Cable Sizes

[elec2012]

Random question, What does the size of a cable in mm2 relate to... i can tell for example by looking at a T+E cable that it is 16 mm but what is 16mm? its obviously not the diameter of the cable. sorry if this is a silly question! cheers headbang

 

[paul b b]

Its the cross surface area ..csa

 

[ParkySparky]

Cross sectional area of the core.

 

[elec2012]

but surely that means if you measure the core with a micrometer that would give the size of the cable but it does not...

 

[wozz]

crbvcurbvubruvbruvb

Its area to you need a bit of Pi

 

[Sidewinder]

elec,

Please tell me this is a windup, or a joke?

Was this not covered in your training?

Or, are you a DIY'er?

If you were not taught this & have done a relevant training course then you were ripped off & you need to take the training provider to court for fraud.

Sorry this sounds harsh, but such understanding in fundamental underpinning knowledge.

If you are a DIY'er, or have not yet begun training, then I apologise profusely, and ask for your forgiveness & would suggest that you ask for this to be moved to either the DIY or the Student areas.

 

[paul b b]

If you measured it with a micrometer it would give you the diameter would it not

---------- Post Auto-Merged at 18:40 ---------- Previous post was made at 18:39 ----------

Diameter pie r square is what you need

 

[kerching]

Think about it....rulers measure distance so do micrometers in mm. NOT Cross sectional area in

mm2

 

[sellers]

If the cable was 1mm thick by 16mm wide it would be 16mm2

But then it wouldnt be very easy to install, this cable is round!! Back to school with the radius, circumference and diameters.

 

[Doc Hudson]

but surely that means if you measure the core with a micrometer that would give the size of the cable but it does not...

Your logic would suggest that you have never seen a non-circular conductor. What is the CSA of an oblong cross sectional bus-bar, the width, depth or height? Nor have you seen how some two core SWA cables have conductors with a flatter face making two semi-circular areas that fit better inside an overall circular cable. 25mm would be nearly an inch in old measurements, those would be some very large tails. Note the significance of mm or mm2{squared} .

Doc H.

 

[Nicky Tesla]

just a side question to the above, but on 16mm split concentric cable on existing DBs, what size earthing conductor do you all write down on your PIRs?

---------- Post Auto-Merged at 19:48 ---------- Previous post was made at 19:36 ----------

i have just checked cleavland cable site and their 16mm-split-concentric cable for the live and neutral cores is made up of 7x1.7mm2 strands. Now that only adds up to 11.9mm2 which is smaller than the stated 16mm, and for some reason doesnot show the earthing conductor strands.

1.q.1 - Concentric Split single phase service cable, 4mm to 35mm

 

[Sidewinder]

SplitCon does not meet the requirements of BS7671 and thus cannot be used officially AFAIK, but I will check.

 

[Nicky Tesla]

it is used a lot round here for dno db supplies

 

[Sidewinder]

DNO can use it, they don't comply with BS7671.

After the cut out it is not a recognised cable type.

Not all live conductors are surrounded by an earthed metallic sheath are they.

 

[kerching]

just a side question to the above, but on 16mm split concentric cable on existing DBs, what size earthing conductor do you all write down on your PIRs?---------- Post Auto-Merged at 19:48 ---------- Previous post was made at 19:36 ----------

i have just checked cleavland cable site and their 16mm-split-concentric cable for the live and neutral cores is made up of 7x1.7mm2 strands. Now that only adds up to 11.9mm2 which is smaller than the stated 16mm, and for some reason doesnot show the earthing conductor strands.

1.q.1 - Concentric Split single phase service cable, 4mm to 35mm

NO THEY ARE NOT

They are made up of 7 x 1.7mm diameter cables. This works out at 15.889 mm2[0.85 x 0.85 x 3.14159 x 7]

So it is near enough 16 mm 2

 

[Sidewinder]

Nicky,

Perhaps you should look to the title of the standard for this cable first:

[h=2]BS 7870-1:2011 LV and MV polymeric insulated cables for use by distribution and generation utilities. General.[/h]

 

[Nicky Tesla]

ye i know sides, but i have to put the size of the earthing conductor on the certs and many boards i come across especially in flats have been fed from the meter to the DB with split-con cable.

---------- Post Auto-Merged at 15:44 ---------- Previous post was made at 15:36 ----------

ok found doncaster cables and it shows earthing conductor as 4x2.25 strands which works out as 15.89mm2 so that is confirmed.

i just accepted it before now.

 

[Sidewinder]

OK Nicky,

I take your point, but, you can't give an acceptable EICR with this cable present anyway, so the earth conductor csa is a little irrelevant really.