Copper conductors size

[Gregishome]

Probaly has been on topic before here but I'll just refresh the newbies electrical curiosty here. ..

I was doing some rewiring a while back in my home that was built in 1968. I took a old metal outlet box out of the wall with the 1968 vintage old 12-2 nm/g romex in it. The #12 conductor seemed stiffer than the #12 is romex now. ..

So I got out my .001 dial vernier calipers and miked the 1968- #12 and then I miked a 2012- #12 romex conductor. ...

I found a 1968 # 14 conductor and miked it in comparison with a 2012- #14 conductor. The copper #12 and #14 gauge wire made in 1968 are both larger in diameter than the 2012 romex conductors. .

 

[pattenp]

That's the same principle where a half gallon carton if ice cream is now 1.75 quarts and cost more.

 

[larry_g]

I'll bet if you mic the 2x4's you'll find the same thing. So was the cm of the wire within tolerance of what a #12 is spec'ed to be?

lg
no neat sig line

 

[nehog]

Post the numbers. In theory the size (diameter or square mils) has not changed, at least AFAIK!

 

[djjsr]

How much of a difference is there?

Could it be that back in the 1960's most voltage was 110 and now it's 120?

 

[pop pop]

Maybe the old was USA and the new China and not relly to code?

 

[Stuart in MN]

I just checked a couple of my references; one from 1960, one from 1979, and one from today. Solid copper #12 wire has a specified diameter of 80.8 mils (.0808") in all three references. Were you measuring the bare copper, or were you including the thickness of the insulation?

 

[DekeT]

Is it possible that the old wires were not entirely copper?

 

[Gregishome]

I miked the bare copper conductor. It wasnt much difference if I recall, something like .003. Could have just been a extruder machine malfunction back in 1968 or a employee back then that was happy and said, I'll just give someone , somewhere some better wire today !

 

[eljefino]

I bet there's a manufacturing tolerance that they are now better and more consistently able to come in just a hair over the absolute minimum.