ultimately, if a 20 circuit 240 V panel is
filled, you will *always* be able to make 10 edison circuits, for at
least part of the run.

So you do understand the concept of "Edison" circuits, right? That you
can't just grab any two hots, run a neutral with them and call it a day?
Please tell us you understand this, or don't try it.

My first reply to dpk would indicate that I do understand edison circuits.
Your previous post, and this one, indicate that you have a problem
understanding that I understand.


Do you know *why* you can use just one neutral to serve two hots with this
kind of circuit?

If I didn't, would you tell me?

Here's the deal:

If the loads on each service leg are "balanced" (recall that vague
reference?), ie, electrically identical ito impedance, you wouldn't need a
neutral at all. The total voltage applied to the two loads (effectively in
series here) is 240 V, and the voltage drop across each load on a leg is
then 240/2 = 120 V, which is the appliance rating.

But what if one load is a 100 W bulb is on one leg, and a 1,000 W toaster is
on another, and the neutral is lifted.
The voltage drop across the bulb is 10/11 * 240 and that across the toaster
is 1/11 * 240. Thus, the bulb will burn out, but not the toaster.

Thus, the neutral acts as a kind of centertap for unbalanced loads on each
leg, proly best analyzed with Thevenin's theorem -- in wiki, if anyone is
innerested, altho the sample problems there are not very illuminating.
Thevenin's theorem is essentially Ohm's Law on effing steroids.... wow.....

This Edison business explains why, in the presence of a a marginal or
inadequate neutral, adding or switching on another load will actually make
lights *brighten*, because now current from one side of the svc is not being
driven through a high-resistance neutral, and instead flows better through
the now-balanced load on the other svc leg.

This neutral business clearly explains why 240 V appliances are inherently
superior from an electrical loading pov -- both legs are balanced by
definition, and no neutral is required at all.
Plus, at 240 V, there is much less IR drop, and much less I^2R transmission
loss. It's better all the way around.

Europe operates on 220-240 V, but according to one poster here, that is
between one leg and neutral, so they have the same "balancing problem" we
do, just at a higher voltage. The key is to have 240 V *between two hot
legs* -- and, of course, corresponding 240 V appliances.

Having said all this, I'll proly not go Edison-crazy, and just splice all
neutrals directly to the new panel. This way, there is no possibility of
future incompatibilities resulting from unwitting changes.

--
EA







--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

On Nov 6, 12:53*pm, "Existential Angst"
wrote:
"dpb" wrote in ...
Existential Angst wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable
that has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and
to not take liberties with 20 or 30 amp fuses or breakers. *Other than
that, #12 would be fine with me.

There's nothing "unmodern" about 14 for 15A circuits.

Really? *Does the NEC state that?

I thought #12 was the de-facto "standard" for wiring, but mebbe that was
just NYC in its oppressive heyday, before it relented and went with the NEC.
In that heyday in NYC, * 20 A breakers were illegal on #12 wire! *Altho
after inspection, few people adhered to that limit.

What is the max breaker allowable on #14 and #12 wire with modern
insulation, nowadays?
Ditto, with cloth insulation?



I'd recommend sticking w/ same gauge as the original circuit for the
reason mentioned.

Remember to not bury connections in inaccessible places.

Indeed!



Next, *is there a rule of thumb for how many hot wires can share one
neutral of the same gauge? *If using different gauges, is there a "gauge
ratio", ie, some formula for cross sectional area between total hots and
total neutrals?

Don't follow this question. *Each hot needs its own return neutral.
If you're talking about 3-wire ("Edison") circuits, if properly wired the
return is in effect a neutral w/ a balancing currents from the two sides
if both are loaded equally; hence only the same size conductor is required
for a single-sided load.

If that isn't it, I have no clue what you're thinking.

I think you answered the Q: *If each hot *in a 3-wire bx *is connected to a
different leg in the panel, then they can share a common equal-sized
neutral. *So the "ratio" would be 2:1.

Which is why the neutral in main service can be "de-rated" rel. to the hots,
because the assumption is that there will in fact be some balancing of the
load between the two legs in "Net usage", reducing the demand on the
neutral.


