Ring Mains or Ring Circuits

[iwire]

Re: Ring Mains or Ring Circuits

Originally posted by britt:
Iwire it is my understanding that the cord caps and some receptacles are fused to protect the lamp and appliance cords which we don't do since the Code allows 16AWG to be protected on a 20A ckt.

Yes exactly, I pointed out about the fuses as most of us would wonder about 30 or 32 amps at the outlet heading into the lamp cord.

 

[roger]

Re: Ring Mains or Ring Circuits

Roger, parallel would have to be the same direction from point to point. Two paths heading at 180 deg from each other to get back to where they started (source) in a 360 orb (circuit) can see very different obstacles.(impedances) I just can't consider a loop or a ring as parallel.

BTW, seems weird starting my post with "Roger"

Roger

 

[iwire]

Re: Ring Mains or Ring Circuits

Originally posted by roger:
BTW, seems weird starting my post with "Roger"

 

[roger]

Re: Ring Mains or Ring Circuits

Bob, LOL How did you know I do that?

Roger

 

[hurk27]

Re: Ring Mains or Ring Circuits

This is like dejavu or what?
Didn't we have this descussion with Paul in the old forum?

Roger roger over and out LOL

 

[roger]

Re: Ring Mains or Ring Circuits

Hey Wayne, I guess we're busted again.

Roger

 

[hurk27]

Re: Ring Mains or Ring Circuits

Yep

 

[dereckbc]

Re: Ring Mains or Ring Circuits

Well, do we have a consensus yet? Is it parallel or not? That is what I thought!

 

[karl riley]

Re: Ring Mains or Ring Circuits

Dereck, it is OK to go round and round on this because it is a ring...

Whether conductors describe a physical oval or run next to each other is electrically meaningless, so parallel can mean arranged in a loop.

Dereck, the overheating would be solved by using #12 instead of #14, but the whole point of introducing this circuit into the UK was economy, so they could use #14 for the whole ring. As of now overheating does occur when there is a break.

If you want to restrict the word "parallel" to refer to the case of a simple single circuit, that's OK with me. Is it in the NEC? Reference?

But I am interested in the electrical fact that the neutral return current from any load splits and returns on two different paths. It is joined at the outlet and joined at the neutral bus. Same with the hot. Current travels on two paths to reach the load. Break a neutral anywhere but in the very center of the ring and you will have net current in both directions. Neutral and hot current will not be equal, and a net current magnetic field is established. Same with a break in the hot. And the break will not be detected until the overheating is traced.

I concur with the UK moderator, Pauluk, that it was a bad idea.

So that's as far as I want to go round and round for tonight!

Karl

 

[don_resqcapt19]

Re: Ring Mains or Ring Circuits

The conductors of a ring circuit do not meet the definition for parallel conductors in 310.4.

electrically joined at both ends to form a single conductor

Don

 

[Guest]

Re: Ring Mains or Ring Circuits

I believe they are electrically joined at both ends to form a conductor. They are joined at the circuit breaker end, and they are joined in the "middle" of the ring.

The circuit is not serial, so it must be parallel.

I'll draw a picture later if it would help.

 

[tonyi]

Re: Ring Mains or Ring Circuits

Were they trying to save wire or breakers?

You could just split the ring somewhere near its geographic middle, put each end on a 15A fuse/breaker, and have 50% more net load capacity than with both ends on a single 20A - and eliminate any overheating issues on a break.

 

[roger]

Re: Ring Mains or Ring Circuits

Tony the UK method uses 16 amp wire and a 32 amp OCPD, so where would a break in the middle with two 16 amp breakers increase the caoacity.

Awwt, what? I think Ed already posted a drawing and most here have a good understanding of the discussion, you aren't going to start the surge suppression stuff again are you?

Roger

[ November 25, 2003, 10:51 PM: Message edited by: roger ]

 

[Guest]

Re: Ring Mains or Ring Circuits

Exqueeze me?

 

[iwire]

Re: Ring Mains or Ring Circuits

Originally posted by don_resqcapt19:
The conductors of a ring circuit do not meet the definition for parallel conductors in 310.4.

I agree that a ring circuit does not meet this NEC definition.

IMO that is a problem with the definition.

I think Karl's reasons for not wiring circuits in this manner are good ones.

Oh and Karl

Dereck, it is OK to go round and round on this because it is a ring...

LOL

[ November 26, 2003, 06:42 AM: Message edited by: iwire ]

 

[don_resqcapt19]

Re: Ring Mains or Ring Circuits

Wayne,

I believe they are electrically joined at both ends to form a conductor. They are joined at the circuit breaker end, and they are joined in the "middle" of the ring.

I would agree only if there was a single outlet on the ring circuit. if there is more that one outlet, the ring conductors are not joined at the ends. One supply conductor stops at one outlet and the other supply conductor stops at a different outlet. Yes, the circuit itself is a parallel circuit, but the conductors are not connected in parallel.
Don

 

[tonyi]

Re: Ring Mains or Ring Circuits

Originally posted by roger:
Tony the UK method uses 16 amp wire and a 32 amp OCPD, so where would a break in the middle with two 16 amp breakers increase the caoacity.

Oh, I see now - they really overload the heck out of it. A split and two 15's would certainly be safer and a pretty easy retrofit though.

 

[Guest]

Re: Ring Mains or Ring Circuits

Not to be argumentative, but I still don't see the ring circuit conductors stopping anywhere (unless there is a break in the ring). Using the drag strip analogy, it's like a drag strip where the two lanes start at the same point. In a ring circuit the lanes are not side-by-side. Their routes are different. The routes don't end at any one device. To me a ring circuit is more akin to parallel conductors run in separate wireways. Very separate, but still parallel. I see the ring circuit as acting like the plenum in a forced air heating system; or like the manifold in a radiant heating system. It's an interesting puzzle. The UK implementation appears flawed.

 

[karl riley]

Re: Ring Mains or Ring Circuits

Don, I don't mind hanging in there a little longer if we can see each other's points.

310.4 defines a parallel conductor at the end of the first paragraph:"....connected in parallel (elctrically joined at both ends to form a single conductor)."

Note it says electrically joined. One end is at the outlet. The other end is at the neutral bus. (or for the hots, at the same breaker). They don't have to lie physically parallel (a point of confusion?) The fact that the wire itself may not be physically continuous as it goes from outlet to outlet around the ring has nothing to do with the definition, since it is electrically continuous.

So a ring circuit involves paralleled conductors (2) from each outlet to the neutral bus or breaker. There are multiple paralleled circuits.

Perhaps the reluctance to call these conductors paralleled springs from the description of the only allowable configuration for paralleled conductors, as described in 310.4. They need to be the same length, etc, etc. But that is not the definition of paralleled; it's just the only correct way to wire paralleled conductors to meet NEC.

That's about all I can say, since we don't use these circuits in the US, and I think this is why.

Karl

 

[don_resqcapt19]

Re: Ring Mains or Ring Circuits

Karl,
I see your point, but I just look at it a different way. Wire A goes from the breaker to outlet A, wire B goes from outlet A to outlet B, and wire C goes from outlet B to the breaker. Wire A is not joined at both ends with wire C so they are not conductors in parallel.
I do agree that there may be excessive EMF produced by this type of circuit because of the multiple current paths and the circuit would not be a good idea from that standpoint. I just don't agree that 310.4 prohibits the use of ring circuits.
Don