Hello,

I don't expect responders to be intimately familiar w/CA electrical code but
is what's described below generally done?

I want to run two 120V/20A circuits into my shop. I would like every outlet
to use both circuits. I've read that splitting an outlet among two circuits
requires a special breaker in the panel so let's assume that I will just use
two dual outlets per receptacle with the outlet on the left being on one
circuit and the one on the right being on the other.

The question is can I run this using a single run of 3 wire cable running
white to the neutral bar, black to one 20A breaker and red to another 20A
breaker. I.e. the two circuits share a neutral and ground wire.

This seems reasonable to me since the neutrals and grounds are tied to the
same potential at the panel anyway but I imagine many a house has caught
fire due to things that seemed reasonable at the time.

thanks for the help
ml

I don't expect responders to be intimately familiar w/CA electrical code
but
is what's described below generally done?

I want to run two 120V/20A circuits into my shop. I would like every
outlet
to use both circuits. I've read that splitting an outlet among two
circuits
requires a special breaker in the panel so let's assume that I will just
use
two dual outlets per receptacle with the outlet on the left being on one
circuit and the one on the right being on the other.

The question is can I run this using a single run of 3 wire cable running
white to the neutral bar, black to one 20A breaker and red to another 20A
breaker. I.e. the two circuits share a neutral and ground wire.

This seems reasonable to me since the neutrals and grounds are tied to the
same potential at the panel anyway but I imagine many a house has caught
fire due to things that seemed reasonable at the time.

That is called a multiwire circuit; it is essentially a 240v circuit used
for 2 120v circuits. It is fine as long as you use a 240v breaker. 2 120v
breakers are potentially dangerous because you can forget to shut one off
before working on the outlet, and you can carelessly put both on the same
leg of the breaker box; these careless acts are prevented by a 240v breaker.

On my house they actually did use 2 120v breakers on the same leg.
Fortunately they were not heavily used circuits, so it didn't matter; but it
could easily have caused a fire.

I suppose using two outlets would be safer if you are hell bent on using
120v breakers rather than a 240v; but seems klunky. Why not do it right?

wrote:
Hello,

I don't expect responders to be intimately familiar w/CA electrical
code but is what's described below generally done?

I want to run two 120V/20A circuits into my shop. I would like every
outlet to use both circuits. I've read that splitting an outlet
among two circuits requires a special breaker in the panel so let's
assume that I will just use two dual outlets per receptacle with the
outlet on the left being on one circuit and the one on the right
being on the other.

The question is can I run this using a single run of 3 wire cable
running white to the neutral bar, black to one 20A breaker and red to
another 20A breaker. I.e. the two circuits share a neutral and
ground wire.

This seems reasonable to me since the neutrals and grounds are tied
to the same potential at the panel anyway but I imagine many a house
has caught fire due to things that seemed reasonable at the time.

thanks for the help
ml

First problem I see is that you appear to lack some basic knowledge
about what you are planning. That makes me wonder if you have the knowledge
and skills to do the rest of the job. At the very least get a good book
that covers this information. Newsgroups are not going to be able to
provide you with all the knowledge you will need to do the job properly and
safely.

Yes you can use two circuits on the cable you are looking at. Is it 12
gauge copper??? I don't recall if you can use it for what you are planning.
I would want to check the code first. I'll bet someone will address that
issue on the newsgroup. HOWEVER. To do what you want to do you must have
each wire (red & black) on a opposite phases. This is normally assured by
using a special breaker that will make sure you do that and will also assure
that both sides will go dead when you turn one off. It would be very easy
for someone not knowing how it was wired to turn off one circuit and test
one socket to assure it was dead and then open up a box not knowing half the
wires were hot.

Frankly you may want to consider a professional.

--
Joseph Meehan

Dia duit

In article Q4Pbe.33$g71.0@fed1read02, wrote:
I don't expect responders to be intimately familiar w/CA electrical code but
is what's described below generally done?

It's called a multiwire branch circuit, or Edison circuit. I don't know if
this is permitted by the CEC, but it *is* permitted under the NEC in the
United States, subject to certain provisions. It's up to you to determine if
this is permitted in Canada, and under what provisions.

I want to run two 120V/20A circuits into my shop. I would like every outlet
to use both circuits. I've read that splitting an outlet among two circuits
requires a special breaker in the panel so let's assume that I will just use
two dual outlets per receptacle with the outlet on the left being on one
circuit and the one on the right being on the other.