The neutral is not derated in the service. Let's take a 200 amps
service. ALL the conductors in the service cable are rated for 200
amp capacity because that is the max current you can have flowing in
them. If it's a pure 240volt load of 48KVA or a balanced 120volt
load of 48KVA, then 200 amps is flowing in the two hots, zero in the
neutral. If it's a 120volt unbalanced load, then 200 amps is flowing
between one hot and the neutral.

Gee, seems I recall having this discussion here before.....




In a worst case scenario -- full load occurring on only one leg -- then the
neutral proly should be equal in gauge to the hot gauge. But statistically,
esp. in large buildings, this is unlikely.
*iirc, the svc neutral to large buildings can be smaller than the gauge of
either hot leg, but I wouldn't bet the farm on my memory.
--
EA





--- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

On Nov 6, 5:39*pm, Chip C wrote:
On Nov 6, 11:37*am, "Existential Angst"
wrote:

Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable that
has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

If there's even an inch of #14, old or new, anywhere in the circuit,
then that circuit needs to be protected with a 15A breaker or fuse,
and there is essentially zero advantage to splicing in any #12, unless
it's all you have and the stores are closed. Possible exception is if
it's a very very long run, like to an outbuilding, in which case you
maybe need to use #12 or heavier with 15A protection.

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. *Other than that,
#12 would be fine with me.

If it's #12 that's visible leaving the panel, then there's a danger
that someone will assume the whole circuit is #12 and thus they might
put in a 20A fuse. So if your new wire is going to go into the panel,
then there's a very good reason to make it the same was what's already
in the rest of the circuit.

(Besides, some will tell you that old wire is HEAVIER than new stuff
of the same nominal gauge. No matter. Old #12 or new #12 should ok
with 20A, unless it's damaged, in which case it shouldn't be used at
all.)

Next, *is there a rule of thumb for how many hot wires can share one neutral
of the same gauge? *If using different gauges, is there a "gauge ratio", ie,
some formula for cross sectional area between total hots and total neutrals?

You got to tell us what the heck is going on here.

Chip C

I don't know either, but it doesn't sound like whatever is going on is
good.

In article , "Existential Angst" wrote:
"David Nebenzahl" wrote in message
s.com...

Do you know *why* you can use just one neutral to serve two hots with this
kind of circuit?

If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole breaker,
you're going to have a tough time meeting Code with that monster circuit you
proposed.

The reason Code requires this is straightforward: the neutral wire carries
current. If one hot leg of a multiwire circuit is left powered on, and any
load on that leg is in use, the current drawn by that load is flowing in the
neutral -- presenting a risk of fatal electric shock to anyone servicing the
other leg of that circuit.

"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"David Nebenzahl" wrote in message
rs.com...

Do you know *why* you can use just one neutral to serve two hots with
this
kind of circuit?

If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that
all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole breaker,
you're going to have a tough time meeting Code with that monster circuit
you
proposed.

The reason Code requires this is straightforward: the neutral wire carries
current. If one hot leg of a multiwire circuit is left powered on, and any
load on that leg is in use, the current drawn by that load is flowing in
the
neutral -- presenting a risk of fatal electric shock to anyone servicing
the
other leg of that circuit.

So are you saying that in a simple 3 wire bx cable, with the two hots
sharing a neutral, you'd need a two-pole breaker?
--
EA

Existential Angst wrote:
"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"David Nebenzahl" wrote in message
.com...
Do you know *why* you can use just one neutral to serve two hots with
this
kind of circuit?
If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that
all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole breaker,
you're going to have a tough time meeting Code with that monster circuit
you
proposed.

The reason Code requires this is straightforward: the neutral wire carries
current. If one hot leg of a multiwire circuit is left powered on, and any
load on that leg is in use, the current drawn by that load is flowing in
the
neutral -- presenting a risk of fatal electric shock to anyone servicing
the
other leg of that circuit.

