Has anyone tried using Calipers for determining wire sizes? I find that manipulating cables and moving your face close to cables in order to read the markings on insulation could be extremely dangerous especially when performing the studies for the first time since the equipment is not yet labeled.

My thought is to use the insulation type in conjunction with an OD measurement in order to accurately determine conductor sizes without having to rely on printed measurements. Does anyone do this or know if there's specific equipment meant to do this? I was planning to use a set of generic composite calipers to take measurements.

something like this: https://www.amazon.com/gp/product/B073N ... _qh_dp_hza

You can get plastic calipers. I've done this. Not above 600 V but I've done this. Not that you should have access to cables above 600 V in the first place.

Measuring the cable is one thing and pretty reliable but when it comes to the insulation.....there is a very wide variation in sizing so it doesn't work all that well and there is a lot of guess work involved. Think for instance just the differences between THWN and XHHW-2. ICEA standards definitely put limits on OD of the uninsulated cables and on minimum insulation thicknesses of the cables but beyond that it's wide open.

If you've ever had to order cord grips you'll know what I mean. For smaller sizes the range of dimensions for CGB's (cable glands) makes it pretty easy but when you get up to sizes where it matters, the size ranges on CGB's are so tight that I find that practically I have to buy the cable first and then order cable glands.

I use a DSLR and take a photograph of the wire, fuse, breaker, etc. With a high resolution digital photograph you can zoom in and read very small print. Most software for digital photo editing will help you by increasing the contrast to help make out faded text.

I use a long lens to photograph of fuses at the top of poles and can read the type, ratings, etc. Not only does it help with finding out what you have, but also provides a record for future reference.

Roy Dutcher
Electric Safety, Inc.

We will also make of use of a hi res digital camera when doing data collection to record any unusual setups, trip unit settings, etc. We generally depend on our electrician to determine the wire size and insulation which in the majority of cases he is able to do.

I am curious to know how photographing fuses at the top of poles works. For the majority of distribution fuses (cutouts) the max fuse size is on the outside of the fuse holder tube but the actual fuse size is printed on the button of the fuse inside the tube. I have done what you state on larger substation type fuses (34.5kv, 46kv, etc) where the size and speed is on a label on the fuse tube.

Someone smarter than me needs to write an app for this. I know there are apps that take measurements. Take a pic of the cable and enter the most likely insulation type and it spits out the gauge.

The fuse size is visible on indoor fuses but on outdoor fuses quite often it is unreadable after a while.

It would be hard to write a measurement app because you'd have to hold the phone in a very particular way to get a reading from a photo and you need sub millimeter accuracy on smaller wires with the general applications.

There are some very inexpensive 3D cameras on the market though that use structured light to make measurements in the right range which could theoretically do this quite easily using the captured 3D data.

The easiest way to get cable sizes is to read the writing on the cable. It takes a while hunting around to find it sometimes and sometimes it is so faded that it can't be done. I have to do it all the time on installations.