cable diameter

[studentspark]

Want to make sure a cable is the correct rating, have measured the thickness (diameter) of the copper conductor.

Red and Black twin and earth. Measured the line conductor and got between 1.7 to 1.85mm on my micrometer.

What size cable does that make it. It looks two thick for 2.5 but to thin for four. Probably just my eyes though.

Any help appreciated.

 

[timtheenchanter]

http://www.mathgoodies.com/lessons/vol2/circle_area.html

1.7/2 to give R = 0.85

square this = 0.722

0.722*3.14=2.26 so most likly 2.5mm

AFAIK 4mm and above is all stranded

 

[londonboy]

Could it be the old imperial stuff?

Grey sheath with stranded cores.

 

[timtheenchanter]

Ill go with not a good caliper (or usage there of)

using the higher gives 2.68mmsq.

 

[ban-all-sheds]

What size cable does that make it. It looks two thick for 2.5 but to thin for four. Probably just my eyes though.

Why look at it and try to guess when you've measured the diameter?

Work it out!

Seriously - if you can't cope with that level of maths then you should give up being a student spark - you're not cut out for it.

 

[SgtTrojan]

Harsh but fair but seeing as though this is a lad I may have taught I will try to help.

If it is flat twin and earth then there are three sizes of solid conductors, 1.0, 1.5 and 2.5 mm squared. 4.0mm squared is a stranded conductor as are all sizes above it.

Have you checked the sheath for markings?
Have you compared it against a piece of known cable size from another drum or source?
If it is the old T&E (referred to as 7/0.29 or something like that) it will be stranded and should be binned or replaced by now.

GL[/u]

 

[ban-all-sheds]

Don't need any of the stranded/solid, metric/imperial stuff.

1.7mm - 1.85mm diameter does not bracket 7/.029, it does not come anywhere close to 4mm², but it does bracket 2.5mm². In fact the mean is within 1% of 2.5mm².

Can't understand why studentspark was in any doubt.

 

[Adam_151]

The stranded/solid thing can be misleading!, there is such a beast as stranded metric 2.5mm² twin and earth. Seems to turn up quite a bit in schools, on buildings constructed or renovated in the 1990's