So are you saying that in a simple 3 wire bx cable, with the two hots
sharing a neutral, you'd need a two-pole breaker?

yup, exactly. Or if they were two single pole breakers they'd have to
be next to each other with a handle tie.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Existential Angst wrote:

"David Nebenzahl" wrote in message
.com...
On 11/6/2009 11:08 PM Existential Angst spake thus:

If you have 20 2-wire bx cables stopping, say, 10 feet short of a 20
circuit panel, then, it seems to me, you can de facto *make* 10 edison
circuits up to the splice points, and therefore need only 10 neutrals
going between the panel and those 20 cables.

Thus, the edison circuit business is dependent on the actual *geometry of
the wiring*, ie, "partial length" edison circuits are possible.

Thus, your seemingly restrictive "only circumstance" for two hot wires
sharing one neutral is in fact a fairly non-limiting requirement in this
splicing circumstance, as ultimately, if a 20 circuit 240 V panel is
filled, you will *always* be able to make 10 edison circuits, for at
least part of the run.

So you do understand the concept of "Edison" circuits, right? That you
can't just grab any two hots, run a neutral with them and call it a day?
Please tell us you understand this, or don't try it.

My first reply to dpk would indicate that I do understand edison circuits.
Your previous post, and this one, indicate that you have a problem
understanding that I understand.


Do you know *why* you can use just one neutral to serve two hots with this
kind of circuit?

If I didn't, would you tell me?

Here's the deal:

If the loads on each service leg are "balanced" (recall that vague
reference?), ie, electrically identical ito impedance, you wouldn't need a
neutral at all. The total voltage applied to the two loads (effectively in
series here) is 240 V, and the voltage drop across each load on a leg is
then 240/2 = 120 V, which is the appliance rating.

But what if one load is a 100 W bulb is on one leg, and a 1,000 W toaster is
on another, and the neutral is lifted.
The voltage drop across the bulb is 10/11 * 240 and that across the toaster
is 1/11 * 240. Thus, the bulb will burn out, but not the toaster.

Thus, the neutral acts as a kind of centertap for unbalanced loads on each
leg, proly best analyzed with Thevenin's theorem -- in wiki, if anyone is
innerested, altho the sample problems there are not very illuminating.
Thevenin's theorem is essentially Ohm's Law on effing steroids.... wow.....

This Edison business explains why, in the presence of a a marginal or
inadequate neutral, adding or switching on another load will actually make
lights *brighten*, because now current from one side of the svc is not being
driven through a high-resistance neutral, and instead flows better through
the now-balanced load on the other svc leg.

This neutral business clearly explains why 240 V appliances are inherently
superior from an electrical loading pov -- both legs are balanced by
definition, and no neutral is required at all.
Plus, at 240 V, there is much less IR drop, and much less I^2R transmission
loss. It's better all the way around.

Europe operates on 220-240 V, but according to one poster here, that is
between one leg and neutral, so they have the same "balancing problem" we
do, just at a higher voltage. The key is to have 240 V *between two hot
legs* -- and, of course, corresponding 240 V appliances.

Having said all this, I'll proly not go Edison-crazy, and just splice all
neutrals directly to the new panel. This way, there is no possibility of
future incompatibilities resulting from unwitting changes.

--
EA



--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

Perhaps just put a suitable pull box where the lines will reach, and
install a ground buss bar kit and an isolated neutral bus bar kit, and
tie them to the ground and neutral in the panel with appropriately sized
conductors. Since it's a short run, the same gauge as the panel neutral
and ground connections would certainly be sufficient.

When I have done this type of extension for a panel replacement, I have
normally done something like this for the grounds, but not the neutral.

"Nate Nagel" wrote in message
...
Existential Angst wrote:
"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"David Nebenzahl" wrote in message
.com...
Do you know *why* you can use just one neutral to serve two hots with
this
kind of circuit?
If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that
all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole
breaker,
you're going to have a tough time meeting Code with that monster circuit
you
proposed.

The reason Code requires this is straightforward: the neutral wire
carries
current. If one hot leg of a multiwire circuit is left powered on, and
any
load on that leg is in use, the current drawn by that load is flowing in
the
neutral -- presenting a risk of fatal electric shock to anyone servicing
the
other leg of that circuit.

