Have come across a 16A Ring Final

[vwes59]

I've not come across this before. The current regs state it should be on a 32A MCB. I've been asked to re-wire a bedroom which will involve extending this ring. It already serves two other bedrooms and the lounge. I know I probably should tell the client to upgrade this MCB to 32A, but is it necessary ? The ring is on 2.5mm T&E. It's a bit of an unusual find. The house was built in the 1930's but was rewired only recently, so I'm surprised to find such a situation.

Any thoughts ?

 

[Dustydazzler]

Seen loads of rings on a !6a or 20a mcb , especially on newer builds and new flats

I think some sparks do this for 2 reasons , 1 because of de-rating for insulation and 1 because they ran out of 32a devices

 

[Strima]

If it's an older property there may be a break in the ring and the OCPD has been downrated.

 

[littlespark]

Are you sure it’s a ring?
As above… maybe it was a ring but due to a fault it’s been turned into a two branch radial.

Don’t replace it with a 32 unless you know for sure…. And quite frankly, why would you need to? 16 will be sufficient for bedrooms.

 

[James]

Are you sure it’s a ring?
As above… maybe it was a ring but due to a fault it’s been turned into a two branch radial.

Don’t replace it with a 32 unless you know for sure…. And quite frankly, why would you need to? 16 will be sufficient for bedrooms.

Getting a bit tight if there are a couple of people who like to use hair driers etc at the same time, that is up to 16A on its own.

 

[littlespark]

Getting a bit tight if there are a couple of people who like to use hair driers etc at the same time, that is up to 16A on its own.

Sounds like you've got daughters as well. driers, straighteners, chargers, music on full blast.....

 

[Petej999]

I've not come across this before. The current regs state it should be on a 32A MCB. I've been asked to re-wire a bedroom which will involve extending this ring. It already serves two other bedrooms and the lounge. I know I probably should tell the client to upgrade this MCB to 32A, but is it necessary ? The ring is on 2.5mm T&E. It's a bit of an unusual find. The house was built in the 1930's but was rewired only recently, so I'm surprised to find such a situation.

Any thoughts ?

Is it a RFC? Have you tested for r1r2 and rn? R1+R2 ETC

 

[James]

Sounds like you've got daughters as well. driers, straighteners, chargers, music on full blast.....

I once went to a party as a guest and had to move several circuits onto a different phase because on top of the expected heating and cooking loads that were above and beyond normal,

8 to 10 of the fairer sex were upstairs in various rooms beatifying themselves with all of the above.
eventually they took out the 100A incoming fuse, the cable was hot to touch!

 

[telectrix]

Getting a bit tight if there are a couple of people who like to use hair driers etc at the same time, that is up to 16A on its own.

16A for 2 hair dryers?? sure they not paint strippers.

 

[James]

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[telectrix]

bloody hell.no wonder females have frizzy hair and fried brains.

 

[Mikegh]

I've not come across this before. The current regs state it should be on a 32A MCB. I've been asked to re-wire a bedroom which will involve extending this ring. It already serves two other bedrooms and the lounge. I know I probably should tell the client to upgrade this MCB to 32A, but is it necessary ? The ring is on 2.5mm T&E. It's a bit of an unusual find. The house was built in the 1930's but was rewired only recently, so I'm surprised to find such a situation.

Any thoughts ?

Maybe a long unfused spur was added with multiple sockets so they derated it

It's not great really RFCs being dropped down to 16/20 for various reasons. Somebody comes along after and changes it up to 32

 

[littlespark]

Maybe a long unfused spur was added with multiple sockets so they derated it

It's not great really RFCs being dropped down to 16/20 for various reasons. Somebody comes along after and changes it up to 32

If it was done by an electrician, to bypass a fault, then it’s a perfectly applicable solution.
It should have a test cert detailing the alteration, and as such, anyone else doing work to that circuit would have the information, and would not uprate the breaker.

 

[7029 dave]

As long as the various tests are carried out to confirm ring continuity correct cable sizing then upgrading to 32A is not a big issue.

 

[Mikegh]

If it was done by an electrician, to bypass a fault, then it’s a perfectly applicable solution.
It should have a test cert detailing the alteration, and as such, anyone else doing work to that circuit would have the information, and would not uprate the breaker.

Ah ok so the info is available

When you say bypassing a fault are u talking about removing a leg and dismantling the ring

 

[littlespark]

As far as the OP question, we dont know if there's info regarding why its been downrated.
Either there is a break in the ring somewhere, and its been converted to 2x radials, or part of the ring has been wired in 1.5 or something, which means a 32A cannot be used.

Sorry..."bypassing" wasn't the right choice of word.

 

[Risteard]

Quite common to find ring final circuits on 20A protective devices here. I must admit, it drives me nuts. Why go to the effort of installing and verifying a ring final circuit only to remove its primary benefit?

 

[Julie.]

bloody hell.no wonder females have frizzy hair and fried brains.

Hey!!!

I object to that, I haven't got frizzy hair!

 

[Zlodej]

I admit that I am one of those people who fit them.
Among reasons is when wiring bedrooms with a view to alterations latter for example when there was a possibility of house being latter converted to HMO or case when we were not sure if Gas arrives and as such giving excess number of rings for potential heaters. I am of a believe that if you can make something more safe then do so and where usage is expected to be low enough for B20. I would use B20 MCB providing protection and reacting under fault condition even when current enough to blow B32. Next point is that if you lose one of the cable contacts on a ring (break the ring) and your current flows via only one cable, It limits flow.
So I disagree with a term" "upgrade" to 32.
I fit smoke alarms on B3 MCB's.
I have also previously UPGRADED ring circuit MCB from B32 to more sensitive B16 on an ocasion when older wirings Zs was too high, but insulation test was still above 120M.
NOTE: As I have previously been refered to as possible troll for being one of those people against Rings I did made an attempt to avoid criticising them in this message to avoid flame (spark)

 

[Zlodej]

Quite common to find ring final circuits on 20A protective devices here. I must admit, it drives me nuts. Why go to the effort of installing and verifying a ring final circuit only to remove its primary benefit?

I would chanlenge you on that As many consider primary benefit of RFC to be secondary earthing (or connection route) should the cable gets disconnection or damage along the route.
While I am not a fan of RFC myself another of the benefits greater then its maximum fuse size is that in the event of lose or limited connection the other leg will have lower resistance and as such the resulted arcing is likely to be far lower to none, where on radial where there is no parallel path all current would have have to flow through it.