UK wiring style

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PetrosA said:
So maybe my assumption is wrong. If not for redundancy, why would you run a circuit according to exception 1?

My understanding of the exception is that if you run smaller than 1/0 in parallel, it must meet those conditions. How does that allow you to run smaller than 1/0 if it doesn't meet those exceptions? If you read it to mean that running parallel conductors under 1/0 in general is allowed, but if they feed those items mentioned in exception 1 they must meet those requirements, doesn't that become a design specification, which the NEC isn't supposed to be?

Personally, I don't see anything wrong with a ring circuit in theory. The problem I see is that it's not a wiring style that electricians here would easily identify in use if they came across it in the field. The term "branch circuit" is a visually descriptive name based on the wiring model we use (a tree) and a ring circuit doesn't fit in that model. For instance, in a ring model you wouldn't be allowed to branch out from the ring. Instead, you would have to expand the ring by running two cables from the tap point to the next device and back. Ultimately I think the best argument against using ring circuits in the US is that it would violate 110.8 (only suitable wiring methods are mentioned) and potentially 110.12 (workmanlike manner). Ring circuits are NOT mentioned in the NEC, so are therefore not suitable, and installing one would be unworkmanlike because you'd be violating 110.8.
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The problem is the language employed in the exception, the phrase "shall be permitted to be run" does not mean they must be run. To make the installation method mandatory for all sizes under 1/0, it should read "shall be run". The phrase "shall be permitted" doesn't make the action it refers to mandatory and implies that this method must be allowed and also other methods may exist which may or may not be permitted. Words have meaning, and the Technical Committe should know better.
 
Parallel is parallel, ring is ring, and never the twain shall meet.

Our NEC doesn't address 'ring' circuits, simply because it has not been our practice to use them - at least, on our side of the meter. Our PoCo's use them all the time, expecially in tract developments, where the transformers are often in a 'ring' circuit.

"Ring" circuits, like their plumbing equivalent the 'loop,' are a bit of a cipher. That they work is clear. That they provide a more reliable supply to the device is open to discussion. Mathematically, your 'voltage drop' calculations (as well as any other math) doesn't work, because the 'ring' results in an undefined value.

Meanwhile, back to the job site: You need to simply tell the guy we don't do things that way. There are a number of other differences as well. Sure, England is a modern country with a wonderful pool of talented electricians - but if they want to work here, they need to do things our way.

In that regard it's no different than back-stabbing devices: some shops love in, others hate it ... but the boss gets to make the call.
 
renosteinke said:
"Ring" circuits, like their plumbing equivalent the 'loop,' are a bit of a cipher. That they work is clear. That they provide a more reliable supply to the device is open to discussion. Mathematically, your 'voltage drop' calculations (as well as any other math) doesn't work, because the 'ring' results in an undefined value.
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Not sure I agree with that. The live and neutral, being within the same sheaths are the same conductor lengths and you can calculate the impedance of each section of the ring and how any particular load or loads will draw current from either end. A tedious application of Kirchhoff's circuit, particularly if there are a lot of loads, but not indeterminate.
I also don't agree with the Electromagnetic interference comment in the Wikipedia.article.

http://en.wikipedia.org/wiki/Ring_circuit

The live and neutral conductors are the same length for any particular section of the circuit. If you draw out a simple circuit with say just one or two loads and represent the conductors as resistances of equal value for the live and neutral of each section the currents balance.

renosteinke said:
There are a number of other differences as well. Sure, England is a modern country with a wonderful pool of talented electricians
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Scotland and NI have talented electricians too.........I'll assume you meant UK.......:thumbsup:
Yes, there are quite a few differences, no split phase, no steel conduit, no wire nuts, no back stabs, a simpler to understand (IMO) way of specifying conductor sizes. A 16mm^2 conductor is 16mm^2 - that's its cross-sectional area. It is exactly what it says on the box to paraphrase a popular television commercial here...... it's usually (maybe always marked) marked on the cable. And, the bigger the number, the bigger the cable. How simple is that.:cool:

renosteinke said:
but if they want to work here, they need to do things our way.
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No disagreement with that. But maybe one day you guys will catch up with us..........:p
 
If I was an inspector I would fail a ring circuit based on the parallel conductor sections of the NEC.

We can fight all day if it is or isn't a parallel circuit as the NEC is not clear about it, that being the case it is up to the local AHJ / inspector to make the interpretation.
 
The only reason I would even consider a ring circuit would be for voltage drop.

For redundancy or back up it would give you a sense of false security.
One feed might be loose for years before anyone would notice and may be never.


Disadvantage or drawback.

Chances of this ever happening would be very slim.

If you where to loose your hot on one circuit and your neutral on the other
or vise versa on your feeders, you would loose your inductive canceling
effect of the circuit.

If this circuit where loaded to the gills with say a coffee maker and a
freezer this would be a very dangerous situation.

This would make the 310. rule for all the conductors of the same circuit
to be bundled together even more important in this case.



