DLO Cable

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753MTE

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I'm installing a 1200A 3Phase 4 Wire 120/208V service. I'm feeding the CT cabinet with 3 sets of 600mcm from the pad mount transformer. The problem that I'm having is getting the MDP to line up in a reasonable manner, on the other side of the wall with the CT cabinet. The bends in the wire are going to be very difficult to make. I'll have 16 600mcm conductors all twisted up in a very small area, plus the 16 conductors coming into the CT's line side! So, I've been doing some research and I came across a single conductor cable, DLO. The cable is about 2x's as much/foot, but its worth the aggravation. The ampacity rating for DLO 646.4mcm @ 75 C is 730A. So now I believe that I can go from 3 sets to 2 parallel sets. Additionally, I think I can move down to the next size, which is DLO 535.3mcm (645A @ 75 C). I don't think that I have to do any corrections for 3 or more current carrying conductors in a conduit, because, my "nipples" through the wall are only 14". I'm using the 75 C column, because, the lugs on the breaker are rated at that temperature. The cable's insulation is RHH/RWH and rated at 2000V. I'm leaning towards this, because it's made with tinned stranded wire, which will provide the flexibility that I'm going to need. I'll use uninsulated wire ferrules at my termination points. Does anybody see any issues that I might run into?
 
There may be issues that i don't recognize but the first two things that come to mind when anyone mentions DLO cable is its' acceptance as a NEC wiring method and your dual rating as RHW removes that concern. My second would be that you must be sure to note a new provision in 100.14: "Terminals used for flexible, fine-stranded conductors and cables shall be identified for such use."
 
Those ampacities appear to be the "free air" ampacities. You can't use those in most cases. I am not sure how you get the correct NEC ampacities for the odd sized DLO cables. When I use DLO/RHW cables I use the NEC ampacity from the next smaller size as shown in Table 310.15(B)(16).
 
don_resqcapt19 said:
Those ampacities appear to be the "free air" ampacities. You can't use those in most cases. I am not sure how you get the correct NEC ampacities for the odd sized DLO cables. When I use DLO/RHW cables I use the NEC ampacity from the next smaller size as shown in Table 310.15(B)(16).
Click to expand...

When we use DLO conductors we push the limits, but we are utilizing them for short duration load test, with open conductors.
 
A few things that I realized on my way home: 12 not 16 conductors, and yes that chart was for "free air". I don't have the chart with me now but I do believe that the 535.3mcm was 394A (up to 3 conductors in a conduit). So I'm 18A short of 1200A. I will have to go with 646.4mcm (3 sets), which will put me well over 1200A. I guess my question now is that, can I use wire ferrules with fine stranded wire and still meet the NEC requirement. Thanks for the input.
 
As noted in post 2 "terminals identified for the use"
If I recall correctly the lug or terminal will be identified by the number of strands.
If this is an inspected job I would defiantly suggest you run the plan by the AHJ before proceeding.
You are sailing in waters seldom navigated
 
SC (stage cable) is another option. It's pretty user-friendly (flexible), and it's ampacities are listed in Table 400.5(A)(2).
 
You need to take a good read on 110.14(C)(1)

It is my understanding that you cannot use those DLO cables at the ampacities you desire.

You will have to use Table 310.15(B)(16) to select your ampacities unless you can provide documentation on the termination points that say otherwise. While most people I've talked to agree that the terminations can accept the higher ampacities, no one has ever been able to provide the "listing" for that use.
 
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