does this comply?

[ADS]

ooh! look iv found something else useful. It shows below 3Ka pfc 1.5 cpc in 2.5t&e is ok, but above this up to 6Ka pfc a 2.5cpc needs to be used. So t&e is no good, but singles in conduit will still be ok. ?:|

I don't get how the size of the CPC is going to be an issue, as soon as 30mA of fault current flows the circuits disconnected in 0.04 seconds - or am I missing something.

Also, you still have the fact that 2.5/1.5 mm is allowed to spur off a 4mm radial, so PFC can't be an issue anyway.

 

[Andy™]

Nicky I have a feeling no matter how much you prove there is no danger of a bit of 2.5mm on a 32A breaker with overload protection downstream some people will not accept it. Possibly would even be code 1 for some people. The greatest obstacle to discovery is not ignorance -- it is the illusion of knowledge.

if you give something a code 1 that is safe, then you shouldnt be doing a PIR

 

[ianmacd]

I don't get how the size of the CPC is going to be an issue, as soon as 30mA of fault current flows the circuits disconnected in 0.04 seconds - or am I missing something.Also, you still have the fact that 2.5/1.5 mm is allowed to spur off a 4mm radial, so PFC can't be an issue anyway.

An RCD maybe? OP didn't mention there was one.

Also I know its in the diagram but you still have not been able to point to a reg that allows that unlike the ring variety.

 

[ianmacd]

[quote name='Andy

 

[Andy™]

An RCD maybe? OP didn't mention there was one.

yes he did

32A RCBO feeding two 2.5mm cables with a switched fused spur or single socket on the end. So one point per cable.

 

[Andy™]

I guess I could agree that it may not be a code1 but a code4 .

if it complies, you cant give it 4.

only time you would be able to give a code would be if it was proven the earth was undersized to carry fault current to operate fault protection. but then that also applies to every other circuit

 

[ianmacd]

It doesn't comply with 7671:2008 (according to IET) so code 4 it is.

 

[Andy™]

It doesn't comply with 7671:2008 (according to IET) so code 4 it is.

depends how you interpret the regs....

but at least you wont be jumping straight in with code 1 and telling customer its dangerous and needs disconnected

 

[ianmacd]

Not sure we could do that as its been pointed out its safe even if its compliance can not be agreed.

 

[Manator]

I and other moderators have allowed this thread to continue because some very interesting questions were raised during the discussions.

Many strong willed views based on good installation practices have been aired, along with practical matter of fact regulation and interpretation.

What I do dislike about this thread is the fact that people get personal, with blatent attacks on another persons credability, and right to reply.

What I have concluded by reading all posts is that whilst it would never be designed this way by the majority of posters, many concluding it would be bad practice to do so, if found through any PIR would not offer a code as regulations would allow it by definition.

I am not going to close or lock this thread because it is important that all learn from its content, but I will delete any post which I believe is directed at another persons view which is different to their own, and give infractions to offenders.

Reasonable debate is the only requirement and one of the reasons why this forum can conduct such debates.

I would like to thank all those who respect this, and stay within fact and post with conviction but without malice.

 

[DarkInferno]

I've been reading this thread since it was first created, I have found it extremely interesting. Thanks to all involved

(I came down on the side of it would comply, not great design, but still)

Only idiots thought it wouldn't comply anyway <=- Obvious joke alert.

 

[Badger]

I've been reading this thread since it was first created, I have found it extremely interesting. Thanks to all involved (I came down on the side of it would comply, not great design, but still)

Only idiots thought it wouldn't comply anyway <=- Obvious joke alert.

:red card heres your :coat :^O

 

[wozz]

I if found through any PIR would not offer a code as regulations would allow it by definition.

I wonder if many people out there have coded this situation many times on PIRs and now wouldnt after this debate.

 

[kme]

Wellllllll - here`s an interesting update.

Last week, I posted the following off to the "technical helpline" guys at the NIC (yes, I KNOW they don`t make the rules.....etc.....etc):

Dear sirs:

I am a founder member of one of the largest electricians forums in the country.

Recently, a question was asked, as follows:

"32A RCBO feeding two 2.5mm cables with a switched fused spur or single socket on the end. So one point per cable. Does this comply with regulations?"

Initially, my answer was a definite no, however, having read 433.2.2 four times, I now think it may. However, there is another school of thought, who say that the protective device (in the case of a socket outlet) is within the plug, then the protective device will be beyond the socket outlet (i.e. in the plug), therefore it doesn`t comply.

I would value your input on this, as respected members of your field.

I had a telephone call back yesterday:

They apologised for the length of time taken to reply - they couldn`t actually agree between themselves.

General concensus was that, if possible, a call to the designer to query their reason for this design would be the first instance. They`d want to code it, but admit that, if the designer came back with a valid reason for that design, they`d be "sort of stuck" without a reg. to back up their position.

KME

 

[steptoe]

[quote name='Andy

 

[Andy™]

OK,I will agree with this on one condition,

can someone give me a reg that allows 2X2.5mm T&E radials to be taken off 1 32a MCB, considering that 2.5mm can only at best carry 27amps.

this is very much in the broken ring final scenario, so why do we bother downrating the MCB then, couldnt we just say we have re-designed it into 2 radial circuits? (assuming the break is somewhere along the midpoint, same size cable and protected by a fuse at each outlet.

we already have a possible 26a(actually much more if protected by 1361) load on our OP circuit, which we all know the 2.5 is very unlikely to be in ideal conditions to carry.

its not a broken ring scenario. in this case, its one outlet per 2.5. in a ring, it would be many outlets to a 2.5. both very different.

and the radial diagram in the BRB clearly shows 2.5 being taken from a 32A 4mm radial circuit.

 

[steptoe]

[quote name='Andy

 

[ADS]

show me the reg that states it is fine to have a 2.5mm radial protected by a 32amp protective device in BS7671 please.

You will agree that the 32 Amps is the protective device's 'overload' rating?

You are also aware that neither of the two radials in the ops scenario are capable of being 'overloaded'

So the regulation that you require that specifically allows you to ignore the 32 A 'overload' rating is.............

433.3.1 (ii) ....overload protection is not necessary for a conductor, which, because of the characteristics of the load, is not likely to carry

overload current.

It is because of this regulation (433.3.1 (ii)), that the regs allow you to run a 2.5mm, unfused spur from a 32A ring final or a 32A 4mm Radial - because it can't be overloaded as long as it feeds only one single or one double socket

.

Oh, and keep it nice, please, Steptoe

 

[kme]

I have to agree with ADS on this, Albert

Much as I don`t like the idea that it could comply; I am willing to accept that 433.3.1 does, indeed allow for this - if necessary

KME

 

[Sidewinder]

Methinks email to Geoff &/or Mark @ IET tomorrow to see what they say!

When I get chance I'll read this danm thread!