4mm radial

[sedgy34]

has anyone spured off a 4mm radial in 2.5mm on 75 mtrs circuit length on 32A mcb

 

[Geoffsd]

It depends on whether the test is to ensure the opd will operate or

to find out if you have connected all the wires.

The EIC requires maximum​ Zs.

 

[Strima]

Just goes to show the variability of assessors, I know someone in ECA/Elecsa who continually preaches the Zs = Ze + R1 + R2 calculation and EIC entry

I personally don't like calculated Zs on an EICR unless I really have to. I doesn't give you a true picture of what is happening with that specific circuit within an installation, parallel paths etc.

 

[Geoffsd]

I personally don't like calculated Zs on an EICR unless I really have to. I doesn't give you a true picture of what is happening with that specific circuit within an installation, parallel paths etc.

No, but that is the point.

You need to ensure that the opd will operate if the parallel paths are removed in the future.

As I said, I do not consider a measured Ze (without parallel paths) and a measured R1+R2 to be what is meant by a 'calculation'.

 

[Strima]

Geoff, I see your point. We could debate this until the bovines come home. :lol:

There are valid reasons for both methods, otherwise they wouldn't be accepted as test methods. In a domestic installation there is little likelihood of circuits being removed but in industrial and commercial there is. I think it would be down to the tester at the time to make an informed decision as to what method to use and even both if the need arises or is requested.

 

[sedgy34]

Would like opinions on the original question

 

[Geoffsd]

has anyone spured off a 4mm radial in 2.5mm on 75 mtrs circuit length on 32A mcb

I haven't.

Ok if all conditions met - vd, efli, only one socket/appliance etc.

 

[Strima]

It has gone off topic a bit...

Dependant upon intended use, load, CCC and voltage drop .

BGB is in the van but BRB page 363 Fig 15.

Unfused Spur on a 30A or 32A ocpd.

An unfused spur run in 2.5mm2 cable should feed one single or one twin socket outlet only. An unfused spur may be connected to the origin of the circuit in the distribution board.

It all boils down to voltage drop and what the intended load is.