Same issues, really. The main difference is that, with two separate
receptacles, the second provision listed below is *not* a requirement of the
U.S. NEC, whereas it *is* a requirement with a single duplex receptacle. The
requirements may be different in Canada; and in any event, it's still a damn
good idea even if the Code doesn't require it.

The question is can I run this using a single run of 3 wire cable running
white to the neutral bar, black to one 20A breaker and red to another 20A
breaker. I.e. the two circuits share a neutral and ground wire.

Yes, IF:
a) the two breakers are on *opposite* legs of the 240V service, AND
b) there is a common disconnecting means (i.e. trip one breaker and they both
go off).

Using a single 240V (two-pole) breaker satisfies both of those requirements,
and is by far the easiest and safest way to install such a circuit.

This seems reasonable to me since the neutrals and grounds are tied to the
same potential at the panel anyway but I imagine many a house has caught
fire due to things that seemed reasonable at the time.

It is reasonable, and safe (if done correctly), but that has NOTHING to do
with the neutrals and grounds being at the same potential in the panel. The
reason it's safe is that when the two hots are on opposite legs of the
service, the current in the neutral wire is the *difference* between the
currents in the two hot wires. If you put the two hots on the *same* leg of
the service, the current in the neutral is the *sum* of the currents in the
two hot lets, and the neutral can very easily become overloaded and start a
fire.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

wrote:

Hello,

I don't expect responders to be intimately familiar w/CA electrical code but
is what's described below generally done?

I want to run two 120V/20A circuits into my shop. I would like every outlet
to use both circuits. I've read that splitting an outlet among two circuits
requires a special breaker in the panel so let's assume that I will just use
two dual outlets per receptacle with the outlet on the left being on one
circuit and the one on the right being on the other.

The question is can I run this using a single run of 3 wire cable running
white to the neutral bar, black to one 20A breaker and red to another 20A
breaker. I.e. the two circuits share a neutral and ground wire.

This seems reasonable to me since the neutrals and grounds are tied to the
same potential at the panel anyway but I imagine many a house has caught
fire due to things that seemed reasonable at the time.

thanks for the help
ml

Does your cable have a ground wire? You said 3 conductors, but then you
mentioned black, white, and red and didn't say anything about bare or
green. I assume you meant 12/3 cable, and a ground conductor is understood.

Use a 240v breaker so your black and red wire are forced to be on
opposite legs and to provide a common trip and it'll work just fine.

Best regards,
Bob

On 27-Apr-2005, (Doug Miller) wrote:

t is reasonable, and safe (if done correctly), but that has NOTHING to do
with the neutrals and grounds being at the same potential in the panel.
The
reason it's safe is that when the two hots are on opposite legs of the
service, the current in the neutral wire is the *difference* between the
currents in the two hot wires. If you put the two hots on the *same* leg
of
the service, the current in the neutral is the *sum* of the currents in
the
two hot lets, and the neutral can very easily become overloaded and start
a
fire.

I understand. Hence the need for a 240V breaker to ensure that the circuits
are on opposite legs.

Ok, so wiring two circuits w/one cable is probably permissible pending check
of CA code, given that I use a 240V breaker wiring the hots to each side of
it to ensure they are opposite in phase and to ensure both circuits are
simultaneously shut off via a single switch.

It sounds like it's simply worth running two cables so that I can have one
circuit if there is ever a problem on the other.

thank you all for your responses.
doing things right the first time is why i read books and ask questions

On Wed, 27 Apr 2005 17:28:08 GMT, wrote:


On 27-Apr-2005, (Doug Miller) wrote:

t is reasonable, and safe (if done correctly), but that has NOTHING to do
with the neutrals and grounds being at the same potential in the panel.
The
reason it's safe is that when the two hots are on opposite legs of the
service, the current in the neutral wire is the *difference* between the
currents in the two hot wires. If you put the two hots on the *same* leg
of
the service, the current in the neutral is the *sum* of the currents in
the
two hot lets, and the neutral can very easily become overloaded and start
a
fire.

I understand. Hence the need for a 240V breaker to ensure that the circuits
are on opposite legs.

Ok, so wiring two circuits w/one cable is probably permissible pending check
of CA code, given that I use a 240V breaker wiring the hots to each side of
it to ensure they are opposite in phase and to ensure both circuits are
simultaneously shut off via a single switch.

