Same Sockets from 2 different MCB's?

[JohnW2]

Please state what regulation, can't think of one, as to danger with a single 32 amp MCB any large load near the origin of the ring can cause an overload, with two 16 amp MCB's linked neither leg can be over loaded so if anything safer.

"Linked" MCBs is a totally different issue - and something I have never seen in a domestic CU, so really a red herring.

As to if not linked, with a three phase supply motor could single phase, but in a single phase supply only danger is if some one does not test for dead.

I've mentioned that danger - which, in itself, is probably enough to make it non-compliant. However, as I also said, there is also the issue of disconnection times. A fault near one end of the ring would leave relatively little current flowing through one of the MCBs until the other one operated, which could almost double the time before both ends of the circuit were disconnected, and hence the fault cleared.

As with fig 8 I think not following normal practice is wrong even if no rules broken, but as with fig of 8 can't see what rule is broken using two 16A linked MCB's.

As above, 'linked' RCDs are a red herring, at least in relation to domestic installations. Two 'ordinary', unlinked MCBs (one at each 'origin' at the CU) would be just as bad with a figure-of-8 than with a simple ring.

Kind Regards, John

 

[JohnW2]

Two things may have gone wrong, one is some one has in the past wired the conservatory as a figure of 8 ....

I don't see how that could produce the situation the OP described - since, just as with a normal ring, both ends of the primary ring should be connected to the same MCB.

The second is some one, may have even been the guy doing the testing has swapped two wires in the consumer unit.

Yep - or it had always been like it is and testing was never done properly. However, that is equally true whether it is a simple ring or a figure-of-8.

As to whether or not a figure-of-8 is compliant with regulations, I suspect that many would say that since it is not a simple ring final, then, strictly speaking, it probably cannot enjoy the dispensation to have 2.5mm³ cable protected by a 30/32A OPD. However, in electrical terms, I see no real problem, and no 'danger' (in some senses the converse), the only real problem being the potential confusion/difficulty in relation to testing.

Kind Regards, John

 

[Taylortwocities]

Clearly the fault needs tracing and correcting as one could draw 64 amp from the system and could be a serious overload.

How could it possibly do that? The MCBs do not double in their capacity, they have a 32amp trip characteristic!

 

[John D v2.0]

How could it possibly do that? The MCBs do not double in their capacity, they have a 32amp trip characteristic!

Each one has a rating of 32, so if you got an overload at the centre of the ring, you could pull 32 amps from each direction without ever tripping anything.

 

[John D v2.0]

Landlords especially private are generally more relaxed than people like ban all sheds about regulations.
For example we moved into one place which had obvious bare live wires dangling from the ceiling and the light itself wasn't fixed to the ceiling. This was over the bed and very low ceilings ie about 2.2m or so.
The previous tenant mentioned they'd changed the fitting while they were there. The landlady told us it was fine when we pointed out out would need sorting. She then the a fit when we fixed it ourselves and tried to Bill her for the parts only (about 20 pounds by the time we fixed all the other small issues) on the basis she didn't approve the repairs! Imagine if we tried to tell her the socket rings were not connected to the same MCB at both ends! No chance!

 

[ericmark]

The main point is it needs fixing. To my mind down to landlord. However once some one plays with an installation then it is up to them to leave it in a safe manor. So this is the real rub, if I had been doing the work for my daughter, once I found the problem I would have stopped.

 

[ban-all-sheds]

Landlords especially private are generally more relaxed than people like ban all sheds about regulations.

If by "relaxed" you mean delinquent, and by "people like ban all sheds" you mean people who think electrical installations should be safe, I agree.

 

[John D v2.0]

by "people like ban all sheds" you mean people who think electrical installations should be safe, I agree.

If I did a survey on here, I'm sure that would be the first thing that would spring to everyone's mind

 

[Doggit]

He clearly doesn't think he should have the electrical installation inspected on a change of tenant

No legal requirement to do that I'm afraid, and I think the regs allow you to change a socket without being part P qualified, so this shouldn't be an issue. If the landlords doesn't resolve the issue, then the tenant can raise the issue with his Environemental Health department at the council. An inspection of the CU shoul tell if there's 2 circuits in the same MCB, and if there is only one perMCB, then that suggest a more serious issue, so yes, suspect inspection.

Fortunately, the landlord can't do a revenge eviction nowadays.

 

[JohnW2]

An inspection of the CU shoul tell if there's 2 circuits in the same MCB ...

Unless the cables are labelled (and labelled correctly) it would take some testing as well as just 'inspection'. With a ring circuit, there should be conductors from two cables connected to the MCB, the question being whether they are conductors from the correct two cables.

Even if the cables were labelled, and appeared to be connected to the correct MCBs per that labelling, one would still have to do some testing, since it could be that incorrect labelling is what had caused an error of connections to the MCBs.

Kind Regards, John

 

[ban-all-sheds]

No legal requirement to do that I'm afraid

I never said there was.

and I think the regs allow you to change a socket without being part P qualified

The law does not allow you to do it if you are so incompetent that you cannot do it safely.

And therein lies the problem. Somewhere in law, AIUI, is that a landlord has a duty of care, and if he allows people of unknown competence to do electrical work in his properties, and combines that with not checking when they leave that they have not done something dangerous then IMO he has failed in that duty to the next tenant.

(Part P is a Building Regulation, not a qualification, BTW)

An inspection of the CU shoul tell if there's 2 circuits in the same MCB, and if there is only one perMCB, then that suggest a more serious issue, so yes, suspect inspection.

Almost certainly what has happened here is that a numpty tenant or a numpty not-actually-an-electrician has got the ends of 2 rings mixed up.

Either way, for the landlord to have allowed that to happen is a dereliction of duty.

 

[SimonH2]

Landlords especially private are generally more relaxed than people like ban all sheds about regulations.

Oi, please make that "some" landlords - most of us take these things quite seriously. I certainly take safety in my properties more seriously than most owner occupiers.

Almost certainly what has happened here is that a numpty tenant or a numpty not-actually-an-electrician has got the ends of 2 rings mixed up.
Either way, for the landlord to have allowed that to happen is a dereliction of duty.

And I agree 100% with that. I would be completely livid if I found that a tenant had interfered with (in this context) the electrics without discussing it with me first. And if they did discuss it with me first, then I'd be looking carefully at what was proposed to be done, and by whom, with it being done safely my first concern. Of course, coming a fairly close second would be "does it 'devalue" the property in any way".

 

[John D v2.0]

Oi, please make that "some" landlords - most of us take these things quite seriously. I certainly take safety in my properties more seriously than most owner occupiers.

To suggest that ban all sheds merely takes regulations "quite seriously" is probably the biggest understatement I have heard today.

Even if you're claiming to be at least as fastidious as he is, then I'd still stand by my "generally more relaxed" qualifier.

 

[ban-all-sheds]

So you think that it is OK for a landlord to be relaxed about allowing incompetent tenants to create dangers in the electrical installation?

 

[John D v2.0]

So you think that it is OK for a landlord to be relaxed about allowing incompetent tenants to create dangers in the electrical installation?

who was that directed at, and in response to which statement?