Worth converting 2 radial circuits to ring?

[mobilejake]

Hi,
I just had an electrician in to install a new CU in my flat.

In the course of his testing/installation he discovered that rather than a single ring feeding all sockets, there were 2 radials. One served 9 sockets and the other served 3 sockets.

He said in future I might want to consider laying a new wire for a single ring circuit serving all the sockets to clean it up.

My questions are - is this necessary (regulations wise)? Is it worth doing (advantages/cost)? and finally would it be better just to convert the two radial circuits to 2 rings?

Cheers,
J

 

[JohnW2]

In the course of his testing/installation he discovered that rather than a single ring feeding all sockets, there were 2 radials. One served 9 sockets and the other served 3 sockets. ... He said in future I might want to consider laying a new wire for a single ring circuit serving all the sockets to clean it up. ... My questions are - is this necessary (regulations wise)? Is it worth doing (advantages/cost)? and finally would it be better just to convert the two radial circuits to 2 rings?

Certainly not necessary, regulations-wise. There are pros and cons of rings and radials, and some actually favour radials.

Your present arrangement sounds a bit 'lop-sided' (9 sockets on one radial and 3 on the other), so there might be scope for a bit of useful 're-arrangement', even if you kept the two radials.

What rating of breaker (MCB) or fuse does each of these radial circuits have? Are some of the sockets in a kitchen or utility room (serving washing machines, dryers, dishwashers etc.)? Do you happen to know what size cable is used for the radial circuits?

Kind Regards, John

 

[ekmdgrf]

Unless you have a need to (read you keep tripping the circuits by drawing too much current) it sounds like a waste of time and money to create a ring.

 

[mobilejake]

Thanks

The cable is 2.5mm. The reason for the lopsidedness is because the extra radial serves an old extension..

There is a clothes washer and dryer but no dishwasher on the circuit. The cooker is all gas too!

If its fine with regs and no significant advantages, then i think i will leave well alone - unless i run out of juice...

 

[JohnW2]

The cable is 2.5mm. The reason for the lopsidedness is because the extra radial serves an old extension.. There is a clothes washer and dryer but no dishwasher on the circuit. The cooker is all gas too! If its fine with regs and no significant advantages, then i think i will leave well alone - unless i run out of juice...

Do I take it that each of the radials has a 20A MCB or fuse?

Are both the washing machine and dryer on the same radial? If so, in theory a 20A radial might not theoretically be adequate for powering both of them simultaneously, particularly during some parts of the washer's cycle. I said that there were pros and cons of rings/radials, and that is one of the downsides of (20A) radials. If they were converted to a 30/32A ring, then that potential issue would obviously go away.

Kind Regards, John

 

[ekmdgrf]

Although that in itself opens another can of worms. One has to be mindful of balancing the ring with those two loads, which I hazard are situated right next to each other. On the other hand, depending on your washing habits/family size, it might be highly unlikely to have both appliances running at the same time. I understand that washing and drying clothes is a serial, rather than parallel process. Another way to address the problem, instead of investing in 20m of twin and earth is to invest in 20m of washing line.

Incidentally, upon decorating the kitchen recently, I discovered the worlds smallest RFC. A double socket on it's own RFC marked "washer/dryer".

 

[JohnW2]

Although that in itself opens another can of worms. One has to be mindful of balancing the ring with those two loads, which I hazard are situated right next to each other.

True, in theory. However, in practice, even if the cable were de-rated to a CCC of 20A (the lowest CCC allowed for a RFC) the two 'right next to each other' sockets would have to be very close to one end of the ring to overload the cable. Indeed, if the cable were 'clipped direct', it would be impossible for a 2 x 13A load to overload the cable, no matter how close they were to to one end of the ring.

Incidentally, upon decorating the kitchen recently, I discovered the worlds smallest RFC. A double socket on it's own RFC marked "washer/dryer".

If I understand you correctly, that sounds rather like a 5mm² radial to me!

Kind Regards, John

 

[EFLImpudence]

I will never understand why RFC stands for Ring Final Circuit but not Radial Final Circuit.

In view of the number of confusing details in the regulations which we frequently decry, this must be the most inexplicable.

 

[JohnW2]

I will never understand why RFC stands for Ring Final Circuit but not Radial Final Circuit.

Quite so. I do try to avoid using 'RFC' for that very reason (particularly in discussions about both radial and ring circuits), but I do sometimes 'fall into the trap'.

In view of the number of confusing details in the regulations which we frequently decry, this must be the most inexplicable.

For once, I'm not at all sure that you can blame the regs (i.e. I'm not sure you'll find "RFC" in the regs) - I think this particular diabolical ambiguity is probably down to electricians

Kind Regards, John

 

[ekmdgrf]

I will never understand why RFC stands for Ring Final Circuit but not Radial Final Circuit.

As a master of pedantry and nit-picking, I'm ashamed to say that that ambiguity had passed me by quite unnoticed.

 

[JohnW2]

As a master of pedantry and nit-picking, I'm ashamed to say that that ambiguity had passed me by quite unnoticed.

It's often been commented on here, and elsewhere, but the one (of the two, or more, possible) meanings of "RFC" seems to be so ingrained in many/most electricians' vocabularies that I think it's become an essentially irreversible situation!

Kind Regards, John

 

[mobilejake]

Ok - it seems after much investigation there were not 2 radials but 1 ring. A combination of the electricians low battery on his tester and a couple of "burnt" sockets.

I don't quite understand.

But I am told it is a 2.5mm cable ring circuit - now on a new consumer unit!

 

[ekmdgrf]

When you break a ring, you get two radials. The slight downside of this is that if one of the radials draws all 32A available to it, your house might burn down. Many people consider this to be a bad thing.

 

[JohnW2]

When you break a ring, you get two radials. The slight downside of this is that if one of the radials draws all 32A available to it, your house might burn down. Many people consider this to be a bad thing.

I suppose I can't knock you for saying that, since its a sort-of 'party line', but do you seriously believe that, in reality, 32A flowing through a cable which would quite probably have a CCC of 27A would produce any noticeable problems at all, let alone a fire?

Do I take it that you are one of those who is 'anti ring'?

Kind Regards, John

 

[mobilejake]

I'd be one of those that thinks their house burning down is a bad thing..

The question now is - do i need to be concerned those sockets burned out? Will the new RCD CU prevent that happening?

Am I better off converting to radials (to turn the whole post a full 180 degrees)