Need 2nd opinion on cable.......

[Guest55]

this has been bugging me for weeks..........
been using Fp200 for all socket / lighting circuits on current project , the usual 1.5/2.5 stuff
and im almost sure , but not 100% , that the tinned solid core cpc is the same size as the L / N ??
its certainly not a 1mm earth in the 1.5 cable......
had a quick nosey on a cable website but found nowt conclusive.
anyone else confirm or know different ?

 

[tbs1983]

perhaps because it isnt as good a conductor as copper they use the bigger csa size in order to keep earth loop impedance down ??? ( just a though)

 

[Guest55]

it is a copper conductor , but tinned on the outside.
a good point to raise though.

 

[ian.settle1]

Try this link

Prysmian cable provides protection in the City - Edmundson Electrical

Then click on the data sheet link at the bottom

 

[Guest55]

thanks ian but still doesnt mention cpc size like the other cable website i checked.

i can only deduce that the cpc is the same csa as line as a reduced size would need to be noted in the manuf. data.

something needs to be recorded on the cert for earth size so im going with my gut.

 

[Marvo]

Can't you measure the diameter with a vernier and manually calc the CSA?

 

[Guest55]

Can't you measure the diameter with a vernier and manually calc the CSA?

nope , got no verniers..........
but i could measure resistance on a spare piece - if E csa = L csa , then L-N & L-E should be the same on a continuity test

i just thought someone may have come across the same issue previously , especially when the time comes to fill in cert and youre not on site lol.

 

[Marvo]

i just thought someone may have come across the same issue previously , especially when the time comes to fill in cert and youre not on site lol.

I haven't seen a similar question so they've probably just made a wild guess

The resistance method would be pretty accurate especially if you have a longish piece of cable you could also size it using reference tables for copper wire resis/meter.

 

[Guest55]

a wild guess


size it using reference tables for copper wire resis/meter.

i'm leaning towards option 1 on a lazy saturday afternoon lol
;-)

 

[KAS1]

Check manufactures data / your cable supplier, it's no good just being "almost sure" now come on get a grip.

 

[Guest55]

Check manufactures data.

WTF do think i've been doing with ians link in post #4 ?
;-)

 

[Knobhead]

Same size

Buy Prysmian Fire Resistant Cable, Red, 100m, Annealed Copper 1.5mm², Three Core - FP200H1.5RED

 

[MarkieSparkie]

BS 7629 requires fire cable (FP200 etc) to this standard to have all cores of the same CSA.
Firecable BS 7629 - Enhanced | UK Cables

 

[Knobhead]

Fire Resistant
Red
100m
1.38mm (Strand)
100m
Three Cores of Plain Annealed Copper 1.5mm²
1.38mm (Strand)
12.1ohm/km@20C (Conductor)
300-500V

PS Tinned copper is better than plain

 

[Guest55]

Same size

i knew it ! lol , just thought i'd kill time with the ensuing debate. ;-)
marvo's right tho , never seen it mentioned in any other topic which is strange considering its wide range of applications / uses.

 

[ipf]

Is the earth core smaller when you use one of the cores in a SWA ?

 

[GLENNSPARK]

perhaps because it isnt as good a conductor as copper they use the bigger csa size in order to keep earth loop impedance down ??? ( just a though)

no....do you not think the terminal screws wouldn`t get through the tinning?

 

[Guest55]

Is the earth core smaller when you use one of the cores in a SWA ?

no , but then swa isnt the same as fp200 is it ?

 

[MDJ]

A very good question I thought and to answer it the bare conductor is the same size as the sleaved pvc conductors Biff

 

[Deleted member 72666]

I've also come across this when doing a eicr, the lighting circuit in the cellar was in 1.5mm fp200 with a tinned copper 1.5mm cpc, the radial sockets however were fed with a 2.5mm fp200 cable with a 2.5mm stranded tinned copper cpc.