Ring Main Breaker Size

[benlwatts]

Hi Guys,

Recently I had an issue with a ring main in my flat either the circuit was over loaded or the connection at the breaker was poor. Either way it ended up with a burnt out breaker with black scorch marks on the top and melted cables by the breaker. As the flat is rented i'm unfortunately not allowed to change anything with out prior approval from letting agency.

Where i'm going with this is i'm pretty new to the whole trade and don't want to question the electrician they sent to fix it but i'm concerned that he has oversized the breaker. He's replaced the broken 32A with a 40A the ring main is wired with bog standard 2.5mm T+E. I'm pretty sure if i've remembered my teachings right that at most for a ring main it is 32A. Should i be questioning this ?

Ben

 

[Octopus]

Sounds like loose connections to me

 

[benlwatts]

Thats what i thought it was, But what i'm questioning is the electrician replace the old 32A breaker with 40A for a ring main using 2.5mm cable ?

 

[telectrix]

either that, or one of those faulty electrium breakers subject to recall. unusual to fit a 40A though.

 

[Octopus]

Thats what i thought it was, But what i'm questioning is the electrician replace the old 32A breaker with 40A for a ring main using 2.5mm cable ?

Oops, sorry mate. yes, get him back as I wouldn't be running a 2.5mm T&E ring on a 40A breaker

 

[Pete999]

Yes a 32Amp breaker is the way to go, the guy that fitted the 40amp probably it was all he had or he was to lazy to go and get the proper breaker

 

[telectrix]

weird, that, coz. in general we usually have loads of 32A going spare after replacing with 16A or 20A when we do board changes and find 2 radials in a 32A.

 

[Deleted member 9648]

Reg 433.1.5 specifically lists 30 or 32a protective devices only in the requirements for standard ring circuits,so a 40a device does not comply.

 

[SPARTYKUS]

Maybe..... Hes coming back, and was concerned the existing MCB was faulty so stuck (an albeit too large) valued new MCB in its place.

i would prefer a new 40A mcb than a clapped out 32A one. Even if its just for a day.

am i bad

 

[Deleted member 9648]

Maybe..... Hes coming back, and was concerned the existing MCB was faulty so stuck (an albeit too large) valued new MCB in its place.

i would prefer a new 40A mcb than a clapped out 32A one. Even if its just for a day.

am i bad

Shockingly bad.....but yes,nowt wrong with a temp 40a to get things going. Much wrong with an RCD replaced with a main switch to stop it tripping as I saw recently,and he charged the bloke £400 quid to do that.

 

[SPARTYKUS]

I'll take that bad

 

[SPARTYKUS]

P.s. At least they replaced the RCD with something. - Ive seen the RCD butchered open and bodged with a bit of cable INSIDE the rcd then taped back together.....

 

[uksparks]

Whilst on the subject of RFC breaker sizes, I went to a job the other week because the lady said the MCB kept tripping when several appliances were on...

it it was a ring as I tested it, in 2.5/1.5, well that's what it appeared to be in the CU, had end to end continuity etc.

the circuit was protected by a 16A breaker though.

as it happens she didn't ask me back as the landlord got someone in, but what are your thoughts on changing a breaker for a bigger one as I was tempted to swap it for a 32A but then thought, why is it a 16A, am I missing the obvious? MYbe the person who fitted it did it for a reason.

whats your thoughts on upping it?

 

[telectrix]

if you#re sure it was a RFC with e-e continuity, then fitting a 32A would be fine. a possibility though is that there could be several unfused spurs off the RFC and a previous spark downrated the MCB to allow for the spur loading.

 

[uksparks]

That's my thinking, I guess without pulling every faceplate off and going back to basics you will never know 100%.

its one if those things where I would rather take a miss on it just incase, for what it's worth it's bit always worth the potential hassle.

 

[Engineer54]

We have in places installed 40A breakers on 4mm RFC's, mainly in cafeteria service areas. But then we have a minimum conductor size of 4mm for all power/socket circuits on this project....

 

[ImpededLoop]

That's my thinking, I guess without pulling every faceplate off and going back to basics you will never know 100%.

its one if those things where I would rather take a miss on it just incase, for what it's worth it's bit always worth the potential hassle.

What's the Zs of the circuit? It may be that the installer only had a 16A breaker and never got round to replacing it with a 32A.

 

[uksparks]

What's the Zs of the circuit? It may be that the installer only had a 16A breaker and never got round to replacing it with a 32A.

No idea, didn't do the job in the end anyway

 

[egg67]

When we go to a job with tripping MCB, RCD, do we not do all the test to find out the problem or do we just look and go away, then ask on here what people think but say someone else fixed it as I would not put my name to it as I was not able to spend the time to fix it as I was going home for a nice cold beer and had to post a pic on this site to get lots off likes or just get into the 3000 club, your there just test it then fix it put bill in get paid, it's what we do, you can not go on about DIY'S not doing it the right way if you leave a job without knowing what is wrong and fixing it, this is not having a go at anybody but just think sometimes Q&A can get silly
And yes I have had a beer, got home early as fixed problem by testing first then fixing 2nd