So are you saying that in a simple 3 wire bx cable, with the two hots
sharing a neutral, you'd need a two-pole breaker?

yup, exactly. Or if they were two single pole breakers they'd have to be
next to each other with a handle tie.

OK, one more clarification:
Said 3-wire bx cable, with two hots, one neutral, each hot on a sep. svc
leg, and each hot powering a 120V appliance, right?
Say, one hot for the microwave, and the other hot for the toaster, with
each neutral from that appliance's outlet/box being pigtailed together to
one neutral going back to the breaker panel. Good so far?

You would then put those two hots on a double pole breaker? So that if the
toaster goes out, the microwave goes out as well? Hmmmmm......
--
EA





nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

In article , "Existential Angst" wrote:
"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"David Nebenzahl" wrote in message
ers.com...

Do you know *why* you can use just one neutral to serve two hots with
this kind of circuit?

If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole breaker,
you're going to have a tough time meeting Code with that monster circuit
you proposed.

The reason Code requires this is straightforward: the neutral wire carries
current. If one hot leg of a multiwire circuit is left powered on, and any
load on that leg is in use, the current drawn by that load is flowing in the
neutral -- presenting a risk of fatal electric shock to anyone servicing the
other leg of that circuit.

So are you saying that in a simple 3 wire bx cable, with the two hots
sharing a neutral, you'd need a two-pole breaker?

Correct -- not only for the reason I cited above, but also for another reason
which has already been discussed in this thread: to ensure that the two hots
are on opposite legs of the service.

If the two hots are on the *same* leg of the service, then the neutral could
be overloaded, because it will carry the *sum* of the currents in the hot
wires. This is a fire hazard.

"Pete C." wrote in message
ster.com...

Existential Angst wrote:

"David Nebenzahl" wrote in message
.com...
On 11/6/2009 11:08 PM Existential Angst spake thus:

If you have 20 2-wire bx cables stopping, say, 10 feet short of a 20
circuit panel, then, it seems to me, you can de facto *make* 10 edison
circuits up to the splice points, and therefore need only 10 neutrals
going between the panel and those 20 cables.

Thus, the edison circuit business is dependent on the actual *geometry
of
the wiring*, ie, "partial length" edison circuits are possible.

Thus, your seemingly restrictive "only circumstance" for two hot wires
sharing one neutral is in fact a fairly non-limiting requirement in
this
splicing circumstance, as ultimately, if a 20 circuit 240 V panel is
filled, you will *always* be able to make 10 edison circuits, for at
least part of the run.

So you do understand the concept of "Edison" circuits, right? That you
can't just grab any two hots, run a neutral with them and call it a
day?
Please tell us you understand this, or don't try it.

My first reply to dpk would indicate that I do understand edison
circuits.
Your previous post, and this one, indicate that you have a problem
understanding that I understand.


Do you know *why* you can use just one neutral to serve two hots with
this
kind of circuit?

If I didn't, would you tell me?

Here's the deal:

If the loads on each service leg are "balanced" (recall that vague
reference?), ie, electrically identical ito impedance, you wouldn't need
a
neutral at all. The total voltage applied to the two loads (effectively
in
series here) is 240 V, and the voltage drop across each load on a leg is
then 240/2 = 120 V, which is the appliance rating.

But what if one load is a 100 W bulb is on one leg, and a 1,000 W toaster
is
on another, and the neutral is lifted.
The voltage drop across the bulb is 10/11 * 240 and that across the
toaster
is 1/11 * 240. Thus, the bulb will burn out, but not the toaster.

Thus, the neutral acts as a kind of centertap for unbalanced loads on
each
leg, proly best analyzed with Thevenin's theorem -- in wiki, if anyone is
innerested, altho the sample problems there are not very illuminating.
Thevenin's theorem is essentially Ohm's Law on effing steroids....
wow.....

This Edison business explains why, in the presence of a a marginal or
inadequate neutral, adding or switching on another load will actually
make
lights *brighten*, because now current from one side of the svc is not
being
driven through a high-resistance neutral, and instead flows better
through
the now-balanced load on the other svc leg.

