Ring final circuit vs Radial final circuit

[Engineer54]

RING ISSUES AGAIN...I'm sure I've said this before but not on this thread...Anyway.I had to do some work in a house,moving a socket for the tv amp or something.My apprentice was at the consumer unit switching off,then back on again,the mcbs one at a time coz nothing was labled at the consumer unit. But the socket tester's neon indicators failed to extinguish. My apprentice was also leaving me in the dark as he was switching off 6amp mcbs too.So we swopped,me at the board end and him at the socket.I switched all the mcbs off except one 32amp and it was still live,then I flicked the last one off too and he yelled down to me that,that was it.So I flicked everything back on except that last mcb,only to find when I'd got back to the socket that it was live again(the hard way)...swearing profusly at my"thick" apprentice,I made my way back down to the cu and knocked the other 32amp mcb off and the first one back on again,then back up to the attic again,the attic socket(still live?) just had one cable at it...a spur off the house ring..It took a wee while before it sunk in that in order to isolate this circuit it was necessary to operate two breakers and later found out the same applied to the kitchen ring too.....The two ring legs had been interconnected,outgoing house ring leg connected to return leg from kitchen,at the mcb and return house ring connected to outgoing kitchen leg.It was impossable to switch off any socket via a single mcb. Ever since that I've gone off rings...Pity someone wouldn't enlighten the designers and engineers who do the drawings for us to follow, of the HAZZARDS of(improperly tested) ring circuits.

Why would they need to do that?? They are expecting the installation to be installed by competent qualified electricians, not by some knob who was stacking shelves a few weeks previously!!

 

[supertoad]

glad its not only me has had this problem! working on my own i use a "singing plugin tester"
agree with all your comments

 

[Engineer54]

glad its not only me has had this problem! working on my own i use a "singing plugin tester"
agree with all your comments

What and whose comments??

 

[kingeri]

RING ISSUES AGAIN...I'm sure I've said this before but not on this thread...Anyway.I had to do some work in a house,moving a socket for the tv amp or something.My apprentice was at the consumer unit switching off,then back on again,the mcbs one at a time coz nothing was labled at the consumer unit. But the socket tester's neon indicators failed to extinguish. My apprentice was also leaving me in the dark as he was switching off 6amp mcbs too.So we swopped,me at the board end and him at the socket.I switched all the mcbs off except one 32amp and it was still live,then I flicked the last one off too and he yelled down to me that,that was it.So I flicked everything back on except that last mcb,only to find when I'd got back to the socket that it was live again(the hard way)...swearing profusly at my"thick" apprentice,I made my way back down to the cu and knocked the other 32amp mcb off and the first one back on again,then back up to the attic again,the attic socket(still live?) just had one cable at it...a spur off the house ring..It took a wee while before it sunk in that in order to isolate this circuit it was necessary to operate two breakers and later found out the same applied to the kitchen ring too.....The two ring legs had been interconnected,outgoing house ring leg connected to return leg from kitchen,at the mcb and return house ring connected to outgoing kitchen leg.It was impossable to switch off any socket via a single mcb. Ever since that I've gone off rings...Pity someone wouldn't enlighten the designers and engineers who do the drawings for us to follow, of the HAZZARDS of(improperly tested) ring circuits.

I don't really get what you're saying. Because at some point some idiot has joined up two circuits, how is that a problem with ring circuits in general? Someone could just as easily join two radials, or two lighting circuits. If a ring is designed and installed properly then it is a very versatile and useful circuit. What happens years down the line when some fool messes with it isn't a refection on the circuit itself.

 

[candles]

I don't really get what you're saying. Because at some point some idiot has joined up two circuits, how is that a problem with ring circuits in general? Someone could just as easily join two radials, or two lighting circuits. If a ring is designed and installed properly then it is a very versatile and useful circuit. What happens years down the line when some fool messes with it isn't a refection on the circuit itself.

I have encountered this problem as well. Each leg of a ring main in a different mcb. Whoever wired the circuit made a mistake. At least with radial circuits this cannot happen.

 

[7029 dave]

Old thread.

 

[Knobhead]

Wonderful, you’ve resurrected a two year old thread to tell us absolutly nothing useful.

 

[Adam W]

It might be old but it's still relevant and one of those discussions that comes up time and again, like exporting an earth to an outbuilding.

 

[Knobhead]

Comes up now and again? It’s so repetitive even Epsom Salts won’t help it.

 

[driverman]

Re wrong connections like above...........been going for years..........With just the old 4 way Wylex fuse boxes, with 1 x cooker 1 x ring 1 x imm/htr 1 x light circuits, many electricians would connect one leg of the ring with the IMM/HTR circuit and the other leg of the ring would then be on its own 15amp fuse...........so nothing new! lol

 

[Pete999]

Hello mandinga,

the point of a ring final circuit is to use a particular size cable to carry more current than it would if it was a radial circuit. This idea apparentley came about after the 2nd world war. To save on copper wires.

Now the maximum amount of current a 2.5mm T&E is 24 amps. If we are using 2 cables to go to each point of that circuit, then in theory, you can pull twice as much current. Its actually a little less, thats why we use a 32a mcb for a 2.5mm ring circuit not a 40a or 45a. Remember we must always protect the cable from exceeding its current carying capacity.

So 20a mcb for a 2.5mm radial and 32a mcb for a 2.5mm mcb.

Also because the circuit is a ring, the resistance of that circuit is half that of a radial (in theory) and therefore providing a lower r1 + r2.

Hope that helps mate. Sorry, not too great at wording things I want to say.

