Tefzel wire gauges? Help a noob!

I'm to the point of running some wires to the tail strobe and elevator trim servo, and I know the correct gauges to use from Van's literature and what the manufacturers of the strobe & servo specify.

But physically, how do you determine the gauge of wire? There are some light green markings on the insulation, but they're pretty much unreadable to 51-year-old eyes. Does anyone have dimensions of the insulation diameter of various gauges that I could check with a micrometer? Or is there another method? There are multiple coils of wire included with the basic Van's kit that are unmarked.

Thanks for any input here!

Better get some glasses or a magnifying glass. The standard tefzel wire typically indicates a label idnicating awg size on the insulation. Wont take long before you will recognize the awg size by sight alone though.

The lettering is very faint and tiny on the smaller gauges?difficult to read even with magnification. You're right, though. Once I know what 22 AWG "looks" like, it will be much simpler.

Milspec wire will have a manufacturer's mark indicating the military specification, wire type, and guage.

Tin plated, copper conductor, ETFE insulated milspec wire will be marked M22759/16-(awg)

So, 20 guage wire would be marked M22759/16-20 and so on.

Like the above poster said, you might need a magnifying glass to read it.

You can read it, it usually ends in a dash number indicating the gauge (-22 for example), but it is tough. For that reason, it was worth it to buy my wire from B&C and have it spooled. Having the gauge marked on the spool removes confusion except, of course, for the inevitable odd lengths that seem to accumulate. Wire is relatively cheap, so I am becoming less of a miser for all the short pieces and my eye-strain and frustration is disappearing.

Thanks! I appreciate the responses. I think I'm good to go now.

I think I'll wrap the Van's kit wire around spools of some sort that are marked.

10x Loupe

Doug, you might as well go ahead and get yourself a 10x loupe;

http://www.edmundoptics.com/microsc...nifiers/peak-transparent-base-magnifiers/1862

I've had one for more than 20 years and it saw nearly constant use on the job. In fact, one is needed in order to 'properly' comply with SAIB HQ-14-16:

http://www.rotor.com/rotornews/April14/HQ-14-16.pdf

One caveat, though. Don't look at anything with that loupe you don't need to look at. To the naked eye an object you've just finished fabricating can look smooth and regular and perfectly fine, but at 10x it suddenly resembles the surface of the moon.

Thanks, John. Ah, the loupe?.I've used one to look at thousands of transparencies on a light table, back when cameras used what was called "film."

Use your micrometer instead

No loupes needed...

Assuming you have the correct Mil 22759/16 wire, measure the OD and look it up on the chart here -

http://www.awcwire.com/productspec.aspx?id=mil-w-22759/16

az_gila said:

No loupes needed...

Assuming you have the correct Mil 22759/16 wire, measure the OD and look it up on the chart here -

http://www.awcwire.com/productspec.aspx?id=mil-w-22759/16

Click to expand...

Perfect, Gil. That will erase all doubt.

I might make a "gauge gauge" with max O.D. values drilled in a piece of aluminum.

Wire Gage and Connectors

May I make a suggestion? You will mainly use three sizes of connectors:

Red = 22-18 gage
Blue = 16-14 gage
Yellow = 12-10 gage

With the exception of the high-current draw items, I recommend you purchase just three gages of wire - 18, 14, and 10. (You will need lengths of gage 6 or gage 4 [maybe 2?] but they will require specific and larger connectors or you may need 22 gage for signal in D-sub connector but that's not what I'm referring to here.)

If an electrical load requires, for instance, a 16 gage wire (that would go in a blue connector) what's the harm in increasing it to 14 gage? It's still in the blue connector.

The reason I make this recommendation is that I previously calculated and purchased lengths of wire in the exact gages that I thought I'd need (plus a little more for "just in case"). Now I've got varying length coils of SEVEN different gages of wire when I really only needed three!

Just a thought....

The crew has answered the gage question pretty well. Some smaller wire is hard to read even with magnifiers, the color contrast is just BAD, and I use the dial caliper for that.

If it is really to small to read, then you might invest in a magnifier with a headband. I use mine constantly in wiring, for selecting wire, stripping and crimping d-sub pins on fine wire. Being able to see fine detail helps drastically in such things as rivet removal too.

I made a wire reference board when I built my plane. I took a short piece of wire of each gauge that I was using and stripped a bit of insulation from each one. I taped the pieces of wire to some cardboard and labeled them with their gauge number. I only had to struggle reading the numbers one time while I was making the board.

After a while I was able to eyeball the correct size most of the time.


If you haven't figured it out already, get yourself some high quality wire strippers. Hardware store quality strippers are not up to the job when it come to Tefzel insulation.