"Closed loop circuit"

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bphgravity

Senior Member
Location
Florida
I have been readng a 1911 ICS electric wiring book that shows various methods of running circuits. One method is called the "closed loop circuit" where the ungrounded and grounded conductors feed from the source to the loads and then back to the source. It even has a drawing showing this. It does not describe the purpose or benefit of this method. This is certainly not a common practice of today. It seems to have potential hazards, so I can't think of a good reason to do this.

[ March 12, 2003, 11:34 PM: Message edited by: bphgravity ]
 

charlie

Senior Member
Location
Indianapolis
Re: "Closed loop circuit"

I believe (I have no basis in fact and my memory is fuzzy on this issue) the purpose is to allow a circuit to run cooler and to be loaded heavier. On the surface, it sound pretty good but imagine a 20 ampere kitchen circuit that is closed loop. Now put a duplex receptacle on that circuit and load each to its maximum. Since you are pulling from two circuit breakers (fuses in 1911) you can actual pull 40 amperes through a 15 ampere receptacle . . . HMMM . . . good idea . . . NOT!
 

Ed MacLaren

Senior Member
Re: "Closed loop circuit"

I would guess it was used in the early days for continuity of service, and is probably not legal today because of "conductors in parallel" rules.



ED
 

iwire

Moderator
Staff member
Location
Massachusetts
Re: "Closed loop circuit"

Thanks Ed, great illustrations as always.

I see it begins and ends on the same OCPD so it will not get "double" amperage just redundancy and less voltage drop.
 

dereckbc

Moderator
Staff member
Location
Plano, TX
Re: "Closed loop circuit"

I remember this being discussed a couple of months ago under the heading of a ?Limy Circuit?. The real name as Bob mentioned is a ?Ring Circuit?. The ring circuit is used in the UK for lighting. It is similar to a parallel conductor circuit, but it is not.

UK as mentioned, uses it for lighting. They use it on a 30 amp circuit @ 230 VAC. It has the advantage of being able to supply all the lighting for a dwelling by only using one circuit with very little voltage drop anywhere along the length as it forms a loop instead of a parallel circuit. If you looked at Ed?s drawing you will see the loop. Another advantage if the circuit is broken, it will continue to work, with little or no danger.

As far as can it be used here in the US? Beats me. The only problem I can see with the circuit is if used with non-linear loads it would get rather noisy, but if used for lighting as the Brits do, who cares.

For those interested in reading some more from the UK go to http://www.diynot.com/pages/el/el011.php
 

jsinclair

Member
Location
Pennsylvania
Re: "Closed loop circuit"

I thought I was crazy when I came across this wiring method here in the states. Imagine a panel changeout and flipping on the new breakers to discover that you have phased 4 circuits. Only to come to find that the 4 circuits were actually rings. Quite and interesting problem if you have never run into it before.
 
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