It sounds like it's simply worth running two cables so that I can have one
circuit if there is ever a problem on the other.

thank you all for your responses.
doing things right the first time is why i read books and ask questions

In article X_Pbe.25$rJ1.21@fed1read02, wrote:

On 27-Apr-2005, (Doug Miller) wrote:

t is reasonable, and safe (if done correctly), but that has NOTHING to do
with the neutrals and grounds being at the same potential in the panel.
The
reason it's safe is that when the two hots are on opposite legs of the
service, the current in the neutral wire is the *difference* between the
currents in the two hot wires. If you put the two hots on the *same* leg
of
the service, the current in the neutral is the *sum* of the currents in
the
two hot lets, and the neutral can very easily become overloaded and start
a
fire.

I understand. Hence the need for a 240V breaker to ensure that the circuits
are on opposite legs.

And to make sure that *both* hot conductors are disconnected at the same time.

Ok, so wiring two circuits w/one cable is probably permissible pending check
of CA code, given that I use a 240V breaker wiring the hots to each side of
it to ensure they are opposite in phase and to ensure both circuits are
simultaneously shut off via a single switch.

Right..

It sounds like it's simply worth running two cables so that I can have one
circuit if there is ever a problem on the other.

Maybe. If you use two separate circuits, but put one receptacle from each
circuit in the *same* two-gang box, it's still a *very* good idea, from a
safety standpoint, to have a common disconnect anyway even though the NEC
doesn't require it. And for all I know, the CEC might require it. And if you'd
be shutting down both circuits anyhow to fix a problem on one, you might as
well run the multiwire circuit.

The biggest advantage to using two separate circuits is that it makes using
GFCIs a whole lot simpler.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

On 27-Apr-2005, (Doug Miller) wrote:

Maybe. If you use two separate circuits, but put one receptacle from each
circuit in the *same* two-gang box, it's still a *very* good idea, from a
safety standpoint, to have a common disconnect anyway even though the NEC
doesn't require it.

agreed. now that I'm thinking about the next guy to work on this I would
just alternate
spaced outlet receptacles on the two circuits... having the receptacles on
each circuit
at a slightly different height sounds like a good idea as well.

agreed. now that I'm thinking about the next guy to work on this I would
just alternate
spaced outlet receptacles on the two circuits... having the receptacles on
each circuit
at a slightly different height sounds like a good idea as well.


I've got one lab that I work on that's got one row of outlets
at a standard 16" above the floor, and another row just over desk
height. Depending on what you want all that power for,
this is a good time to think about whether you want totally separate
circuts. (Maybe at ceiling height, too, if you've got high-mounted
equipment.)

Doug Miller wrote:

It's called a multiwire branch circuit, or Edison circuit. I don't know if
this is permitted by the CEC, but it *is* permitted under the NEC...

On a related note, I wonder if UK-style "ring mains" are legal under CEC
or NEC. The hot wire leaves the breaker, connects to a ring of outlets,
THEN RETURNS to the breaker. This reduces the average wiring power loss
without adding much wire, and if the wire breaks in one place, all the
outlets keep working.

Nick

wrote:
Doug Miller wrote:

It's called a multiwire branch circuit, or Edison circuit. I don't
know if this is permitted by the CEC, but it *is* permitted under
the NEC...

On a related note, I wonder if UK-style "ring mains" are legal under
CEC or NEC. The hot wire leaves the breaker, connects to a ring of
outlets, THEN RETURNS to the breaker. This reduces the average wiring
power loss without adding much wire, and if the wire breaks in one
place, all the outlets keep working.

Nick

An interesting question. I don't think so, but I sure don't know.

--
Joseph Meehan

Dia duit

wrote:
Hello,

I don't expect responders to be intimately familiar w/CA electrical
code but
is what's described below generally done?

I want to run two 120V/20A circuits into my shop. I would like every
outlet
to use both circuits. I've read that splitting an outlet among two
circuits
requires a special breaker in the panel so let's assume that I will
just use
two dual outlets per receptacle with the outlet on the left being on
one
circuit and the one on the right being on the other.

The question is can I run this using a single run of 3 wire cable
running
white to the neutral bar, black to one 20A breaker and red to another
20A
breaker. I.e. the two circuits share a neutral and ground wire.

