Lighting circuit taken off ring main somewhere

[Badged01]

Try Reg 433.2 to cover you for ommission of overload protection on a conductor ....

 

[Pete999]

Replace the 1.5 feeding the switch (replace switch with FCU) with 2.5 simples it aint rocket science it's in the OSG plain as the nose on your face, no arguments just do it right the first time as Mike Holmes says.

 

[D Skelton]

Put it this way, if I carried out a job whereby I fed a FCU with 1.5mm from a ring final and some muppet came arond telling the customer it's bad practice and against regulation blah blah blah... That is SLANDER! Plain and simple! If you then proceeded to charge the customer to replace it that is obtaining money by deception, a criminal offence!

Any of you idiots out there that continue to propagate this myth that somehow the 1.5mm cable isn't protected are talking out of your rear end. I would suggest that you start by picking up a bloody regs book!!!

 

[spark 68]

Replace the 1.5 feeding the switch (replace switch with FCU) with 2.5 simples it aint rocket science it's in the OSG plain as the nose on your face, no arguments just do it right the first time as Mike Holmes says.

Why?

Yes look at the guide for a guide (sarcasm), while at the same time ignoring the forward fusing rules (section 434) in the BGB.

Even the picture in App 15 tells us it does not cover other aspects of the design.

 

[ged noden]

If you can find which socket the 1.5 cable is fed from, then you can mount a spur unit next to it.
Quite simple.

 

[kingeri]

If I was installing this from scratch I would fuse down at the point of CCC reduction. If it was already present and as described by the OP, I would leave it as it is, there is absolutely nothing wrong with it.

 

[Badged01]

I would suggest that you start by picking up a bloody regs book!!!

OK, to continue the discussion I'll try ....... as I understand the regs the C/B is installed to protect the cable, which in this case I read it as a 32A C/B protecting the 1.5mm cable fed off 2.5mm cable. So the 1.5mm cable isn’t being overload protected by the 32A C/B.

But regs do allow that if due to the cable load characteristics it isn’t likely to be overloaded then overload protection isn’t needed --- provided there is fault protection. For the 12V lights connected via a transformer I’ll take this as holding true for overload and the 1.5mm cable is good to use without circuit overload protection.

However, Ive still got to provide fault protection for this 1.5mm cable even though I don’t need overload protection. I’ll assume an RCD so a L/E fault is taken care of but what about a L/N fault? Will the cable hold out before the 32A C/B or DNO cut-out “pops”?. Using the let thro current calc will probably show the 1.5mm cable can handle this energy and is OK to use.

But if it cant handle the fault, how do I now provide fault protection for the 1.5mm cable?

 

[spark 68]

The FCU need not be before or at the csa reduction point, it can be within 3m of it downstream.

 

[AndyL]

OK, to continue the discussion I'll try ....... as I understand the regs the C/B is installed to protect the cable, which in this case I read it as a 32A C/B protecting the 1.5mm cable fed off 2.5mm cable. So the 1.5mm cable isn’t being overload protected by the 32A C/B.

But regs do allow that if due to the cable load characteristics it isn’t likely to be overloaded then overload protection isn’t needed --- provided there is fault protection. For the 12V lights connected via a transformer I’ll take this as holding true for overload and the 1.5mm cable is good to use without circuit overload protection.

However, Ive still got to provide fault protection for this 1.5mm cable even though I don’t need overload protection. I’ll assume an RCD so a L/E fault is taken care of but what about a L/N fault? Will the cable hold out before the 32A C/B or DNO cut-out “pops”?. Using the let thro current calc will probably show the 1.5mm cable can handle this energy and is OK to use.

But if it cant handle the fault, how do I now provide fault protection for the 1.5mm cable?

Going round in circles here, see my earlier post. Fault protection will be supplied via the CB.

 

[Badged01]

Fault protection will be supplied via the CB.

True, if the 32A C/B can do the trick for 1.5mm cable?!?!. But the question was aimed that if the 32A C/B cant (and there isnt an FCU fitted for overload protection) how is fault protection now covered?

 

[AndyL]

True, if the 32A C/B can do the trick for 1.5mm cable?!?!. But the question was aimed that if the 32A C/B cant (and there isnt an FCU fitted for overload protection) how is fault protection now covered?

I understood from OP that there is FCU fitted, this give overload protection.

From reg 434.5.2 the 1.5mm cable will reach its limiting temp in about 1.6 seconds (assuming 160A fault current) As the CB will operate in about 0.1 seconds, at this current, fault protection is afforded

 

[Badged01]

I understood from OP that there is FCU fitted, this give overload protection.

Sorry if my reply has confused but the thread is directed along there being no FCU fitted for protection, hence my question for how to protect for fault current in the unlikely event that the 32A C/B cant!.

 

[AndyL]

If there is no FCU then overload protection would indeed be required, fault protection is still given by 32A CB

 

[Zeus]

you are right that you can take lighting off a ring final circuit and I know its bad practice to use 1.5mm cable to do the first leg of that circuit extension with but as 1.5mm can carry up to 16A, that first leg will only be carrying the load of the lighting to which you will have a 5A fuse in series. so I would make sure firstly that the 1.5mm does not form part of the ring final circuit and if this proves so then I would have said it is ok to remain. just note as a code 3 on your report.

 

[Guest55]

youre all missing the point !
the OP declared this to be an eicr , therefore the only discussion should about the coding if any.
and IMO its probably a C2 - but a 2 minute fix with a switched fused spur.

 

[Badged01]

youre all missing the point !

You're being far too serious and stopping us having all this fun and banter to liven up the day

 

[Guest55]

im never serious !
seriously.
;-)

 

[GLENNSPARK]

but even after prominant members in here made it quite clear that it was acceptable to use a 1.5 as a feeder to an FCU there were still several others continuing blubbing on about how they would rip out the 1.5 and replace with 2.5....
an unneccessary nonsense if you ask me
christ, what do some in here think we fuse down for?

 

[shanky887614]

but even after prominant members in here made it quite clear that it was acceptable to use a 1.5 as a feeder to an FCU there were still several others continuing blubbing on about how they would rip out the 1.5 and replace with 2.5....
an unneccessary nonsense if you ask me
christ, what do some n here think we fuse down for?

The fun of it?

Lecky takes easiest route so splicing cable then adding fcu would be more than adequate.

If i was installing myself though id probably use 2.5 to fcu but woudlnt replace if it was done in 1.5

 

[telectrix]

but even after prominant members in here made it quite clear that it was acceptable to use a 1.5 as a feeder to an FCU there were still several others continuing blubbing on about how they would rip out the 1.5 and replace with 2.5....
an unneccessary nonsense if you ask me
christ, what do some n here think we fuse down for?

prominent, glenn. get a grip, man. :angelsad2: