Dangers of ring final circuit

[Baker1988]

Hi i have been set some home work from college to find out why ring final circuits are dangerous. I know the obvious that if one leg on the ring breaks it will not be a full ring and the 32 amp mcb will be too big for the cable as it will only be able to carry about 20 amps with out it been a ring which would over load the cable. But i can not find any thing other then what i already new can any one help me with this

 

[Amp David]

They're not dangerous. Whoever has asked you to prove this want shooting lol

 

[Baker1988]

Hi amp david it was my tutor at college that is what he set for home work he said they are dangerious and asked us to find out why i did not think they was dangerious as if they was why would we use them in this country where health and safety is a big part of every thing we do

 

[Guest123]

They are only dangerous to the uneducated buffoons that dont know any better.

Your "tutor" should know better!!!

 

[Baker1988]

But how does been uneducated make a ring dangerous? And also he may be doing it as a trick or something to try and get us to learn more about ring final circuits

 

[johnboy6083]

the question should of been to find the advantages and disadvantages of a ring final circuit. The question your tutor has set is very leading, and hes tryinmg to force his opinion on you.

IMO education should be about giving you the hard facts, and knowledege for you to make your own decsions.

 

[Guest123]

And also he may be doing it as a trick or something to try and get us to learn more about ring final circuits

I can only hope this is the case.

As you've said, the biggest risk would be if the 2.5/1.5 RFC were to 'break' and thereby become 2 radial circuits, each protected by a 32A OCPD which as we know would be above the CCC of the cable.

 

[Des 56]

Go back to your tutor and tell him they are not exlcusive as far as danger is concerned

A ring final has the potential for danger, as do all incorrectly operating circuits and just about everything else in the electrical industry

Find some reasons why, when the design of a ring is abused, where problems can arise
Present them as potential problems for a circuit described as a ring, but not installed or operating as such

 

[Baker1988]

Yes i already know the advantages and disadvantages as i have been looking this up for the past few days and have learnt loads of stuff about rfc but could not find anything about dangers So is my tutor wrong? are they not dangerious? Is this his personal appinion

 

[Baker1988]

Ok i will talk to my tutor thanks for all your help guys

 

[johnboy6083]

Yes it is. A cable is dangerous if its damaged, but we still dont label them as such. Any circuit installed incorrectly can become dangerous.The one thing all circuits ahve in common is that one of three things are required for them to become dangerous.

Intervention
damage,
or natural degradation

 

[Guest123]

Ok i will talk to my tutor thanks for all your help guys

Point him in my direction if he fancies a chat about them.

 

[Engineer54]

Hi amp david it was my tutor at college that is what he set for home work he said they are dangerious and asked us to find out why i did not think they was dangerious as if they was why would we use them in this country where health and safety is a big part of every thing we do

The only thing ''Dangerous'' here is Yet another numpty so-called lecturer that's perpetuating his ''OWN'' personal misguided views and prejudices onto his students. All this does, is burden these students with the myths and scaremongery we see all the time, in newly trained or trainee's in the posts they write .... I suppose this same lecturer tells you that you can't use the armour of SWA cable as your CPC too, or you Can't extend a PME earthing system from the house to a garage or shed....

And we wonder why these students are leaving collage/training centre's, with little or no idea of circuit design. Makes you wonder if it's these lecturers that are in dire need annual assessment, on their competency to teach, ...Just like the majority of the Part Pee electricians that were taught by these numbties....

 

[brman]

so are you saying that the original point made by baker1988 is not correct?
ie. a break in the ring will not be detected by the user so the ring could be operating beyond the cable capability. In this respect it could be considered more dangerous than a radial could it not?

Just trying to understand the situation myself....

 

[Guest123]

so are you saying that the original point made by baker1988 is not correct?
ie. a break in the ring will not be detected by the user so the ring could be operating beyond the cable capability. In this respect it could be considered more dangerous than a radial could it not?

Just trying to understand the situation myself....

As I said in post #7, that is the biggest risk of an RFC, as the householder would not be aware of it so the cable may if heavily loaded, be operating outside of it's capacity.

 

[johnboy6083]

what would cause a break in the ring, other than manual intervention? Maybe rodent damage, or drilling though a cable, but that would cause short circuit, which would operate the potective device.

 

[needasparks]

I totally agree with you E54,
Ive lost count the amount of times i have been on the phone to my son's college about the poor teaching and wrong information they are pumping out, the best one was that asbestos does not exist in any type of switchgear and i should know as ive been on the tools for 15 yrs, believe it or not this was from a H&S lesson.

 

[Guest123]

what would cause a break in the ring, other than manual intervention? Maybe rodent damage, or drilling though a cable, but that would cause short circuit, which would operate the potective device.

Number 3 on your list John.

Although a million to one shot, conductors becoming loose at their terminals over time 'could' cause a situation as described which may go unnoticed for a good length of time.

Highly improbable for both L&N to work loose but........

 

[Sparky Ninja]

I think you guys are taking this a little too serious.

I've asked similar a question to my students before, not necessarily that rings are dangerous, but more about there opinion to the potential dangers a ring final can create when under the control of "ordinary persons".

and the answer is YES. Ring final circuits are more dangerous.

 

[johnboy6083]

Number 3 on your list John.

Although a million to one shot, conductors becoming loose at their terminals over time 'could' cause a situation as described which may go unnoticed for a good length of time.

Highly improbable for both L&N to work loose but........

fair point lenny. is this more dangerous than any terminal working loose though, lets face it either a loose live, or neutral will probably cause a fire or burning on any circuit, long before it works completely loose.