This seems reasonable to me since the neutrals and grounds are tied
to the
same potential at the panel anyway but I imagine many a house has
caught
fire due to things that seemed reasonable at the time.

thanks for the help
ml

This is legal in both Canada and the US, and is the traditional way
Canadian kitchens were mandated to be wired (at 15A, not necessarily
20A) until recently. The "special breaker" is a dual-pole unit, aka
240V breaker, and you need it whether you put two duplex outlets
together or one outlet with the tie bar broken on the hot side. The
latter is the common, usual way to do it, and is called a "split
receptacle" scheme.

The dual-pole breaker guarantees two important things: (a) the two hots
will be on opposite legs, so the current cancels in the neutral instead
of adds, and (b) one breaker will trip the other. I believe feature (b)
is legally required only in the case of a split receptacle, not in the
case of alternating duplex receptacles.

If it's all 12 gauge on a 20A breaker you can make the outlets the new
(to Canada) T-slot type, but this is (I believe) not required. There is
little practical advantage since no device known to mankind has a 20A
plug on it. (When I asked if this was true, I got no replies, so I'll
state it as bald fact and maybe someone will offer a counterexample.)

Another factino that may or may not be of interest: if the circuit has
any light fixtures on it, you may use only a 15 A breaker, even if all
the wiring is 12 ga. This is an oddity of Canadian code only, I
believe. But a workshop circuit is a poor choice to put lighting on
anyhow.

Chip C
Toronto

wrote:
Doug Miller wrote:

It's called a multiwire branch circuit, or Edison circuit. I don't
know if
this is permitted by the CEC, but it *is* permitted under the NEC...

On a related note, I wonder if UK-style "ring mains" are legal under
CEC
or NEC. The hot wire leaves the breaker, connects to a ring of
outlets,
THEN RETURNS to the breaker. This reduces the average wiring power
loss
without adding much wire, and if the wire breaks in one place, all
the
outlets keep working.

Nick

I'm pretty darn sure that's a big No, that it's a requirement that ONE
breaker be able to shut down the whole circuit.

Chip C
Toronto

Chip C wrote:

...I wonder if UK-style "ring mains" are legal under CEC or NEC.
The hot wire leaves the breaker, connects to a ring of outlets,
THEN RETURNS to the breaker. This reduces the average wiring power
loss without adding much wire, and if the wire breaks in one place,
all the outlets keep working.

I'm pretty darn sure that's a big No, that it's a requirement that ONE
breaker be able to shut down the whole circuit.

It would, if the wire returns to the same breaker.

Nick

) said...

Ok, so wiring two circuits w/one cable is probably permissible pending check
of CA code, given that I use a 240V breaker wiring the hots to each side of
it to ensure they are opposite in phase and to ensure both circuits are
simultaneously shut off via a single switch.

It sounds like it's simply worth running two cables so that I can have one
circuit if there is ever a problem on the other.

There are two advantages of running a 3-wire cable that may make you want
to not consider the separate cable option...

First, in a split outlet (common in kitchens here in Canada) the top and
bottom half can provide the full circuit load current if needed. If you
had the situation where you needed to operate two heavy loads near each
other, you could plug them both into the same outlet without the fear of
tripping a breaker.

Second, if you ever found you had the need to install a 240 volt outlet
(with the same current rating), you could easily replace the split 120
volt outlet with the 240 volt outlet.

--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be explained by incompetence."
- Napoleon
-------------------------------------------------------------------------
NOTE: if replying by email, remove "remove." and ".invalid"

Doug Miller ) said...

Maybe. If you use two separate circuits, but put one receptacle from each
circuit in the *same* two-gang box, it's still a *very* good idea, from a
safety standpoint, to have a common disconnect anyway even though the NEC
doesn't require it. And for all I know, the CEC might require it.

The CEC probably does not require it, since the CEC (believe it or not)
does not require a common disconnect for a multi-wire circuit unless it
is feeding the same device (like a 120/240 volt appliance, or a split
outlet).

The 1994 revision to the CEC allowed you to use two separate single-pole
breakers (provided they are on opposite hots) to protect a multi-wire
cable feeding two circuits -- for instance, a 14/3 cable used for the
home run, then splitting to two separate 14/2 cables for each circuit.

I mention this, not from my own interpretation of the code, but I attended
a new code seminar when this came out and the inspector leading the
group described this quite clearly, and was asked to repeat this by a
number of disbelievers, myself included.

Personally, I follow the rule that all conductors "enclosed together".

