Larger conductors save money.

[packersparky]

I'd like people's opinions on this article.

http://www.copper.org/environment/s...mXRYfXo_wpAvToXGGR0rZAM#.XQwd0-9AgAs.facebook

 

[Little Bill]

IMO, the writer put just enough truth in there for it to sound good. But mix in other "garbage" and you get a copper wire mfg pushing their product as "bigger/more is better"!
The NEC already has very conservative wire sizes and if you go above that, you are not saving anything by oversizing wire needlessly. There are instances where it would be better to upsize, but generally speaking, it's just a sales pitch!
Try landing #10 AWG conductors on a house full of 15/20A duplexes & switches!
You would also go over on box fill in a hurry, such as a multigang switch box.

 

[tom baker]

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...

 

[Fulthrotl]

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...

this week, i was involved with lighting compliance for a large apartment building for T24 compliance.

hallways normally need partially off lighting, and over 10k sq ft of space, demand response for load shed.

unless.... it's less than .5 watts per square foot. no load shed or partially off controls. let them burn.

how much lighting were in these 6' wide by endless hallways? one 10 watt led puck light every 12 feet.
we are putting the entire thing on a vive system, so that we can have local controls without cutting
in wall switches.

that is 443 light fixtures on one 20 amp circuit, using 80% capacity.
just a little bit over a mile of hallway. one circuit.

i think we can hold off on the bus duct for now.

oh, yeah, by the way.... we will trim the lights to about 90% to increase their life.
in case you thought they were too bright...

 

[Cow]

that is 443 light fixtures on one 20 amp circuit, using 80% capacity.
just a little bit over a mile of hallway. one circuit.

I can only think, if we had 443 fixtures on one circuit, and one has a short in it and trips the breaker......how many man hours will it take to find it.....?:blink:

 

[ggunn]

I'd like people's opinions on this article.

http://www.copper.org/environment/s...mXRYfXo_wpAvToXGGR0rZAM#.XQwd0-9AgAs.facebook

Consider the source. It sounds like a pitch to sell more copper.

 

[electrofelon]

I must have missed the part in there, with all the talk of saving money, where they say "using aluminum conductors can offer a big savings over copper." :lol:

 

[Jraef]

By extension of their logic if I wire up my 15A circuits with 500kCMil, I get free electricity!

 

[480sparky]

I'd prefer to see a wide variety of ROI's. Different lengths, different wire sizes, different loads, different wiring methods......

I'm sure they cherry-picked their examples.

 

[Coppersmith]

I can only think, if we had 443 fixtures on one circuit, and one has a short in it and trips the breaker......how many man hours will it take to find it.....?:blink:

Assuming all the wiring is accessible you would have to disconnect the string of lights at eight points maximum to find the bad light/connection using a binary search method.

 

[LarryFine]

Assuming all the wiring is accessible you would have to disconnect the string of lights at eight points maximum to find the bad light/connection using a binary search method.

And how would you carry out such a divide-and-conquer method? Play Russian Roulette with the breaker?

 

[480sparky]

And how would you carry out such a divide-and-conquer method? Play Russian Roulette with the breaker?

Use a dummy load at the breaker. Disconnect the circuit from the breaker and insert the load in series with the circuit.

 

[Little Bill]

And how would you carry out such a divide-and-conquer method? Play Russian Roulette with the breaker?

I don't know about any binary method, but I would put a load such as a pigtail socket with bulb in series with the breaker. Then I would go look for the light that wasn't working. Do I win anything?
That's assuming the light with the short blew either the bulb or driver if LED.

 

[LarryFine]

Use a dummy load at the breaker. Disconnect the circuit from the breaker and insert the load in series with the circuit.

I don't know about any binary method, but I would put a load such as a pigtail socket with bulb in series with the breaker.

Yes, I've been doing this for many years with a high-wattage bulb, acting as an indicating current limiter, even screwing bulbs into plug-fuse panels. I once used a shop-vac so I could hear it from the trouble area.

But we're talking about a great number of lights in parallel that can't be unplugged during trouble-shooting, so it's going to be a very low impedance compared to the bulb on both halves of the chosen dividing point.

Then I would go look for the light that wasn't working. Do I win anything?
That's assuming the light with the short blew either the bulb or driver if LED.

There would be an entire group of lights not working, until you pare (pair ) it down. I'm not sure any of the lights would light, unless you use a really huge light bulb p) or something like a 1500 watt heater.


Added: I just realized that you'd have to drag a cord around the building with you to energize circuit halves and quarters and eighths and . . . and . . . :happysad:

 

[Coppersmith]

And how would you carry out such a divide-and-conquer method? Play Russian Roulette with the breaker?

1) Find the midpoint of the string of lights.
2) Disconnect the two halves.
3) Tell your helper to flip on the breaker.
4) If the breaker trips, the short is in the half closest to the panel, if it does not trip, it's the other half.
5) Tell your helper to turn the breaker off.
6) Reconnect the string and move to the midpoint of the half that has the short.
7) Repeat from item 2 until the short is located. A maximum of 8 tries (and breaker trips) will locate the short in 443 lights. I'll let Gar describe the math.

If you don't like having the breaker trip, you can disconnect the hot from the breaker and measure resistance on the circuit with your meter.

 

[LarryFine]

So, yes, Russian Roulette.

 

[packersparky]

This thread was about the validity of saving money using larger conductors sizes, and is now has morphed into something totally foreign to that. Mods, please close this thread.

Edit to add: I am glad I am not Coppersmiths helper.

 

[LarryFine]

That's a little harsh; threads often "morph" here. If the conversation leads down a tangent, it's not necessarily bad.

 

[Little Bill]

Last Call

Last Call

Let's see if we can steer this thing back onto the road and the course it was intended for!

 

[Fulthrotl]

Let's see if we can steer this thing back onto the road and the course it was intended for!

ok. larger conductors save money.....

if you make them out of aluminum, yes.
otherwise, no.

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

[FONT=&quot]
c'mon, EE's.... help me here. how did they get here, even plausibly?

[/FONT]