On Jun 22, 7:21*pm, bud-- wrote:
wrote:
On Jun 22, 9:51 am, Tony Hwang wrote:
Pavel314 wrote:
This is a theoretical electrical question, not something I actually
plan to do. Say somebody wants to run a new circuit from the breaker
box to one special outlet, like for a microwave oven or window air
conditioner or something like that. Being an ecconomical sort, this
guy decides that instead of buying the proper gauge wire for the job,
he'll use up some 14 gauge wire which is lying around from a previous
job, but run two hot lines and two ground lines in parallel, as
diagrammed below.
Box: Hot ====================
* * * * * * * * * * * * * * * * * * * * * * * * * * * * Load Outlet
Box: Ground==================
So we have two black 14g wires running from the hot connector on the
breaker to the outlet and two white 14g wires running back from the
outlet to the ground in the box. Two questions:
1. What gauge single wire would this be equivalent to in current
carrying capacity? That is, would this be the same as running a single
10g or 8g or what? Maybe 14g / 2 = 7g?
2. This seems to be very unsafe but I'm not sure why. It's probably
against every wiring code everywhere. What's the danger with this set
up?
Again, I'm not going to do this, I'm actually going to go out and buy
the proper gauge wire for my project, but this popped into my head and
I wondered what the rest of you thought about it.
Paul
Hi,
Since you mention theory, if you make the length of wires EXACTLY same
to even the load current and make sure two wires always stay connected
TOGETHER, it'll be OK.

In theory, whether the wires are exactly the same length or not
matters not a wit.

"Theoretically" - it depends on what the breaker size is. If it is 30A
(which the wires would support) they have to be the same length (or else
the current is not split evenly between the wires). On a 15A breaker
"theoretically" it doesn't matter. The OP seems to be asking the first
question.

For paralleling under the NEC, not only do the lengths have to be equal,
you have to match conductor material, conductor area, insulation and
termination.

As Doug said, the NEC allows paralleling for wires over 1/0. Why would
you want to parallel small wires. You are increasing the probability of
a problem, including what someone might do in the future. And the
"right" size wire is about always easier to use.

As I believe someone said, wires have to (generally) be protected at the
source for the wire ampacity. A #14 (or 2-#14s) connected to a 30A
breaker is a violation.

I have read that ring circuits in the UK were used in the rebuilding
after WW2 because they used less scarce copper. If the ring circuit was
30A, the wire would be lighter than a 30A rating, but I believe it was
significantly higher than 15A. Since each side of the ring would seldom
be equal length, the current does not divide equally in each direction.
You also don't want "sockets" near the ends of the ring.

--
bud--- Hide quoted text -

- Show quoted text -

The wire used in the ring is rated at 20amp. I can't compare it with
your "guages" because we gave up using wire guages even before I was
an apprentice. We then use an imperial system but that has been
abandoned too , we have now gone metric.
You can put the sockets anywhere you like on the circuit. In practice
there are no problems. Remember it's all subject to a floor area
limitation of 100m2