Recently, I was questioned as to what type of wire one should use to replace and/or rewire a diesel locomotive. One school of thought is to use DLO for the high-voltage cabling http://www.southwire.com/products/DLODi ... bleoem.htm which is oil resistant and Exane http://www.electrowire.com/products/exane/ for the low-voltage wires. This school of thought is based on the fact that these materials are used by locomotive manufacturers and is top-of-the-line material that will outlast anyone alive today.

Another school of thought is to use welding cable https://www.wireandcableyourway.com/Welding-Cable/ for the high-voltage cable and THHN http://www.southwire.com/products/oem-t ... 75-t90.htm for the low-voltage wire. This school of thought is based on the fact that THHN is stranded so it's just as good as what's being replaced and the welding cable is, well, subject to similar conditions found on locomotives.

Just wondering what others are using.
Thanks,
Rob

We need someone who actually as experience specifying this stuff to comment, but I would be leery of THHN. THHN is building wire. Even the stranded version is not particularity vibration resistant because of the lower count of bigger strands. It is made for ease of pulling, but intended for a stationary application.

I would be inclined to be looking for MTW, Machine Tool Wire. It has a higher count of smaller strands, for increased flexibility and resistance to vibration causing the strands to fracture.

Brief discussion here:

https://awcwire.wordpress.com/tag/mtw-vs-thhn/

All our re-wires use DLO for high voltage power cabling and Exane for everything on the low voltage side. Some exceptions on the high voltage side are all wheel slip feeds that are under frame (typically #6 wire) are run in Exane.

Just as important to the job is the quality of the crimp connectors and crimping tool used and the wire labels applied. I see more failures that range from no start/no loads to cabinet fires on account of poor crimping or worn out push ons.

It is my opinion that THHN/THWN does not have the flexibility for long term success on a locomotive. Over the years I have seen some pretty good cabinet fires that Exane wire survived in remarkably unscathed condition generally requiring just a cleaning before going back into service.

When we were re-wiring our (Juniata Terminal)1969/1973 built SW1500's the material cost of the wire was fairly insignificant as related to the costs associated with rebuilt switchgear and force account labor.

Eric Levin

Another brand is Polyrad XT from General cable, very similar to Exane.



I'd argue that school of thought is way too far off to be useful, even dangerous. Stranded wire is definitely NOT all the same. Since I'm working on car wiring at the moment I'll compare #14 and 4/0 sizes.

The #14 THHN you linked shows rated at 15 amps @ 90C, is un-coated copper, is sheathed in PVC and is 19 strand across the listed sizes of 6AWG - 14AWG. Polyrad XT is rated at 39 amps @110C (probably around 36 at 90C), is tinned copper, sheathed in cross-linked Polyolefin and increased stranding above 12 AWG.

The 600V 4/0 welding cable you linked shows rated at 310 amps @ 90C, is uncoated copper, sheathed in EPDM and is stranded 2054/30. Polyrad XT (2000V standard) is rated 446 amps @110C (about 405 @ 90C), is tinned copper, sheathed in cross-linked Polyolefin with 550/24 stranding.

The Exane/Polyrad is also oil and chemical resistant and additionally has enhanced flame resistance and low smoke toxicity. It will hold up to flash fires fairly well - I've seen some smoked and not damaged other than soot. The tinned copper strands will resist corrosion and wear within the cable and maintain electrical properties in the long term far better than un-tinned. PVC will burn readily and both PVC and EPDM will produce very toxic/dense smoke, and much earlier in a fire than the better rated stuff. The ampacity of the Exane/Polyrad is far better than the same size THHN, more than double at 14AWG.

The DLO looks somewhat similar to the Exane/Polyrad, with different stranding and insulation but similar ampacity, and is listed for traction motor leads. They don't list anything for flame test specs, so I'd keep that to outside use unless they can provide more information. I've only seen it as motor leads and don't know about it's durability first hand.

You'd be toying with a host of problems using the second, 'cheap' school of thought, not the least of which would be shorter lifespan, higher maintenance/replacement costs long term, and safety hazards to equipment and personnel using the inferior materials. IDK what you're rewiring, and cheaper might work some places, but....

About 8 years ago when we started to trace the wires in our S4 so we could rewire her, I spent time talking to a couple of locomotive rebuilders and here is what they suggested for wires.

Low voltage should be the Exane or equivilent, if it is only in the cabinet and is going to be wrapped to the supports than THHN can be used, but not recommended.

For any wire heavier than 8 gauge the conductor must be single twist like welding cables, not the common multi-core style. If you look at the end of the wire when it is cut, common heavy wire will have groups of wires twisted together and the group of bundles will be twisted, where as what you want is for the whole mass to twist as a group, also the single core will usually have thinner conductors in the cable. This gives you better conductivity and better flexibility. If you bend the multi-strands sharply, you will break conductors.

Our SW-8 which was rebuilt by NRE (National Railway Equipment) before the previous owner purchased her. has Exane wire for the regular circuits, I forget what they used for the heavier runs.

Rich C.

I took some old Alco switchers apart that had replacement wire in the from General Electric. This was the heavy cabling that run from the main generator to the reverser. It was GE part number 5158215. It was all in such good condition that I saved it for future use.

GE also makes wiring for the low voltage.

Exane is very good and they also make a special wiring to use around resisters where it get very hot. It is "Orange" in color and is a little fuzzy. It is 14 AWG 91/26 with a #SE 1927 on it.

I also removed some heavy cabling from the reverser to the traction motors that was "Royal Diesel Locomotive" 444 MCM ( 1100 #24 ) 1 KV P-122-67 MSHA. This was also a very good wire/cable. I have seen this for sale before on Ebay.

Absolutely, NEVER use THHN wire in a locomotive. The crimps will loosen over time and drive you absolutely crazy trying to troubleshoot the issues as they develop and disappear and come back randomly. I cursed and swore I would kill the individual if I knew who it was that installed that crap, and without any labels. Unfortunately it was the owner of the company I was working for at the time and he was standing next to me. It was an interesting ride home in the company truck.

Mike Tillger

Thanks to all for the responses. One can hope some will read this as there are at least two (2) different locomotive "rebuilders" out there who wire with the THHN and welding cable route. Caveat Emptor when dealing such firms.

The comments concerning proper crimping for the ends is spot-on. One could add that using stainless steel hardware for attaching said crimps isn't always the best material either. It can gall and make disassembly rather complicated.

Rob

look at the old fittings you are taking out, and consider how old they are. What methods did the oldest ones use?