Ronald :)
 
renosteinke said:
Our NEC doesn't address 'ring' circuits, simply because it has not been our practice to use them - at least, on our side of the meter. Our PoCo's use them all the time, expecially in tract developments, where the transformers are often in a 'ring' circuit.
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Also, IIRC the ETSA rules for film set/production power distribution spends a lot of space describing practices for ring-wired feeders. Unfortunately I can't find my copy right now. Granted that's not the same as branch circuits.
 
ronaldrc said:
If this circuit where loaded to the gills with say a coffee maker and a
freezer this would be a very dangerous situation.
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Really? So all that knob and tube wiring is blowing up houses left and right due to inductive ramifications? :lol:

You guys are really grasping at straws. Everyone keeps saying its parallel conductors, but not a single person has explained how it can be parallel conductors. Do any two wires share the same termination points at both ends? If not, then they are not parallel.

Moreover, if that application of parallel conductors were applicable, then why is it not applicable when you wirenut several neutrals (current carrying conductors) together in a junction box? You don't hear anyone worrying about that.
 
ronaldrc said:
The only reason I would even consider a ring circuit would be for voltage drop.
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Hello Ronald, I actually do use ring circuits on LV lighting circuits for VD.


Now, let's take this a step further and say we land the ends of the ring circuit on two separate 20 amp breakers, this way we can supply a 40 amp load with # 12 conductors.
;)


Roger
 
roger said:
Hello Ronald, I actually do use ring circuits on LV lighting circuits for VD.


Now, let's take this a step further and say we land the ends of the ring circuit on two separate 20 amp breakers, this way we can supply a 40 amp load with # 12 conductors.
;)


Roger
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Hey Roger, Great idea,I'd do it in a heart beat. I guess its a good thing I'm retired.:roll:
 
roger said:
Hello Ronald, I actually do use ring circuits on LV lighting circuits for VD.


Now, let's take this a step further and say we land the ends of the ring circuit on two separate 20 amp breakers, this way we can supply a 40 amp load with # 12 conductors.
;)


Roger
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I did a re-mod that had the receptacles wired that way by mistake. When all the receptacles got replaced, you could turn off a breaker and it would still be hot, as it was being backfed from the other breaker. We didn't notice it right away as most of the work was done with no power to the house. We didn't do the initial wiring. We inhereted the job when the inspector found out it was being done with no permit or license, etc.
 
ronaldrc said:
... Point taken, and really can't say I disagree, but Nec sure doesn't like it. ...
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Hummmm .... don't know about that. Maybe it's several people on this forum reading the NEC don't like it.

Could be the NEC doesn't care one way or the other.

Would this be a preceived code violation if the circuit was #1, 13.8kv ring out to several transformers? Don't get caught up in if this is utility. This is a known, somewhat uncommon, industrial design.

ice
 
iceworm said:
Would this be a preceived code violation if the circuit was #1, 13.8kv ring out to several transformers? Don't get caught up in if this is utility. This is a known, somewhat uncommon, industrial design.

ice
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As careless as I am I wouldn't last a day working on utility lines, if they had a back feeds
maybe a half a day. :lol:

Ronald:)
 
roger said:
Now, let's take this a step further and say we land the ends of the ring circuit on two separate 20 amp breakers, this way we can supply a 40 amp load with # 12 conductors.
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But we don't say that.
A final ring main is fed from one source, one supply, one breaker or fused supply.
 
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K8MHZ said:
I did a re-mod that had the receptacles wired that way by mistake. When all the receptacles got replaced, you could turn off a breaker and it would still be hot, as it was being backfed from the other breaker.
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With a ring main there isn't another breaker. That's the whole concept.
 
iceworm said:
...

Would this be a preceived code violation if the circuit was #1, 13.8kv ring out to several transformers? Don't get caught up in if this is utility. This is a known, somewhat uncommon, industrial design.

ice
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Typical primary loops go through switches in the transformers. Any transformer or loop section can be de-energized using the switches in the adjacent transformers.

It is a parallel wiring method, but not considered parallel conductors because of the switching.
 
Besoeker said:
But we don't say that.
A final ring main is fed from one source, one supply, one breaker or fused supply.
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I know that, I was just adding food for thought.

If I'm not mistaken your regs prohibit paralleling OCPD's the same as the NEC does.


Roger.
 
I'm still not understanding how a ring circuit wouldn't violate 110.8. There's no mention of a ring circuit anywhere in the NEC, hence it's not an acceptable wiring method. We use branch circuits, not ring circuits.
 
PetrosA said:
I'm still not understanding how a ring circuit wouldn't violate 110.8. There's no mention of a ring circuit anywhere in the NEC, hence it's not an acceptable wiring method. We use branch circuits, not ring circuits.
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The NEC is also silent about whether the ground prong should be up or down. So does that mean they can be neither, and all of your outlets have to be mounted sideways? :lol:


110.8 is about the most bogus statement in the whole NEC. "Recognized" by whom? It doesn't even state who, how, or where a method is recognized and how it is determined whether or not something is recognized or not.
 
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