--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be explained by incompetence."
- Napoleon
-------------------------------------------------------------------------
NOTE: if replying by email, remove "remove." and ".invalid"

I want to do the same thing using the 12-3 wire for the long run from the
circuit box then 12-2 on to each of two separate circuits. Assuming all of
the 240 breaker issues are taken care of is there any problem with that
either safety practical or code approval (I am in NJ).

In article , lid (Calvin Henry-Cotnam) wrote:

Second, if you ever found you had the need to install a 240 volt outlet
(with the same current rating), you could easily replace the split 120
volt outlet with the 240 volt outlet.

Don't know about Canada... but in the U.S. the NEC _explicitly_prohibits_
mixing 240V and 120V loads on a multiwire circuit.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

In article , lid (Calvin Henry-Cotnam) wrote:
Doug Miller ) said...

Maybe. If you use two separate circuits, but put one receptacle from each
circuit in the *same* two-gang box, it's still a *very* good idea, from a
safety standpoint, to have a common disconnect anyway even though the NEC
doesn't require it. And for all I know, the CEC might require it.

The CEC probably does not require it, since the CEC (believe it or not)
does not require a common disconnect for a multi-wire circuit unless it
is feeding the same device (like a 120/240 volt appliance, or a split
outlet).

Yep, the NEC is the same. Foolishly so IMO, but they didn't ask me first. :-)

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

In article , "new" wrote:
I want to do the same thing using the 12-3 wire for the long run from the
circuit box then 12-2 on to each of two separate circuits. Assuming all of
the 240 breaker issues are taken care of is there any problem with that
either safety practical or code approval (I am in NJ).

Safety, practicality - you're fine.
Code approval - maybe, maybe not. The National Electrical Code permits that.
But not all jurisdictions have adopted the NEC for their local code. Some have
adopted the NEC with restrictions. It varies all over the place. The only way
to know what is acceptable where you live is to ask the code inspectors where
you live. Knowing that you're in NJ isn't necessarily much help, as it could
vary considerably from one place to the next within the same state.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

=== inline
wrote in message news:Q4Pbe.33$g71.0@fed1read02...
Hello,
....
I want to run two 120V/20A circuits into my shop. I would like every
outlet
to use both circuits. I've read that splitting an outlet among two
circuits
requires a special breaker in the panel so let's assume that I will just
use
two dual outlets per receptacle with the outlet on the left being on one
circuit and the one on the right being on the other.
=== True; that's one way to do it. Each of the two hots have 120Vac on
them, just 180° out of phase.
Just be certain you take the red/black to opposite phased connections in
the breaker panel. Usually they alternate per breaker; use a meter to be
certain. 240V = two phases. 0V (or nearly 0) indicates same phase. You
want both phases, one on red, other on black.

BUT, if you're talking about ONE Duplex outlet, one with TWO receptacles,
and having each receptacle in the duplex outlet on a different breaker, you
also need to be sure you isolate the two receptacles in the duplex outlet
by breaking the bar that connects them together.


The question is can I run this using a single run of 3 wire cable running
white to the neutral bar, black to one 20A breaker and red to another 20A
breaker. I.e. the two circuits share a neutral and ground wire.
=== Yes. Because of the phase difference between the two lines, one does
not linearly add to the other; they only add by phase relationship and thus
will never put excessive current into the neutral or earth.

This seems reasonable to me since the neutrals and grounds are tied to the
same potential at the panel anyway but I imagine many a house has caught
fire due to things that seemed reasonable at the time.
=== Well, they're at the same "potential", but not at the same time. If
you've wired it right, one is at 0 when the other is at 120, and vice versa,
so at any instant in time current is 20A in your case. _-_-_-_-
If you put the wires on the SAME phase, then each could carry 20A and you
would have double the current flowing in the neutral and that wouldn't meet
code since it would be possible to put 40A in the neutral wire.

It's really much better to run one cable for each outlet, from two breakers.
Easier to identify, and easier to keep straight when you're doing the
wiring, too.
Then you don't have to worry about getting the phases right. This is
oversimplified, but: red to black is intended to be 240Vac difference
between them. Black\white is intended to have 120Vac between them.