R1+R2 not r1+r2

 

[Pete999]

I have done some research into this, and from distant memory, the english love of ring mains being able to supply 32A, is to enable us to use "two bar electric fires", just as our Gran had!

I am a strong beliver that the only area that needs 32A ring main is the kitchen / utility. I prefer to fit circuits for bedrooms etc as 16A radials. May need one or two more MCbs.

From memory, we are one of the only countries that still exist on using Ring mains.

Ring Final Circuit, not ring main

 

[driverman]

Ring Final Circuit, not ring main

I'm always guilty of that......old habits die hard.............ring main, ring circuit. been out of the game far too long. I suppose to be 100% correct all circuits are final circuits in a domestic situation.

 

[Pete999]

I'm always guilty of that......old habits die hard.............ring main, ring circuit. been out of the game far too long. I suppose to be 100% correct all circuits are final circuits in a domestic situation.

I'm just a pedantic old git

 

[driverman]

I'm just a pedantic old git

I would of never guessed that!

 

[Risteard]

I suppose to be 100% correct all circuits are final circuits in a domestic situation.

Except if they're not, i.e. distribution circuits.

 

[GMES]

I'm just a pedantic old git

We didn't need it confirming Pete :rofl:

 

[Pete999]

We didn't need it confirming Pete :rofl:

B----r me I 'm on the hit list today am I?:33:

 

[GMES]

B----r me I 'm on the hit list today am I?:33:

Never mate but I knew it would wake you up lol
Besides I am off to work shortly, so I wont be picking on you again till about 6pm!!

 

[Pete999]

Never mate but I knew it would wake you up lol
Besides I am off to work shortly, so I wont be picking on you again till about 6pm!!

Listem Mate with er indoors rattlin my senses all night I had to get up at 05:00 for some peace and quiet, jeez she can certainly put out some zzzzs when she wants to

 

[camerabloke]

I'm just a pedantic old git

No just a git

 

[Pete999]

No just a git

That's just not nice,

 

[telectrix]

at least he left out "old". :8:

 

[camerabloke]

Hahahaha

 

[Pete999]

Suppose that was decent of him, he's still a muppet

 

[camerabloke]

And your still a git

 

[Dan]

Just bumping some threads in the Electrical Wiring Theories and Regulations forum category here on our Electricians Forums. If this specific topic isn't current, just ignore it, it'll drop off the list in no time. However, if it's something you'd like to contribute to, feel free to reply and bring it back into current discussion.

 

[Patrick Powers]

Ring mains are much better for the environment. Radials are wasteful of copper and more besides.

 

[LastManOnline]

Ring mains are much better for the environment. Radials are wasteful of copper and more besides.

Where did you learn that?

 

[Mikegh]

I'm a big fan of the ring circuit in general but I would be in favour of outlawing the ring final circuit in domestic installations

Reason being that it's not a necessity and it would prevent hazardous situations such as breaks in the ring and overcurrent on spurs

 

[telectrix]

I'm a big fan of the ring circuit in general but I would be in favour of outlawing the ring final circuit in domestic installations

Reason being that it's not a necessity and it would prevent hazardous situations such as breaks in the ring and overcurrent on spurs

still useful in a kitchen though. where the load would require a 4.0mm radial.

 

[DPG]

I'm a big fan of the ring circuit in general but I would be in favour of outlawing the ring final circuit in domestic installations

Reason being that it's not a necessity and it would prevent hazardous situations such as breaks in the ring and overcurrent on spurs

But if you get a break in the CPC in a ring circuit, at least you still have a CPC present.

Pros and cons of both circuits really.

 

[littlespark]

We’ve had this same discussion on a much more recent thread. No point going over it all again.

 

[DPG]

We’ve had this same discussion on a much more recent thread. No point going over it all again.

Fair point.

 

[LastManOnline]

We’ve had this same discussion on a much more recent thread. No point going over it all again.

Agree. Although I find the "ring circuit better for the environment" argument interesting. Smacks of desperation to me.

 

[LastManOnline]

But if you get a break in the CPC in a ring circuit, at least you still have a CPC

Except that it will be undersized and go undetected until the next full inspection.

 

[DPG]

Except that it will be undersized and go undetected until the next full inspection.

Oh yes, it's far from ideal I realise that. But on a radial it would be non existent.

 

[LastManOnline]

still useful in a kitchen though. where the load would require a 4.0mm radial.

You have hit the jackpot there TEL. Run a 4mm radial instead of a ring circuit. Let's see... get rid of the two 2.5mm,s.Replace with a 4mm.Thats a, saving of 1mm of copper per circuit. Think of the benefits for "the environment" ?

 

[7029 dave]

4mm radial x2 =8mm= no saving ?

 

[Pretty Mouth]

Except that it will be undersized and go undetected until the next full inspection.

Probably wouldn't be undersized, from an adiabatic point of view, unless rewireable fuses. From a Zs POV, possibly, but not if RCD protected.

 

[Petej999]

Agree. Although I find the "ring circuit better for the environment" argument interesting. Smacks of desperation to me.

What do you mean by "smacks of desperation"

 

[LastManOnline]

What do you mean by "smacks of desperation"

Well when you offer an arguement for which system or accessory might be more advantageous over another, people usual put forward sound electrical reasons. Its only in connection with the ring circuit that I hear "environmental reasons" been put forward. That to me smacks of a poor defence for a wiring system that sadly (and through no fault of its own) is simply viewed worldwide (with a few exceptions) as inferior

 

[LastManOnline]

4mm radial x2 =8mm= no saving ?

I meant a single 4mm radial. But anyway, it was meant in jest?

 

[7029 dave]

I meant a single 4mm radial. But anyway, it was meant in jest?

I'm only mucking about meself , Lastman .