On Tue, 26 Jan 2010 18:04:44 -0500, Wes wrote:

jk wrote:


That has NOTHING to do with loop circuits. From the point of view of
loosing the neutral, the two wires of the loop, look JUST the same as
the one of the radial system. There is no difference.

What the loop does do is provide a more even impedance to a given
point in the circuit. The impedance reaches a peak at 1/2 way round
the circuit, and then starts dropping again.


My question had nothing to do with trying to eek out additional ampacity from a system as
the British do.

I scanned though my copy of the NEC and have not found the phrase that makes ring wiring,
staying in the normal rules for box fill, ampacity of conductors, ect illegal.

Is threre something like a branch circuit must be fed from one end only or something like
that? I'm just trying to imagine the language.


300.3Conductors.
....
(B)Conductors of the Same Circuit. All conductors of the same circuit
and, where used, the grounded conductor
and all equipment grounding conductors and bonding con-
ductors shall be contained within the same raceway, auxil-
iary gutter, cabletray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with
300.3(B)(1) through (B)(4).

(1)ParalleledInstallations. Conductors shall be permit-
ted to be run in parallel in accordance with the provisions
of 310.4 ...

......

310.4 Conductors in Parallel.
(A) General. Aluminum, copper-clad aluminum, or copper
conductors of size 1/0 AWG and larger, comprising each
phase, polarity, neutral, orgrounded circuit conductor shall
be permitted to be connected in parallel (electrically joined
at both ends).

I read that to mean you can run 1/0 and larger conductors in parallel
if they're run together. 12 ga romex daisy-chained around the
perimeter of a room with both ends tied to the breaker would be (1)
too small and (2) not "within the same raceway, auxiliary gutter,
cabletray, cablebus assembly, trench, cable, or cord."

--
Ned Simmons