Pop

thanks for the help
ml

wrote:
On 27-Apr-2005, (Doug Miller) wrote:


t is reasonable, and safe (if done correctly), but that has NOTHING to do
with the neutrals and grounds being at the same potential in the panel.
The
reason it's safe is that when the two hots are on opposite legs of the
service, the current in the neutral wire is the *difference* between the
currents in the two hot wires. If you put the two hots on the *same* leg
of
the service, the current in the neutral is the *sum* of the currents in
the
two hot lets, and the neutral can very easily become overloaded and start
a
fire.


I understand. Hence the need for a 240V breaker to ensure that the circuits
are on opposite legs.

Ok, so wiring two circuits w/one cable is probably permissible pending check
of CA code, given that I use a 240V breaker wiring the hots to each side of
it to ensure they are opposite in phase and to ensure both circuits are
simultaneously shut off via a single switch.

It sounds like it's simply worth running two cables so that I can have one
circuit if there is ever a problem on the other.

thank you all for your responses.
doing things right the first time is why i read books and ask questions

You can still run a single cable. there is cable available that has two
separate neutrals as well as two ungrounded conductors and one ground in
the same cable jacket. The only advantage is the effort saved in not
running two cables. One such cable had a black, red, white with black
tracer, white with red tracer, and a bare ground. The cable was
developed to save labor on runs serving bedrooms that are required to
have AFCI protection which prevents using Edison circuits because AFCIs
are not yet available for those circuits.
--
Tom H

Doug Miller ) said...

Don't know about Canada... but in the U.S. the NEC _explicitly_prohibits_
mixing 240V and 120V loads on a multiwire circuit.

Interesting. I can't say I have seen this prohibition in our code, at
least for residential dwellings, but I have done it on occasion without
problems from inspectors.

We have a cold storage room and I wanted to put in a small (300W) baseboard
heater with a thermostat just above the freezing mark just to prevent
freezing if we were hit with a real cold spell. The room needed lighting
and I wanted an outlet, so I ran a 120/240 volt circuit that powers the
light on one leg, the outlet on the other, and the heater using both. The
inspector approved it.

Also, at my parents house they have a pool pump that is configured for
240 volt operation and one leg of the circuit provides power to an outlet
and some lights in the yard. To add to it, a few years back when we were
renovating the kitchen and needed to add some new circuits, I asked the
inspector about using the other leg of that circuit to power the garbage
disposal and he had no problems with us doing that.

As long as you are within the 80% loading rule, there's no problem here.

--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be explained by incompetence."
- Napoleon
-------------------------------------------------------------------------
NOTE: if replying by email, remove "remove." and ".invalid"

Doug Miller ) said...

In article ,
lid (Calvin Henry-Cotnam) wrote:
Doug Miller ) said...

Maybe. If you use two separate circuits, but put one receptacle from each
circuit in the *same* two-gang box, it's still a *very* good idea, from a
safety standpoint, to have a common disconnect anyway even though the NEC
doesn't require it. And for all I know, the CEC might require it.

The CEC probably does not require it, since the CEC (believe it or not)
does not require a common disconnect for a multi-wire circuit unless it
is feeding the same device (like a 120/240 volt appliance, or a split
outlet).

Yep, the NEC is the same. Foolishly so IMO, but they didn't ask me first. :-)

Same here. ;-)

Come to think of it, it is more foolishly considering the existence of
mini-breakers (or twin, or half-size) that squeeze two breakers into one
position -- in the case of those, two side-by-side breakers are not
necessarily on opposite legs!

--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be explained by incompetence."
- Napoleon
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NOTE: if replying by email, remove "remove." and ".invalid"

On 28-Apr-2005, wrote:

Hire an electrician to change light bulbs, and hire an electrician to
turn
ON or OFF all circuit breakers in non-emergency situations.

I'll get right on that. I think I'll hire a plumber to flush the toilet for
me as well. Can never be too careful.

According to :
Ok, so wiring two circuits w/one cable is probably permissible pending check
of CA code, given that I use a 240V breaker wiring the hots to each side of
it to ensure they are opposite in phase and to ensure both circuits are
simultaneously shut off via a single switch.

It's legal in Canada. In fact, until recently, it was the _only_ way
to wire kitchen counter outlets.

It sounds like it's simply worth running two cables so that I can have one
circuit if there is ever a problem on the other.

_Not_ in the same outlet box.

12/3 with split receptacles is the way to go.

I wired my shop that way.

