Larger conductors save money.

[mbrooke]

Electrical loads are decreasing esp with LED lighting. Non dwelling units typically have services 30% larger than needed as the lighting loads are 3 w sq ft and energy codes are perhaps .5 w sq ft.

CDAs job is to sell copper, they were behind the rooftop derating scheme, that the code writers didn't know the difference between raceway and conduit...

30% try? Try 2 to 3 times larger.

 

[wwhitney]

however, their assumptions given...

"[FONT=&quot]Estimated Loss (at 15 amp load and 40°C, and 37°C, respective conductor temps.)"

are we gonna have 3 deg. C change in wire over ONE wire size?
is the line loss gonna be what they say it is, really?

[/FONT]

77 W

48 W

c'mon, EE's.... help me here. how did they get here, even plausibly?

I'm not an EE, and I don't know how to calculate the equilibrium conductor temperature, but can say this:

With the information given (100 feet of 2 conductors, 77/48 W power loss, 15 amp current, and #12/#10 conductors), we can calculate the implied resistance/1000 ft via P=I²R, or R = P/I²:

For the #12, R/kft = (1000 ft / 200 ft) * (77 W)/(15 A)² = 1.7 ohms/kft
For the #10, R/kft = (1000 ft / 200 ft) * (48 W)/(15 A)² = 1.1 ohms/kft

Those numbers match the Table 9 Effective Z for 0.85 PF.

So power loss figures seem on the face of them to be reasonable. Of course, that is for a 15A, 24/7 continuous load.

Cheers, Wayne

 

[don_resqcapt19]

For equipment that runs at or near full load 24/7, you can often get a 2-3 year payback by increasing the conductor one size, assuming that does not also require a larger conduit.

 

[electrofelon]

Im still eagerly waiting for the article from copper.org: "aluminum wire saves money"

 

[peter d]

Im still eagerly waiting for the article from copper.org: "aluminum wire saves money"

:thumbsup::lol:

 

[peter d]

I think we can safely disregard these findings for just about all residential settings.