Tefzel wire. Is this normal?

[danny_galaga]

So I started having a bit of a play with the Tefzel wire I have. First impressions is that it is very stiff. That's not my concern though, see attached (click on thumbnail for full size). I was expecting it to be bright under the insulation. This is the best pic I could take. You can compare the end which is freshly cut to the side. I put a crimp on to test it and there is no extra resistance, but doesn't mean there won't be with some load on it

[Thruster88]

My experience is that it is always has a clean silver appearance

[Bruce Tuncks]

It's much stiffer than ordinary copper wire. It is possible to get colours and different thicknesses but these are not easy to buy.

I wonder just how many lives have been saved by the insistance on this wire. Cars don't have to use it.

[onetrack]

I would consider that that batch of Tefzel wire is faulty, and undesirable chemicals have been involved in the coating process.

 

All insulated plain copper wire should show bright copper upon exposure after stripping the insulation. I'd be calling the supplier and grilling them, explaining that you suspect this wire batch does not meet specifications.

The fact that there is a huge difference in the brightness between the outer and inner wires is of concern. Then again, the supplier may throw the blame back onto you, citing poor storage conditions.

 

The copper wire corrosion problem can stem from excessive fluorides in the insulation of the ETFE wire. Even NASA has had problems with it.

There are some wire manufacturers who ensure fluoride levels are low during the insulation application process.

 

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015288.pdf

 

Thruster88's experience with silvery wires may be because he is using silver-plated copper wiring in his Tefzel variety of wire. But even the silver-plated Tefzel wire variety has produced corrosion issues.

There are numerous different specs for the varieties of Tefzel wire. You can buy tin-plated Tezfel wire as well, this is a cost-saving exercise over the silver-plated variety.

Edited May 28, 2020 by onetrack

[danny_galaga]

So just an update. That is the 10 gauge wire I have. I just looked at the 18 and 22 gauge I bought at the same time and it is silver. I better contact the supplier.

[Bruce Tuncks]

Silver is way better than black! Beware the dreaded black wire corrosion.

[old man emu]

The black wires have possibly suffered water damage, as copper + hydrogen sulphide = copper sulphide.

 

Beware the dreaded black wire corrosion

Black wire corrosion is the bane of Radio Control fliers. In that scenario, the process involves connection to a power supply (battery). However, in Danny's case, the wire has not been used in a circuit, so the best reason is poor storage of the wire in wet or damp conditions. If it is due to water damage, then the black wire should not extend too far into the length, but who wants to be snipping away at a wire to get to the good stuff? You might end up with a good length of wire that is a smidge too short for the job.

 

Best thing is to do a Karen and talk to the Manager of the supply company.

[M61A1]

So I started having a bit of a play with the Tefzel wire I have. First impressions is that it is very stiff. That's not my concern though, see attached (click on thumbnail for full size). I was expecting it to be bright under the insulation. This is the best pic I could take. You can compare the end which is freshly cut to the side. I put a crimp on to test it and there is no extra resistance, but doesn't mean there won't be with some load on it[ATTACH alt=IMG_20200529_072031.jpg]53558[/ATTACH]

What does the other end look like? If the silver plated stuff has been sitting around for a while the cut end often starts to oxidise creeping up under the insulation. Sometimes you can trim it back a bit to get fresh clean wire. Sometimes not.

[danny_galaga]

It's much stiffer than ordinary copper wire. It is possible to get colours and different thicknesses but these are not easy to buy.

I wonder just how many lives have been saved by the insistance on this wire. Cars don't have to use it.

 

I'm of a mind to get a refund on the 10, and just use automotive wire for those parts and continue to use the other wire.

[Geoff_H]

Tefzel uses tin plated copper as a conductor. Tefzel is used because you can get a much lighter wiring system than PVC insulated wire. You can use a conductor that is smaller in size than with PVC insulated wire. Any copper reduction can make a sizeable weight reduction. Tefzel insulation is lighter than Teflon (although it has many similarities), so it is the lightest weight for any conductor. It is difficult to work, being slippery skinning and mechanical connection to the insulation is difficult and must be done with the highest quality crimpers. I would just use PVC insulated wire in a small aircraft.

[Yenn]

The reason for tefzel wire is to reduce the risk of fire and dangerous fumes if the wire does overheat. Use PVC if you like but be aware that it gives off noxious fumes if it burns.

[Geoff_H]

The reason for tefzel wire is to reduce the risk of fire and dangerous fumes if the wire does overheat. Use PVC if you like but be aware that it gives off noxious fumes if it burns.

Tefzel and Teflon give off more harmful smoke than PVC, if that is possible. Probabily dead either way. Believe me the only advantage of Tefzel and Teflon is weight. Significant weight reduction.

[Geoff_H]

The current carrying capacity of a conductor is limited by the maximum temperature that the insulation can take. Smaller conductors generate more heat so a higher temperature insulation can carry more current for the conductor

[danny_galaga]

Well I've been doing some wiring and I must say I actually like working with Tefzel! Because of it's stiffness, it makes for a very neat loom. I just allow it to curve naturally where it wants to. So I think I'll stick with it after all!

[Geoff_H]

The attached PDF shows the increased current carrying capacity for Teflon wire vs other insulation. Tefzel is similar to Teflon but is significantly lighter. If you were designing an electric aircraft Tefzel would contribute significantly to weight reduction.

WIREMAX-conductor-CURRENT--2- (1).pdf

[skippydiesel]

I'm of a mind to get a refund on the 10, and just use automotive wire for those parts and continue to use the other wire.

 

I am an advocate of having a dedicated earth/negative ring return circuit (in addition to whatever "chassis" earth's are in place) For this I use a quality automotive earth wire, linking all electrical components back to the battery negative.

[kgwilson]

That is a good practice except for the radio as you will end up with ground loops and unbearable noise. As comms cables are shielded they should be terminated all at one end only preferably at the radio.

[danny_galaga]

Just doing the instrument panel at the moment. Don't even have an engine ?

 

The plane is bolted Ali tubes so I knew early on I would do it earth return. On the panel is a negative bus, a positive bus and a smaller bus for the instruments to to tie to a circuit breaker. Obviously on the engine side the crankcase will be an earth. And pretty much the only other wiring is for the wingtip lights which will also be earth return.

[skippydiesel]

That is a good practice except for the radio as you will end up with ground loops and unbearable noise. As comms cables are shielded they should be terminated all at one end only preferably at the radio.

 

 

Don't have the tech knowledge to debate this but agree in general - Electrical (wiring ) loops should b avoided.

 

Don't know why I have no problem in my installation - radio great, no background noise , get compliments on clarity of transmission/ reception also "crystal". May be my earth is not a true loop but rather an alternate/complimentary parallel earth return.

[Geoff_H]

Mooney have a power earth with one connection to the airframe and at the other end of the earth strip a connection to the instrument earth bar. Instrument earth isolated from the frame. It stops earth loops and allows you to hear over the radio squark. All shield conductors MUST be only connected at one end. Same reason as above. I did a nice income getting communication systems to work that had been installed by others, usual problem was shield earthed both ends.