This neutral business clearly explains why 240 V appliances are
inherently
superior from an electrical loading pov -- both legs are balanced by
definition, and no neutral is required at all.
Plus, at 240 V, there is much less IR drop, and much less I^2R
transmission
loss. It's better all the way around.

Europe operates on 220-240 V, but according to one poster here, that is
between one leg and neutral, so they have the same "balancing problem" we
do, just at a higher voltage. The key is to have 240 V *between two hot
legs* -- and, of course, corresponding 240 V appliances.

Having said all this, I'll proly not go Edison-crazy, and just splice all
neutrals directly to the new panel. This way, there is no possibility of
future incompatibilities resulting from unwitting changes.

--
EA



--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

Perhaps just put a suitable pull box where the lines will reach, and
install a ground buss bar kit and an isolated neutral bus bar kit, and
tie them to the ground and neutral in the panel with appropriately sized
conductors. Since it's a short run, the same gauge as the panel neutral
and ground connections would certainly be sufficient.

When I have done this type of extension for a panel replacement, I have
normally done something like this for the grounds, but not the neutral.

Heh, this is exactly what I was contemplating! And alluded to when I
mentioned "neutral cross sectional area vs. total hot...."
I woulda been more explicit, but I didn't have a sufficiently fire-retardent
flame suit handy....

I proly will just run the individually spliced bx cables and their neutrals
to the panel, if for nothing else so the next person looking at the box
doesn't scream, WTF??!!!
Just more straightforward, less confusing in the electrical bookkeeping,
ultimately safer.

The original fuse box happens to have 6 three-wire bx cables, so when I hook
them up to the new breaker panel, I will make doubly sure the phases on each
of the wires in these cables is correct. Judging from how the lites dim in
some situations, I suspect they are not phased-up correctly!
--
EA

In article , "Existential Angst" wrote:

OK, one more clarification:
Said 3-wire bx cable, with two hots, one neutral, each hot on a sep. svc
leg, and each hot powering a 120V appliance, right?
Say, one hot for the microwave, and the other hot for the toaster, with
each neutral from that appliance's outlet/box being pigtailed together to
one neutral going back to the breaker panel. Good so far?

Good so far.

You would then put those two hots on a double pole breaker? So that if the
toaster goes out, the microwave goes out as well? Hmmmmm......

Code requirement as of the 2008 NEC.

In article , "Existential Angst" wrote:
[major snippage]
More often than not, in opening a junction box, esp. the larger 5" ones,
I'll see oodles of neutrals wire-nutted together, irrespective of the phase
of the hot leg. Apparently there is a wide-spread cavalier attitude toward
the lowly neutral.

More likely IMHO a failure to understand that the neutral carries current.
It's a Code violation, and a dangerous one, to connect the neutral of one
circuit to the neutral of another circuit unless the two are part of the same
multiwire circuit.

"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"David Nebenzahl" wrote in message
ters.com...

Do you know *why* you can use just one neutral to serve two hots with
this kind of circuit?

If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that
all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole
breaker,
you're going to have a tough time meeting Code with that monster circuit
you proposed.

The reason Code requires this is straightforward: the neutral wire
carries
current. If one hot leg of a multiwire circuit is left powered on, and
any
load on that leg is in use, the current drawn by that load is flowing in
the
neutral -- presenting a risk of fatal electric shock to anyone servicing
the
other leg of that circuit.

So are you saying that in a simple 3 wire bx cable, with the two hots
sharing a neutral, you'd need a two-pole breaker?

Correct -- not only for the reason I cited above, but also for another
reason
which has already been discussed in this thread: to ensure that the two
hots
are on opposite legs of the service.

If the two hots are on the *same* leg of the service, then the neutral
could
be overloaded, because it will carry the *sum* of the currents in the hot
wires. This is a fire hazard.

Indeed, I just posted that in my second response to Nate -- really very
inneresting.

Altho this job is really a pita, it is also an opportunity to perhaps remedy
some of this, as per my response to Pete.

This shared neutral business is a little reminiscent of the Ring Circuit,
brought up in a recent thread.
Altho of course different, the similarity to me is that both share a kind of
clever "slickness of economy", that can unfortunately backfire -- heh,
almost literally.

