Not using certain wire sizes

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zam

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The senior engineering staff at my job has asked us not to use #3, #2/0 and 400 mcm wire sizes when sizing the wires. I asked them for a reason why not, but they did not have a convincing answer. Any feedback from the forum would be appreciated. Thank you.
 
zam said:
The senior engineering staff at my job has asked us not to use #3, #2/0 and 400 mcm wire sizes when sizing the wires. I asked them for a reason why not, but they did not have a convincing answer. Any feedback from the forum would be appreciated. Thank you.
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#3AWG and 400kCMIL, are usually not a stock item; the #2/0 is usually readily available.
 
Those are atypical sizes from my experience, except for #2/0 and I've never specified #400kCmil so I'm unsure of its availability. Not exactly a convincing argument, but will be following this thread for other's experiences with those conductor sizes.
 
My guess would be availability from wherever they get the wire. I'm also guessing that if they are not allowing those wire sizes and you happen to need one, ordering the next size up is standard practice.

What reasons, however unsatisfactory, did they give you?
 
roger said:
In NC it was too, now that I'm back in FL it's special order, go figure. :rant:

Roger
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We do a lot of large high rise apartment buildings which typically have a 100 amp panel within the apartment. Using #3 over #2 saves some money on each apartment, multiply those savings by 700-800 and you have some nice money in your pocket.
 
infinity said:
We do a lot of large high rise apartment buildings which typically have a 100 amp panel within the apartment. Using #3 over #2 saves some money on each apartment, multiply those savings by 700-800 and you have some nice money in your pocket.
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I agree and don't understand why it's not a stock item here. In the Asheville area you could walk into any supply house counter and buy it, large orders were never a problem either.

Roger
 
Dale001289 said:
#3AWG and 400kCMIL, are usually not a stock item; the #2/0 is usually readily available.
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yep. having said that, it is not real hard to order it but for us we normally don't use a whole lot of it at a time so it is easier just not to order stuff that is not real easy to come by. If I needed a few thousand feet of #3 it would be worth it, since it is about 25 cents a foot cheaper than #2.

For us too, there are certain sizes we almost never run across, just because it works out that way. #3 is one of those sizes. #3 is what you would use on a 60 HP 460V motor. I can't remember ever seeing a 60 HP motor. So it is better to just get #2 and not have something left laying around that we won't use up in the next 5 years.
 
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I had a boss at a previous engineering company that told us never to show 1-1/4" conduit in a design. It was either 1" or 1-1/2" for him. He never said why. I imagined it had to do with the availability of the 1-1/4" in the supply stores. But it may have been one of those "that is what I was taught and that is what I am teaching you" things (the "ham bone story," if you have heard of that).
 
roger said:
I agree and don't understand why it's not a stock item here. In the Asheville area you could walk into any supply house counter and buy it, large orders were never a problem either.

Roger
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I would hazard a guess that it's primarily an issue of how much of what size wire the local supply houses sell and therefore stock.
 
I don't see why a supply house not stocking #3 would be a reason for an engineer to state it can't be used:?

My supply houses typically stock #3. But at same time if I went in and wanted 10,000 feet they may not have that much on hand but can possibly have some sent from another branch and have it the next day.
 
kwired said:
I don't see why a supply house not stocking #3 would be a reason for an engineer to state it can't be used:?

My supply houses typically stock #3. But at same time if I went in and wanted 10,000 feet they may not have that much on hand but can possibly have some sent from another branch and have it the next day.
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Well, as an engineer I don't see any reason not to specify a #3 when it's what the circuit calls for if availability were not the issue.
 
infinity said:
For us #3 AWG is a common size for 100 amps and it is readily available.
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infinity said:
We do a lot of large high rise apartment buildings which typically have a 100 amp panel within the apartment. Using #3 over #2 saves some money on each apartment, multiply those savings by 700-800 and you have some nice money in your pocket.
Click to expand...

I was doing a 100 amp subpanel the other day and thought I had enough wire on the truck, but did not so off to Home Depot I ran. Code book said I could use #3, but I just assumed it was a non-stock item. Instead I asked them to cut 30 feet of #2. A second after the wire was cut I noticed the reel of #3 sitting right next to the #2 reel. 30 cents cheaper per foot and a lot easier to squeeze into a crowded main panel. Ouch!
 
Coppersmith said:
I was doing a 100 amp subpanel the other day and thought I had enough wire on the truck, but did not so off to Home Depot I ran. Code book said I could use #3, but I just assumed it was a non-stock item. Instead I asked them to cut 30 feet of #2. A second after the wire was cut I noticed the reel of #3 sitting right next to the #2 reel. 30 cents cheaper per foot and a lot easier to squeeze into a crowded main panel. Ouch!
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Yup as an installer I would prefer #3 over #2 even if I'm not paying for it. :)
 
charlie b said:
I had a boss at a previous engineering company that told us never to show 1-1/4" conduit in a design. It was either 1" or 1-1/2" for him. He never said why. I imagined it had to do with the availability of the 1-1/4" in the supply stores. But it may have been one of those "that is what I was taught and that is what I am teaching you" things (the " if you have heard of that).
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I don't wish to take this off topic but "ham bone story,".........?
 
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