Spot the error

[GaryMo]

Terminal shrouds missing on incomer.

That doesn't matter in this picture anyway - the isolator is on

Apart from general untidyness there's nothing there that looks out of place and couldn't be explained by the design of the circuit.

you mean appart form the single 2.5 cable being protected by a 32a breaker???

It might be feeding one twin or single socket or a FCU.

 

[ColJack]

doesn't matter... it should not be protected by a breaker that is bigger than the current carrying capacity of the cable unless it is a ring main...

( I've started another thread to argue the point.. )

 

[GaryMo]

Col, give us a regulation that contradicts it.

With your logic in mind what would you supply a 32A switch fuse with that will originate from an 200A busbar?

 

[Lectrician]

The only error I was looking for really was the 40amp MCB feeding a ring final circuit. A few sockets in a few bedrooms. They apparently had trouble with tripping (portable oil rads), and this was some clever soles solution a good while back. It has been like it for years.

 

[ColJack]

433.1.1 ( please see other thread for reasons.. )

as for the 32A switch from a 200A busbar.. that would depend entirely on it's location..
presuming it's attatched and coupled to the busbar such that the cable does not exit the enclosures, then a cable suitable rated for 32A will suffice
that is down to the specific regulation that allows the "fusing down" to take place AFTER the reduction in CSA provided that it's less than 3m from where the change in CSA occurs, and that it is installed in such a manner to reduce the risk of a fault to a minimum and to reduce the risk of a fire or danger to persons to a minimum.. ( IE reg 433.2.2 )

so on that basis then yes you can put JUST a single socket or a double socket on a 32A breaker but it needs to be within 3m ( cable length ) of the breaker...

 

[Lectrician]

433.1.1 ( please see other thread for reasons.. )

as for the 32A switch from a 200A busbar.. that would depend entirely on it's location..
presuming it's attatched and coupled to the busbar such that the cable does not exit the enclosures, then a cable suitable rated for 32A will suffice
that is down to the specific regulation that allows the "fusing down" to take place AFTER the reduction in CSA provided that it's less than 3m from where the change in CSA occurs, and that it is installed in such a manner to reduce the risk of a fault to a minimum and to reduce the risk of a fire or danger to persons to a minimum.. ( IE reg 433.2.2 )

so on that basis then yes you can put JUST a single socket or a double socket on a 32A breaker but it needs to be within 3m ( cable length ) of the breaker...

Kind of.

Your busbar scenario - also a min of 4mm CSA.

Your socket scenario, the 3m length, extra mech protecion and 4mm min CSA rule does not apply - the 30/32 amp device still provides fault protection to the 2.5mm, and the plug top fuses provide the overload protection.

 

[GaryMo]

433.1.1 ( please see other thread for reasons.. )

as for the 32A switch from a 200A busbar.. that would depend entirely on it's location..
presuming it's attatched and coupled to the busbar such that the cable does not exit the enclosures, then a cable suitable rated for 32A will suffice
that is down to the specific regulation that allows the "fusing down" to take place AFTER the reduction in CSA provided that it's less than 3m from where the change in CSA occurs, and that it is installed in such a manner to reduce the risk of a fault to a minimum and to reduce the risk of a fire or danger to persons to a minimum.. ( IE reg 433.2.2 )

so on that basis then yes you can put JUST a single socket or a double socket on a 32A breaker but it needs to be within 3m ( cable length ) of the breaker...

It's 433.2.2 (i) AND/OR (ii)

Read the end of 433.2.2 - at least ONE of the following conditions.

And on that basis it can be after 3M.

 

[Paul_C]

I don't think the 60A Wylex standard boards had any position rated for over 30A. The busbar and terminals are certainly hefty enough, but exceeding manufacturer's specifications I would say. Was the lug on the 40A carrier filed down?

 

[flameport]

Was the lug on the 40A carrier filed down?

The new ones don't have the lug on them, so any rating can be shoved into any board by anyone.

 

[WabbitPoo]

Its frightening how qualified electricians (I presume you are all qualified, anyway) can disagree so much when you have one of the more highly regulated professions.....all those lovely regs, I mean. Doesn't insipre confidence, chaps....

 

[GaryMo]

There will always be opinions depending of individual interpretations of the regulations though some people get caught up in 'it's not good practice so it can't be right'.

 

[ColJack]

highly regulated, yes... but not exactly easy reading..
as with any book the wording is important but the "meaning" is interpreted slightly differently by whoever the reader is..

if it was written in plainer english with "you MUST do this... and you MUST NOT do this.." style then it would be black and white.. but it contradicts itself on so many occasions for differing circumstances..

 

[mfarrow]

With your logic in mind what would you supply a 32A switch fuse with that will originate from an 200A busbar?

Using 433.3.1 (ii), anything you like if it can take the expected fault current, and at any distance possible from the supply.

 

[NotHimAgain]

Its frightening how qualified electricians (I presume you are all qualified, anyway) can disagree so much when you have one of the more highly regulated professions.....all those lovely regs, I mean. Doesn't insipre confidence, chaps....

It would appear that you misunderstand the purpose of BS 7671 – Requirements for Electrical Installations. This is a British Standard that addresses the design, erection and verification of electrical installations. It is not an instruction manual for electricians - the last set of regulations that even remotely fulfilled that purpose was the 14th Edition, and that went out in 1981.

That is not to say that it does not contain any guidance at all, but the guidance given tends to be as broadly targeted as possible so as to allow a whole range of solutions, without being unduly prescriptive.

So it is little wonder that electricians disagree from time to time over the best way to apply some of the guiding principles embodied in BS 7671.

 

[ban-all-sheds]

Sometimes because they cannot or will not read.