All in all, a super-illuminating thread, that will undoubtedly make this
project better and safer -- in fact, better and safer than the existing
state of this wiring.

--
EA

On Nov 7, 12:53*pm, (Doug Miller) wrote:
In article , "Existential Angst" wrote:

[major snippage]

More often than not, in opening a junction box, esp. the larger 5" ones,
I'll see oodles of neutrals wire-nutted together, irrespective of the phase
of the hot leg. *Apparently there is a wide-spread cavalier attitude toward
the lowly neutral.


It's perfectly normal to see several neutrals wire nutted together in
a junction box. Say a switch is going to serve 3 lights that have
seperate runs to them. In that box, the neutrals from each light run
would typically be tied together with the neutral coming into the box
from the breaker. So, you'd have 4 white neutral wires nutted
together.

That is distinctly seperate from two hots from two breakers sharing a
neutral in an edison circuit.





More likely IMHO a failure to understand that the neutral carries current..
It's a Code violation, and a dangerous one, to connect the neutral of one
circuit to the neutral of another circuit unless the two are part of the same
multiwire circuit.

On Nov 6, 2:20*pm, dpb wrote:
Existential Angst wrote:
Awl --

A two-part Q:

Due to some remodeling, I'm forced to splice/lengthen some old bx cable that
has #14 wire in it, and re-connect to the fuse box.
Should I splice the #14 with #14, or splice with #12?

The reason I would continue with #14 wire is just to remind me and future
people that Hey, this old wire is a little lighter than modern #12, and to
not take liberties with 20 or 30 amp fuses or breakers. *Other than that,
#12 would be fine with me.

There's nothing "unmodern" about 14 for 15A circuits.

I'd recommend sticking w/ same gauge as the original circuit for the
reason mentioned.

Remember to not bury connections in inaccessible places.

Next, *is there a rule of thumb for how many hot wires can share one neutral
of the same gauge? *If using different gauges, is there a "gauge ratio", ie,
some formula for cross sectional area between total hots and total neutrals?

Don't follow this question. *Each hot needs its own return neutral.
If you're talking about 3-wire ("Edison") circuits, if properly wired
the return is in effect a neutral w/ a balancing currents from the two
sides if both are loaded equally; hence only the same size conductor is
required for a single-sided load.

If that isn't it, I have no clue what you're thinking.

--

Agree completely. Also appears that the OP has some slightly odd ideas
about 'modern' versus 'older' wire gauges?????

To possibly keep discussion as simple a possible; recommend:
a) If existing wire is 14AWG, use 14AWG same as previous this will
help to remind anyone else who in the future works on the system that
the circuit incorporates 14AWG. (i.e. 15 amp).
b) Use only 15 amp fuses or breakers, especially if there is any doubt
that each/any circuit may contain any 14AWG. See personal note.
c) Likely that the OP would not understand an 'Edison' wired outlet
circuit. Let's omit and keep it simple.
Personal note: Realised some months before an insurance inspection
that we had wired a simple attached shed circuit comprising a single
bulb, a hanging 3 wire (L,N & G) and an external GFI garden outlet to
an existing lightly loaded 12AWG house outlet circuit that's been
there since 1970. We used a length of armour covered wire through the
outside wall and up to some 40 inches above floor, inside the shed,
which 'might' have been 14AWG! We promptly changed the breaker for
the whole circuit, back at the main panel, from 20 to 15 amp.
Inspector never looked at it! But at least we know it's safer and to
code!

"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"Doug Miller" wrote in message
...
In article , "Existential Angst"
wrote:
"David Nebenzahl" wrote in message
ters.com...

Do you know *why* you can use just one neutral to serve two hots with
this kind of circuit?

If I didn't, would you tell me?

Apparently you don't, so permit me to enlighten you. Code requires that
all
ungrounded (i.e. hot) conductors of a multiwire (Edison) circuit have a
*single* disconnecting means -- so unless you can find a 20-pole
breaker,
you're going to have a tough time meeting Code with that monster circuit
you proposed.

