# sqmm + mmsq

#### soulman

Joined Jun 15, 2006
1
Hi,

Can you please tell me what is the differance in the 2?

With regards to 2.5mmsq cable which is the CSA of a copper conductor, does this mean the area of the circle as a whole? or is it the width of the conductor it is refering too?

And am I right in thinking because of pi formula! that 2.5mmsq + 2.5mmsq does not equal 5mm sq? And if so could you tell me the formula please.

This is an ongoing dispute on another forum.

Kindest regards

Soulman

#### Papabravo

Joined Feb 24, 2006
15,562
Originally posted by soulman@Jun 15 2006, 02:39 PM
Hi,

Can you please tell me what is the differance in the 2?
With regards to 2.5mmsq cable which is the CSA of a copper conductor, does this mean the area of the circle as a whole? or is it the width of the conductor it is refering too?

And am I right in thinking because of pi formula! that 2.5mmsq + 2.5mmsq does not equal 5mm sq? And if so could you tell me the formula please.

This is an ongoing dispute on another forum.
Kindest regards

Soulman
[post=17743]Quoted post[/post]​
There is no obvious difference to me between mmsq and sqmm they appear to be equivalent measures of area. The constant pi does not effect the units. A circular conductor has a cross sectional area just the same as a square. Any dimensionless constant like pi just makes the units come out right.

In the US where wire diameter is measured in mils, or .001 inches, there is the concept of a "circular mil" as a unit of area. Specifically it is the area of a circle with a diameter of 0.001 inches. This makes life very easy. The area in circular mils is equal to the diameter in mils. Get it? Same number -- different units.

Now in metric cables they may have done something similar and made a subtle change in the name of the units. I don't know for sure, but it's possible.