Identifying Existing Electrical Conductors, Measuring Tool

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Shujinko

Shujinko

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I have a project where I have to survey an existing site and identify all conductor and conduit sizes and put them on an as-built riser diagram. The issue is that none of the conductors have any identification for size on the insulation since the building is old. Is there any way that I can easily identify the exact conductor size? Is there a measuring device that could measure this quickly and accurately? How about for conduit sizes? Thanks.
 
short of a handheld xray device, and everything is accessible, maybe calipers and/or a set of made go/no-go gauges? how old is the install?

once you get a reference for actual size of one wire (copper, and then with insulation), you can use that to "size" the other wires measured.
 
Shujinko said:
I have a project where I have to survey an existing site and identify all conductor and conduit sizes and put them on an as-built riser diagram. The issue is that none of the conductors have any identification for size on the insulation since the building is old. Is there any way that I can easily identify the exact conductor size? Is there a measuring device that could measure this quickly and accurately? How about for conduit sizes? Thanks.
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Just to clarify I am asking about a tool or device that will quickly measure the diameter of the conductor.
 
Shujinko said:
Just to clarify I am asking about a tool or device that will quickly measure the diameter of the conductor.
Click to expand...
If you can’t find an old Sparky of the same vintage as the building, you’re stuck with a digital micrometer and insulated-conductor tables in chapter 9.
 
FionaZuppa said:
short of a handheld xray device, and everything is accessible, maybe calipers and/or a set of made go/no-go gauges? how old is the install?

once you get a reference for actual size of one wire (copper, and then with insulation), you can use that to "size" the other wires measured.
Click to expand...

The install is 30 years old. Not sure what is installed maybe XHHW or THHN/THWN? I am possibly looking to make some molds for each conductor size based on the conductor diameters in NEC Chapter 9, Table 5. A caliper is a pretty good idea too. I'll probably look into getting one. Any good ideas for a good & cost effective caliper for this type of task?
 
Shujinko said:
The install is 30 years old. Not sure what is installed maybe XHHW or THHN/THWN? I am possibly looking to make some molds for each conductor size based on the conductor diameters in NEC Chapter 9, Table 5. A caliper is a pretty good idea too. I'll probably look into getting one. Any good ideas for a good & cost effective caliper for this type of task?
Click to expand...
You can get inexpensive plastic vernier calipers designed for student use in labs and shop. They will not last long in the bottom of a tool box, but they are nonconductive!
 
GoldDigger said:
You can get inexpensive plastic vernier calipers designed for student use in labs and shop. They will not last long in the bottom of a tool box, but they are nonconductive!
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harbor freight has good ones, in a case, will last in your truck, and cost less than lunch does.

its the insulation part that will be tough. ~30yrs ago, i wonder if wires of different gauges used the same insulating thickness even if it was all say 300v rated.

something like this might be handy. if you have std insulating thickness (know it) you can offset the gauge measurement accordingly to get the real copper wire size.
https://www.youtube.com/watch?v=8jGjlKjF2vI

MYC_950-202.jpg
 
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30 years ago conductors had all sorts of marking to identify size & type -- now go back 70 -80 years -- hire an old cranky retired electrician he'd probably know by sight --:lol:
 
FionaZuppa said:
harbor freight has good ones, in a case, will last in your truck, and cost less than lunch does.

its the insulation part that will be tough. ~30yrs ago, i wonder if wires of different gauges used the same insulating thickness even if it was all say 300v rated.

something like this might be handy. if you have std insulating thickness (know it) you can offset the gauge measurement accordingly to get the real copper wire size.
https://www.youtube.com/watch?v=8jGjlKjF2vI

MYC_950-202.jpg
Click to expand...

Nice tool but you have to be able to pass wire thru it from top or bottom to check its gauge.

Digger's suggestion of plastic calipers is a great one and I think you can get a cheap pair for ~$10 or so.
 
JFletcher said:
Nice tool but you have to be able to pass wire thru it from top or bottom to check its gauge.

Digger's suggestion of plastic calipers is a great one and I think you can get a cheap pair for ~$10 or so.
Click to expand...

no, the round holes are not the size, the slot is. its why i also gave the yoo tube link ;)
 
Will all the wiring in the building be from the same installation? Something that old may very well contain different insulation types with some #14 appearing like #12 (for one example) until you strip it, or will you always be inspecting at the terminations?
 
Use a caliper and measure the outer diameter of the stripped copper and then refer to the NEC for conductor properties and kcmils


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