The Canadian inspectors were quite happy.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

On Thu, 28 Apr 2005 00:01:25 GMT, (Doug Miller)
wrote:

In article , lid (Calvin Henry-Cotnam) wrote:

Second, if you ever found you had the need to install a 240 volt outlet
(with the same current rating), you could easily replace the split 120
volt outlet with the 240 volt outlet.

Don't know about Canada... but in the U.S. the NEC _explicitly_prohibits_
mixing 240V and 120V loads on a multiwire circuit.



Well, that makes sense, if you're allowed to have two un-tied
breakers feeding different legs. All *KINDS* of fun things
can happen if you pull one breaker of a mixed circut like that.
Starting with but not limited to melting any motor-driven
equipment anywhere on the loop, and ending with presenting
you with line current in a box you just pulled the breaker on.

According to Calvin Henry-Cotnam :

The 1994 revision to the CEC allowed you to use two separate single-pole
breakers (provided they are on opposite hots) to protect a multi-wire
cable feeding two circuits -- for instance, a 14/3 cable used for the
home run, then splitting to two separate 14/2 cables for each circuit.

I mention this, not from my own interpretation of the code, but I attended
a new code seminar when this came out and the inspector leading the
group described this quite clearly, and was asked to repeat this by a
number of disbelievers, myself included.

Personally, I follow the rule that all conductors "enclosed together".

Egad, and this was one place where I thought the CEC was smarter than the
NEC.

Sheesh.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:

12/3 with split receptacles is the way to go.

I wired my shop that way.

The Canadian inspectors were quite happy.


Just curious, but could you put a 240V convenience outlet on that
multiwire branch circuit without ****ing off the inspectors? That could
be quite handy in a shop.

Best regards,
Bob

According to Calvin Henry-Cotnam :
Doug Miller ) said...

Don't know about Canada... but in the U.S. the NEC _explicitly_prohibits_
mixing 240V and 120V loads on a multiwire circuit.

Interesting. I can't say I have seen this prohibition in our code, at
least for residential dwellings, but I have done it on occasion without
problems from inspectors.

The CEC does prohibit it. It's just that with a multi-wire branch with
only one receptacle, you'd not be "mixing voltages" if you swapped it to 240V.

We have a cold storage room and I wanted to put in a small (300W) baseboard
heater with a thermostat just above the freezing mark just to prevent
freezing if we were hit with a real cold spell. The room needed lighting
and I wanted an outlet, so I ran a 120/240 volt circuit that powers the
light on one leg, the outlet on the other, and the heater using both. The
inspector approved it.

The inspector likely approved it because the circuit wasn't "general
purpose".

Also, at my parents house they have a pool pump that is configured for
240 volt operation and one leg of the circuit provides power to an outlet
and some lights in the yard. To add to it, a few years back when we were
renovating the kitchen and needed to add some new circuits, I asked the
inspector about using the other leg of that circuit to power the garbage
disposal and he had no problems with us doing that.

Now _that_ is somewhat strange.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

According to Chip C :

The dual-pole breaker guarantees two important things: (a) the two hots
will be on opposite legs, so the current cancels in the neutral instead
of adds,

There are _some_ panels where a dual breaker does not guarantee
opposite legs. Ie: certain Federal Pioneer/Pacific panels, where
it's possible to install a regular dual breaker and both
breakers are on the same leg.

You should examine the backplane carefully (or use a voltmeter)
to be sure.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

According to zxcvbob :
Chris Lewis wrote:

12/3 with split receptacles is the way to go.

I wired my shop that way.

The Canadian inspectors were quite happy.

Just curious, but could you put a 240V convenience outlet on that
multiwire branch circuit without ****ing off the inspectors? That could
be quite handy in a shop.

You couldn't have both 240V and 120V outlets on the same circuit.

[Henry thinks differently, but unless our code has changed in this
regard since my copy, CEC still prohibits mixed voltages. I believe
the exceptions he encountered was an inspector giving him a break
on a very specific situation.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

wrote:
Chip C wrote:

...I wonder if UK-style "ring mains" are legal under CEC or NEC.
The hot wire leaves the breaker, connects to a ring of outlets,
THEN RETURNS to the breaker. This reduces the average wiring power
loss without adding much wire, and if the wire breaks in one place,
all the outlets keep working.

I'm pretty darn sure that's a big No, that it's a requirement that
ONE
breaker be able to shut down the whole circuit.

It would, if the wire returns to the same breaker.

Nick

Oh yeah; somehow I had it in my head that the ends are on separate
breakers.