The reason Code requires this is straightforward: the neutral wire
carries
current. If one hot leg of a multiwire circuit is left powered on, and
any
load on that leg is in use, the current drawn by that load is flowing in
the
neutral -- presenting a risk of fatal electric shock to anyone servicing
the
other leg of that circuit.

So are you saying that in a simple 3 wire bx cable, with the two hots
sharing a neutral, you'd need a two-pole breaker?

Correct -- not only for the reason I cited above, but also for another
reason
which has already been discussed in this thread: to ensure that the two
hots
are on opposite legs of the service.

If the two hots are on the *same* leg of the service, then the neutral
could
be overloaded, because it will carry the *sum* of the currents in the hot
wires. This is a fire hazard.

Heh.... could always breaker the neutral!
--
EA

In article , wrote:

It's perfectly normal to see several neutrals wire nutted together in
a junction box. Say a switch is going to serve 3 lights that have
seperate runs to them. In that box, the neutrals from each light run
would typically be tied together with the neutral coming into the box
from the breaker. So, you'd have 4 white neutral wires nutted
together.

That's perfectly fine -- as long as they're all part of the same circuit.
Wire-nutting together the neutrals from two different circuits is not fine.

In article , "Existential Angst" wrote:
"Doug Miller" wrote in message
...


If the two hots are on the *same* leg of the service, then the neutral could
be overloaded, because it will carry the *sum* of the currents in the hot
wires. This is a fire hazard.

Heh.... could always breaker the neutral!

How do you plan to do that?

Existential Angst wrote:
....
So here's another Q:

Is a 3-wire bx cable leaving a panel *necessarily* an edison-type deal? Do
the two hots *always* have to be connected to separate phases? I would
think so, but I'm not absolutely sure. But I am going to put them on sep
phases regardless.

From the cable alone, "not necessarily" -- it _could_ be a 240V w/ third
conductor ground. Of course, it would still require the hots be on
opposite buses or there would be no potential between them and, of
course, the third conductor wouldn't be neutral but ground.

But, if'en this-here supposed cable is serving 110V circuits, then yes.
(Or at least at the moment I can't think of any alternative that would
be Code-compliant).

--

On 11/7/2009 11:51 AM Robert Green spake thus:

I believe the problem most people have with shared neutrals is that
it seems like they are adding 1 plus 1 and getting 1 as a result.
However, since they are out-of-phase, you're really adding 1/2 plus
1/2 and coming out with 1. When the first circuit's amplitude is at
its peak, the other phase is at the bottom, and the two phases cancel
each other out. It doesn't seem to be common sense that by adding a
load to the other half of unbalanced load that you'd actually be
reducing the current in the shared neutral wire, but that's how it
works. I think. (-: At least that's how my friend who designs 240VAC
gear explained it me.

That's 'zactly right.

Being 180° out of phase, any current running in one leg of the circuit
will be cancelled by any current in the other leg. The amount of
cancellation depends on the amount of current being drawn in each leg.
The highest current possible in the shared neutral will be when only one
leg is drawing maximum current. If both legs draw maximum current, then
the current in the neutral is close to zero. In this case, the majority
of the current flow is through the two "hot" wires.

Very clever idea. However, for reasons given here many times, I think
Edison circuits are to be avoided, on account of the potential problems
they can cause.

Spend the extra 25 cents and use paired hots and neutrals.


--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

On 11/7/2009 10:49 AM Existential Angst spake thus:

"Doug Miller" wrote in message
...

If the two hots are on the *same* leg of the service, then the
neutral could be overloaded, because it will carry the *sum* of the
currents in the hot wires. This is a fire hazard.

Heh.... could always breaker the neutral!

I know your tongue is in your cheek: however, while that would be a
clever way of making the circuit safe, at least fire-wise, I'm sure you
realize it could make it very, very unsafe, since it would possibly
leave an energized hot wire but a disconnected neutral.

But hey, it's a fun thought experiment.

(This is a similar problem to those very badly designed fuseboxes of
yesteryear that had fuses for both hot and neutral. My friend's house
has one of those, which can leave the hot energized but the neutral
disconnected. Wonder what genius came up with that design? His simple
but elegant solution is to overfuse the neutrals (w/30-amp fuses),
leaving 15 A fuses (actually circuit breakers in the form of a fuse) on
the hot side.)


