DLO Locomotive Cable in the NEC

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rbarnett's picture
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Joined: 2014-03-04

It is not uncommon to hear of DLO Locomotive cable being used in applications where flexibility is needed. DLO cable is pretty finely stranded and works well. However, DLO is not in NEC Article 400 on Cables or in Sec. 310.104 Conductor Applications and Insulations. Or is it and I'm missing something? How do you size and then apply this cable in the field?

skd76's picture
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Joined: 2013-09-11

Locomotive (DLO) cables aren't addressed by the NEC. Fine wire termination apparatus is newly addressed by UL and is now somewhat available. I have utilized and I've approved DLO in big motor applications. Often when a motor terminal compartment is way smaller than the bending radius needed for standard conductors. The DLO manufacturer will provide ampacity tables and the AHJ may approve - when/if it is a sensible application.

rbarnett's picture
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Joined: 2014-03-04

Makes sense. I found some DLO cable that manufacturer says has RHH insulation and thought maybe I could take that to the tables since RHH is there. But Article 400 makes it pretty clear if it's a cable and not in the Code then it's up to the AHJ. Obviously, the manufacturer's info makes the best resource.

dpiper's picture
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Joined: 2014-05-28

If using manufacturer's ampacity tables be sure that their ampacities are based on your installation methods (i.e., NEC Art. 392, IEEE 45, API 14, etc.). Also, confirm what the temperature rating ampacities are based on. If temperatures are higher than what your terminations are rated for then you must derate the cable to the correct temperature.

Paul Abernathy's picture
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Joined: 2012-12-21

@rbarnett -

Hello my friend. Just figured I would say that in many cases where a manufacturer (and I work for one) produces a product with multiple insulation classes (RHH,RHW-2, USE, etc.) they are indeed evaluated and listed for that specific choice of class you wish to use the conductor for. All the requirements for that such class of insulation are required to be observed but just wanted to indeed state that manufacturers will produce dual and triple rated conductors all the time in an effort to give a broad use to the products.

With that said we (Encore Wire) do not produce DLO but we do produce products that are for example USE/RHW-2/RHH rated and even URD Cable with the same triple ratings so now penetrate into the structure where much of older URD was utility grade and not fire retardant rated....those days are changing.

EPHoet's picture
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Joined: 2014-12-16

I've used DLO cable for an MG set application (up to 440 Hz) as well as a VFD motor cable (also up to 400 Hz) to a movable test stand [373.7 kcmil]. It has worked well. Now considering paralleled 4/0 cables to carry more current from an upgraded VFD that will be operating at 690V instead of 480V. Unfortunately, standard U.S. NEMA wiring has little to offer above 600V, short of 2kV rated cable like DLO.

rbarnett's picture
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Joined: 2014-03-04

All good comments. Thanks for the input. Hey Paul, very interesting. I nominate you to write an EC&M article on the basics of cable insulation! I would love to read it and certainly need to know more!

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