Can you guys give me tips on how to tell what the wire size is without reading labels? I come across so many wires without labels and sometimes it's hard to see the labels. When I meet with electricians on site, they automatically know the wire size by just looking at it which is impressive to me.
Identifying wire sizes without labels
- Thread starter Tainted
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
They make plastic gauges that you can use to determine the conductor size. Or measure the OD and look it up.
I am having a hard time finding ones that are up to 500kcmils. Do these plastic guages account for insulation around the wires?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
It's similar to being able to recognize screw threads by sight. Practice and experience.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Many also can just look at a hex head bolt/screw and automatically know what size wrench/socket they need to drive it, at least within certain size limitations anyway. You see something nearly everyday and this sort of thing just becomes natural.
The insulation on the wire can sometimes make it a little deceiving just looking at it, but if I can just touch it, even have the ability to bend it a little I usually can tell better when it is questionable.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yeah that works until they threw in those metric screws with the light fixtures. lol
I see. As an engineer I never installed anything and don't even know how I could train myself to be proficient in this skill without being an electrician.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I was good with SAE hex heads even when I was still in my teens. Metric heads always threw me off as I didn't run into them as often as now. But anymore I often know just looking at it whether it needs a SAE or a metric wrench/socket and usually what size.
David Castor
Senior Member
- Location
- Washington, USA
- Occupation
- Electrical Engineer
You're assuming they are actually right.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
For those with money to spare:
BURNDY Caliper-Style Wire Thickness Gauge
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If you are trying to guess the wire size then I would measure the bare copper or aluminum
measuring the bare copper ends or aluminum end require power shutdown (unless you're not grounded if you know what I mean but that's too risky for me lol)
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
The Wire Mike caliper has different scales for different insulations. An unskilled operator might have some problems identifying insulation types but for larger conductors it is less of an issue.
I am the unskilled operator
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If you know insulation type you still can determine conductor size off that dimension.
Though you also might need to realize whether you dealing with normal stranded or compact stranded conductors as well.
JoeStillman
Senior Member
- Location
- West Chester, PA
A trick I learned from an older engineer was to wrap a little slip of paper around the wire and mark the circumference, then measure between the marks and divide by pi.
- Status