Use of #3AWG Not Common
- Thread starter W6SJK
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
We use it all of the time but we are dealing with large supply houses and wire vendors. To me using something larger is often a waste of money especially given the current cost of copper.
I never had a problem getting #3 from my suppliers, I don't know about big box stores though.
Roger
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I have had installers replace #3 with #2 aluminum conductors in my PV system designs because they could not get #3.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
There are certain sizes we don't generally use and #3 is one of them. We can get it, but we don't need much of it and the guy in charge does not want to have a bunch of it left over that can't be used for something else so he usually changes it to #2 unless we need a whole lot of it for a single project which just does not happen. Th ampacity range that #3 is most suited for just does not seem to come up in our designs real often.
ptonsparky
Tom
- Occupation
- EC - retired
We have been able to get it in cut lengths from our suppliers in the past, if needed, but we were more likely to have leftover pieces of 4 or 2.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I would say #3 is a commonly needed size as it is 100 amps for other than residential services and feeders.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
That's the reason we use it. There are many 100 amp circuits and feeders in commercial work.
For what its worth, I too had heard of this rumor a long time ago. Might just be one of those things that has been passed person to person and become fact, when in reality it is as normal or accessible as any other size.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I have encountered it; see post #5.
due to recent supply chain issues or just normal course of business?
drcampbell
Senior Member
- Location
- The Motor City, Michigan USA
- Occupation
- Registered Professional Engineer
Sure, I'll just ask for 95 mm2 here in the Colonies. That'll assure prompt service!
I was going to make a remark about Americans, the metric system, and avoiding it like the plague. But as it turns out, that's something we don't do very well, either. (more than one third of adults in Michigan haven't had their first covid vaccination yet)
Xenophobia and bad education are so popular here -- not to mention indifference to specifications -- that if you were to walk into a lumberyard and say that you need a sheet of plywood between 3 and 30 mm thick, the response would be "We don't carry no metric sizes.".
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Normal. It was happening years ago before the pandemic.
Yes, I was trying to envisage 3AWG. For metric units it is, I think, simpler. The larger the conductor is the just the actual physical size. I think the whole concept is just simpler with metric. I know when I was at school, a very long time ago, we had Imperial with feet, inches, pounds, miles etc. Later when I was a secondary school we got introduced to metric. The rest is history.
GeorgeB
ElectroHydraulics engineer (retired)
- Location
- Greenville SC
- Occupation
- Retired
You use newtons for force/weight and km/hr for speed, correct? (just teasing; we have our mishmash of units here too)
It isn't a mishmash actually.
" the force that would give a mass of one kilogram an acceleration of one metre per second per second,"
Better than pounds and ounces.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Or slugs.
kwired
Electron manager
- Location
- NE Nebraska
My guess, if you purchasing from big box or a supply house that primarily sells to people doing residential projects, there isn't much demand for #3 copper and they likely don't stock it or have limited stock. 100 amp services or feeders to a dwelling unit can use #4 instead of #3.
You probably will also find #2 aluminum is also common for such places to have but #1 might not be - for same reasons.
You probably will also find #2 aluminum is also common for such places to have but #1 might not be - for same reasons.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
I don't do a lot of commercial work, so I wouldn't have a common use for #3
But 3 years ago I wired a restaurant that had 2 - 100 amp subpanels, and I got #3 from a supply house readily available.
In fact, I still had some of the scrap laying around, and used it on 2 residential subpanels in the last week or so.
But 3 years ago I wired a restaurant that had 2 - 100 amp subpanels, and I got #3 from a supply house readily available.
In fact, I still had some of the scrap laying around, and used it on 2 residential subpanels in the last week or so.
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