Ring circuits from another thread

[karl riley]

Re: Ring circuits from another thread

Roger, getting back to the diagram, you have a load on one hot but the neutral splits and goes back on both parts of the loop, hence net current exists on both cables. Net currents induce currents and heat in the conduit. This is the reason for 300-3(b) and I believe 310-4. I think I'm repeating myself.

If both cables run together the net current field would not show up much, since it would simply be paralleled hots and paralleled neutrals. But I thought the ring circuits made a ring path in order to use the least conductor length. Is there something I'm missing here?

Karl

 

[jrdsg]

Re: Ring circuits from another thread

sorry for what is probably a non-sequitor on this thread, but there is a similar fire alarm circuit that is configured in a ring for redundancy. i thought it might be a good reminder for readers of this thread to review their fire panel wiring diagrams. i won't say anything more so as to leave the research to those that are curious.

 

[karl riley]

Re: Ring circuits from another thread

Redundancy makes sense for emergency alarm systems which do not carry a constant load.

Karl

 

[roger]

Re: Ring circuits from another thread

Karl, as with a fault in any wiring method net currents can be a condition of the fault.

jrdsg, a class A loop as you said is for redundancy and even though redundancy is a side plus for the ring circuit it is not the main reason.

Anyways, for clarification, I have and do use this in LV situations. I can see both pro and con in 120v and up, although I haven't ever done this.

For an experts (Paul Coxwell A.K.A. Pauluk) comments on this go here, here , and here

Roger

 

[karl riley]

Re: Ring circuits from another thread

Roger, thanks for those three links where a British electrician discusses the ring circuits. A lively interchange with the Americans. Great stuff.

I was interested to see that the Brit feels that the ring circuit should be abandoned. The disadvantages are that the conductors are too small for the potential loads that can occur, there can be breaks in both the hot and neutral without anyone knowing about it while producing overloaded conductors, and the magnetic fields from unbalanced net currents can be large (though that aspect was touched on lightly).

The reasons for the ring circuit design were shortage of materials in the 40s, since ring circuits use less material and you can get away with smaller conductors for average loads as long as no breaks occur in the wrong places. They were also probably easier to wire in the brick buildings which make up the majority of houses there.

Great threads, which I recommend to anyone else here who wants to hear it thoroughly thrashed out between a polite Brit and an aggressive American.

Karl

 

[roger]

Re: Ring circuits from another thread

Karl you're welcome and FWIW Paul has my upmost respect for his diplomacy and electrical expertise. (like yourself )

Roger

 

[karl riley]

Re: Ring circuits from another thread

I saw a diagram of the NE power grid in the Times today. Darned if it wasn't a ring circuit!

Karl