(I guess in the UK the breakers have two wiring connections for this
purpose?)

So now I'm pretty darn sure that's a big I Haven't A Clue.

Chip C

According to Chip C :

If it's all 12 gauge on a 20A breaker you can make the outlets the new
(to Canada) T-slot type, but this is (I believe) not required. There is
little practical advantage since no device known to mankind has a 20A
plug on it. (When I asked if this was true, I got no replies, so I'll
state it as bald fact and maybe someone will offer a counterexample.)

I'd be willing to assume that there hasn't been any devices _in_ Canada
with those plugs pre-installed... ;-) Because, until recently, those
T-slot receptacles were illegal, and what _few_ 120V/20A circuits there
were, were almost always hard-wired, and didn't even have non-T'd
20A receptacles.

There must be some equipment out there with aftermarket 20A plugs on
them, because you _can_ buy them ;-)
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:
According to Chip C :


If it's all 12 gauge on a 20A breaker you can make the outlets the new
(to Canada) T-slot type, but this is (I believe) not required. There is
little practical advantage since no device known to mankind has a 20A
plug on it. (When I asked if this was true, I got no replies, so I'll
state it as bald fact and maybe someone will offer a counterexample.)


I'd be willing to assume that there hasn't been any devices _in_ Canada
with those plugs pre-installed... ;-) Because, until recently, those
T-slot receptacles were illegal, and what _few_ 120V/20A circuits there
were, were almost always hard-wired, and didn't even have non-T'd
20A receptacles.

There must be some equipment out there with aftermarket 20A plugs on
them, because you _can_ buy them ;-)


Window air conditioners, about 15000 to 18000 BTU/hr.

Best regards,
Bob

In article , Goedjn wrote:
On Thu, 28 Apr 2005 00:01:25 GMT, (Doug Miller)
wrote:

Don't know about Canada... but in the U.S. the NEC _explicitly_prohibits_
mixing 240V and 120V loads on a multiwire circuit.

Well, that makes sense, if you're allowed to have two un-tied
breakers feeding different legs. All *KINDS* of fun things
can happen if you pull one breaker of a mixed circut like that.

Right - and I need to amend my statement above, which should have read "...
prohibits mixing 240V and 120V loads on a multiwire circuit unless there's a
single-point disconnect."

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

Chris Lewis ) said...

According to Chip C :

The dual-pole breaker guarantees two important things: (a) the two hots
will be on opposite legs, so the current cancels in the neutral instead
of adds,

There are _some_ panels where a dual breaker does not guarantee
opposite legs. Ie: certain Federal Pioneer/Pacific panels, where
it's possible to install a regular dual breaker and both
breakers are on the same leg.

Chip's wording should be: "two pole" breaker, not "dual".

A two pole breaker will guarantee opposite legs, and will have a common
trip (tied handles).

"Dual" simply means there are two in one housing, and given the presence
of mini-breakers (where two fit in the space of one, and are therefore
fed from the same leg!), one must check to be sure.

--
Calvin Henry-Cotnam
"Never ascribe to malice what can equally be explained by incompetence."
- Napoleon
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NOTE: if replying by email, remove "remove." and ".invalid"

According to Calvin Henry-Cotnam :
A two pole breaker will guarantee opposite legs, and will have a common
trip (tied handles).

I _meant_ "a two pole breaker does NOT necessarily guarantee opposite legs".

A certain not-ancient generation/model of Canadian Federal Pacific panel
(Federal Pioneer in the US) had (has?) the breaker backplane having the legs
sequenced as "AABBAABB".

Which meant that a full size standard two pole breaker with integral tiebar
could (can?) be installed such that both breakers are on the same leg.

During a renovation for a friend (new panels), I switched their stove
over to the new panel on a FP two pole breaker. I had noticed the
odd backplane arrangement, and had to be careful about slot allocation
because of it.

Tested stove, worked fine.

The next day, my friend called me and told me that only the stove
clock and stove accessory receptacle were working, nothing else was - no
heat.

It was a long trip to their house, and we weren't planning on going there
for a while, but they needed the stove.... Just before sighing,
hanging up, and travelling down there, he casually mentioned
that he had pulled the breaker for some reason then reinstalled it.

Bing!

He slid it over a slot, and the stove started working again.

When you first start doing 240V work on a panel, you should double check the
backplane arrangement to be _sure_ it's not dumb like that FP panel was.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.