--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

In article , "Existential Angst" wrote:

Is a 3-wire bx cable leaving a panel *necessarily* an edison-type deal?

No. It could supply an appliance that has both 240V and 120V loads. Examples
include electric dryers (240V heating elements, 120V motor and controls) and
electric stoves (240V heating elements, 120V controls).


Do the two hots *always* have to be connected to separate phases?

Well, no, not *always* -- one of them could be connected to nothing, I
suppose.

But if they're both connected, then yes, absolutely.

You can't get 240V unless they're on opposite legs of the service. And if
they're on the same leg, then the current in the neutral could be as much as
twice what it's rated for -- which is a potential fire hazard.

On 11/7/2009 10:47 AM Existential Angst spake thus:

In new construction, I'd be curious to know the ratio of #14 wired
houses vs #12 wired houses.
Given our energy gluttony, I'd hazard that #14 is used in more rural
areas, while #12 dominates in urban areas.

Not at all true. The houses I work on are all in a major metropolitan
area (San Francisco Bay area), and I'd say there's a pretty even mix of
15 and 20 amp circuits. Most electricians, it turns out, are not
complete idiots, and can judiciously allocate circuits to reduce costs
and conserve materials. So many lighting circuits, even in newer
construction, are 15 amps, while baseboard outlets, for example, are 20
amp circuits.

Then, of course, there are lots and lots of houses, as you can imagine,
with "mystery" circuits. I found one such on a customer's house not long
ago, a circuit on a 20-amp breaker that was *mostly* #12 except for a
short run I discovered that was #14. After scratching my head and
contemplating ripping a lot of **** out, I settled on a quick, cheap,
easy and safe fix: I swapped the breaker for a 15-amp one.


--
Who needs a junta or a dictatorship when you have a Congress
blowing Wall Street, using the media as a condom?

- harvested from Usenet

In article , "Robert Green" wrote:


[...] most of the 240VAC equipment in an
average home is not pure 240VAC. In my panel they run neutrals to power the
oven timers, water heater igniters and other circuits needing only 110VAC.

Electric water heaters have igniters?

Doug Miller wrote:
In article , "Robert Green" wrote:

[...] most of the 240VAC equipment in an
average home is not pure 240VAC. In my panel they run neutrals to power the
oven timers, water heater igniters and other circuits needing only 110VAC.

Electric water heaters have igniters?


Some gas water heaters have electric controls and igniters
similar to a gas furnace along with a draft inducer blower.

TDD

Existential Angst wrote:
....
As far as odd notions of wire gauge, prior to about 2000, I don't think NYC
made any general provision for #14 wire, except perhaps in special
circumstances.

I've never seen NYC Code, but that surely sounds suspicious--it would be
interesting to see reference to the Code requirements that ban it...

In new construction, I'd be curious to know the ratio of #14 wired houses vs
#12 wired houses.

Well, I don't think there is such a thing as a 14 vs 12 wired "house" as
a general rule; there are 12 and 14 circuits generally in the same house
in quite high proportions I'm sure. General lighting is typically 15A
while outlets, etc., kitchens/baths are 20A.

Given our energy gluttony, I'd hazard that #14 is used in more rural areas,
while #12 dominates in urban areas.

That's as urban-mythic and urban-centric a statement as something one
hear out hear about inner cities or somesuch. There's no shortage of
power and amenities in new construction out here in the hinterlands
although it is sometimes necessary to wait for the stage from Dodge for
the mail.

--

The Daring Dufas wrote:
Doug Miller wrote:
In article , "Robert Green"
wrote:

[...] most of the 240VAC equipment in an
average home is not pure 240VAC. In my panel they run neutrals to
power the
oven timers, water heater igniters and other circuits needing only
110VAC.

Electric water heaters have igniters?


Some gas water heaters have electric controls and igniters
similar to a gas furnace along with a draft inducer blower.

TDD

right, but a gas water heater wouldn't need a 240VAC circuit to serve
it, either. So still only 2 wires plus ground.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel