DLO (Diesel Locomotive Cable) and the NEC

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kpezzoni

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I am hoping some of the veterans out there can give me some insight and there experiences on the use of DLO (UL listed of course) for use as building wire. The application requires large conductor sizes and some pretty tight bending radius that would make it next to impossible to install with traditional methods. The AHJ approved the design with DLO, but now they want it torn out. How have you guys resolved the following issues in the past with the AHJ:

1. The DLO in question is UL listed as a RHW/RHH-2 cable and CT rated. Has anyone ever encountered a restricted UL label such DLO label for RHW/RHH-2 is only applicable under certain conditions? My current argument is if its is UL labeled as RHW/RHH-2 it complies with Article 310, it is allowed for use as noted within NEC Chapter 3 (NEC 310.13).

2. Once you get above 4/o the conductor sizes get ?oddball?. My design as approved interpolated between conductor sizes per the 310 Tables (i.e., 535.3MCM on Table 310.17, 75degC is 620A). Has anyone else used this methodology or did they just round down to the next published conductor size? Or has anyone tried a NEC 310.15(C) supervised calculation?

3. This one surprise me since the original design complied with NEC 392.11(B)(3), but when the Owner threw another feeder into the mix during construction that Code section was kaput (lucky me). Now if I specified 535.3MCM, how do you resolve 392.11(B)(1) and (2)? Average the 2 conditions or throw more copper into the project and just comply with 392.11(B)(2)?

4. Does anyone know of any UL486 or NEC nuances that says you cannot use a Class DLO or equivalent highly flexible, stranded cable termination for general wiring. I am just asking to have an answer for the AHJ in case they ask, because I can already see an argument that the terminations for DLO are only for a NEC 400 cord connection and not a NEC Chapter 3 installation, or that the UL listing is only good for factory assembled equipment.

I have specified DLO in the past without any problems (knock on wood) but this current project has thrown all kinds of problems that I thought I had reasonably resolved in the past. Things have been fairly diplomatic so far and the last thing I want to have happen is have the AHJ use the infamous NEC 90.4 triumph card and me becoming an engineer who knows where you can get a great deal on some DLO cable :smile:

Any insight and/or experiences will be greatily appreciated by this EE.
 
kpezzoni said:
The DLO in question is UL listed as a RHW/RHH-2 cable and CT rated.
Click to expand...

If the cable has a listing RHW/RHH-2, you should be able to use it as that type - any other listings with non-NEC types are irrelevent. Most of the THHN/THWN wire I use also has an MTW rating on it - this doesn't mean it's somehow less suitable. It sounds though like you don't have enough bending space for a RHW/RHH installation?

Does anyone know of any UL486 or NEC nuances that says you cannot use a Class DLO or equivalent highly flexible, stranded cable termination for general wiring. I am just asking to have an answer for the AHJ in case they ask, because I can already see an argument that the terminations for DLO are only for a NEC 400 cord connection and not a NEC Chapter 3 installation, or that the UL listing is only good for factory assembled equipment.
Click to expand...

Take a look at 310.8(A) in the 2008 NEC. Also take a look at Table 400.4 in the 2008 code - it lists all of the approved flexible types, and DLO is not on the list.

P.S. - Shouldn't the '-2' above be after the wire type with the 'W' in it? Not claiming you made an error, just curious.
 
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kpezzoni said:
I am hoping some of the veterans out there can give me some insight and there experiences on the use of DLO (UL listed of course) for use as building wire. The application requires large conductor sizes and some pretty tight bending radius that would make it next to impossible to install with traditional methods. The AHJ approved the design with DLO, but now they want it torn out. How have you guys resolved the following issues in the past with the AHJ:

1. The DLO in question is UL listed as a RHW/RHH-2 cable and CT rated. Has anyone ever encountered a restricted UL label such DLO label for RHW/RHH-2 is only applicable under certain conditions? My current argument is if its is UL labeled as RHW/RHH-2 it complies with Article 310, it is allowed for use as noted within NEC Chapter 3 (NEC 310.13).
Click to expand...
Use it all the time for just such applications. As long as it is listed RHW/RHH-2, and you have it terminated with the proper compression connectors listed for such cable your AHJ has no grounds to reject it.
 
I use DLO all the time, although I actually refer to it as RHW/RHH-2 with the bending properties of DLO, so the AHJ doesn't get nervous.
I use table 300.16 and always use the standard size row the is appropriate for the DLO rounded down to the nearest standard ampacity.
 
There are some legitimate issues with using diesel cable. You normally cannot use regular equipment lugs because they are not listed for the many fine strands diesel cable is made from. You need to terminate the cables with special compression lugs listed for this purpose.

Incidentally, Marathon has recently come out with a line of distribution blocks UL listed for use with this type of cable.

There have been a number of fires that resulted from using this kind of cable and terminating them on the normal lugs equipment is supplied with.
 
kpezzoni said:
I am hoping some of the veterans out there can give me some insight and there experiences on the use of DLO (UL listed of course) for use as building wire. The application requires large conductor sizes and some pretty tight bending radius that would make it next to impossible to install with traditional methods. The AHJ approved the design with DLO, but now they want it torn out. How have you guys resolved the following issues in the past with the AHJ:

1. The DLO in question is UL listed as a RHW/RHH-2 cable and CT rated. Has anyone ever encountered a restricted UL label such DLO label for RHW/RHH-2 is only applicable under certain conditions? My current argument is if its is UL labeled as RHW/RHH-2 it complies with Article 310, it is allowed for use as noted within NEC Chapter 3 (NEC 310.13).

2. Once you get above 4/o the conductor sizes get ?oddball?. My design as approved interpolated between conductor sizes per the 310 Tables (i.e., 535.3MCM on Table 310.17, 75degC is 620A). Has anyone else used this methodology or did they just round down to the next published conductor size? Or has anyone tried a NEC 310.15(C) supervised calculation?

3. This one surprise me since the original design complied with NEC 392.11(B)(3), but when the Owner threw another feeder into the mix during construction that Code section was kaput (lucky me). Now if I specified 535.3MCM, how do you resolve 392.11(B)(1) and (2)? Average the 2 conditions or throw more copper into the project and just comply with 392.11(B)(2)?

4. Does anyone know of any UL486 or NEC nuances that says you cannot use a Class DLO or equivalent highly flexible, stranded cable termination for general wiring. I am just asking to have an answer for the AHJ in case they ask, because I can already see an argument that the terminations for DLO are only for a NEC 400 cord connection and not a NEC Chapter 3 installation, or that the UL listing is only good for factory assembled equipment.

I have specified DLO in the past without any problems (knock on wood) but this current project has thrown all kinds of problems that I thought I had reasonably resolved in the past. Things have been fairly diplomatic so far and the last thing I want to have happen is have the AHJ use the infamous NEC 90.4 triumph card and me becoming an engineer who knows where you can get a great deal on some DLO cable :smile:

Any insight and/or experiences will be greatily appreciated by this EE.
Click to expand...

I use DLO-TC all the time for large transformers secondary conductors.

You may want to ask the specific reasons why the instalaltion does not meet the NEC. Ask ofr specific refereces in the Code.

If it has to do with the ampacity of the oddball conductor sizes then you can ask a PE to approve the design and you will be in compliance with that provision of the Code. You may also just use the manufacturer's listing of the amerage rating if that is listed with a Code reference as to the installation method (three conductors in free air, whatever), because it was calculated by an engineer therefore meets the COde.
 
jdsmith said:
If the cable has a listing RHW/RHH-2, you should be able to use it as that type - any other listings with non-NEC types are irrelevent. Most of the THHN/THWN wire I use also has an MTW rating on it - this doesn't mean it's somehow less suitable. It sounds though like you don't have enough bending space for a RHW/RHH installation?



Take a look at 310.8(A) in the 2008 NEC. Also take a look at Table 400.4 in the 2008 code - it lists all of the approved flexible types, and DLO is not on the list.

P.S. - Shouldn't the '-2' above be after the wire type with the 'W' in it? Not claiming you made an error, just curious.
Click to expand...

You're right, in haste to post my message I should have written RHH/RHW-2, my bad. I am not too concerned (or should I say I wasn't) with the DLO designation when the cable is UL labelled as RHW-2, or valid listing under Article 400 since I would not comply with 400.8(1) and (6). At this point I am more worried there is something buried within the UL labelling of high press connector suitable for DLO that would void its use in the Code under a Chapter 3 installation.
 
weressl said:
I use DLO-TC all the time for large transformers secondary conductors.

You may want to ask the specific reasons why the instalaltion does not meet the NEC. Ask ofr specific refereces in the Code.

If it has to do with the ampacity of the oddball conductor sizes then you can ask a PE to approve the design and you will be in compliance with that provision of the Code. You may also just use the manufacturer's listing of the amerage rating if that is listed with a Code reference as to the installation method (three conductors in free air, whatever), because it was calculated by an engineer therefore meets the COde.
Click to expand...

The biggest hurdle right now is the claim by the AHJ is they are not accepting the mfgr's the UL label and the oddball size is not listed within the 310 Tables. :confused: One would think that if the design is stamped and sealed and the plan checker approved it, then the inspector should not have a problem.

Another hurdle I need to address is the gap in 392.11 and attempting to argue the point that I shouldn't need to round the allowable ampacity down to 65% which well likely require another set of conductors, but then again this might be a non-issue if a 500MCM table value is used.

Guys, thanks for the input so far! :smile:
 
kpezzoni said:
...At this point I am more worried there is something buried within the UL labelling of high press connector suitable for DLO that would void its use in the Code under a Chapter 3 installation.
Click to expand...

Repeating to self: it's RHH/RHW not DLO, it's RHH/RHW not DLO, it's RHH/RHW not DLO:smile:

Do you have the brand and part number of the hypress connectors available? The UL white book is available online, and that combined with the manufacturer's data sheet should make your case for you - or the inspector, depending on how things are listed. Shouldn't be too hard to dig up though.
 
I just saw some 10AWG cable that was marked "diesel locomotive cable" RHW/RHHW. That was new for me. It was used for the PV module wiring for a solar array. It is listed as acceptable in art. 690 for that use.
 
kpezzoni said:
The AHJ approved the design with DLO, but now they want it torn out.
Click to expand...
This is the issue I'd start with. Let you install it and then change their minds? Grrr! :mad:
 
I dont see why you cant calculate the ampacity using the CSA? RHW is RHW I dont see why this is a problem?
I would evaluate the bending radius and the terminations. The cable might not be the problem.
I believe DLO insulation is far better than THHN and would consider it a substantial upgrade to standard building wire.
 
Anybody heard if class B stranding?

Anybody heard if class B stranding?

One has to turn over a lot of rocks to find the answer for this one. I strongly believe that the manufacturers of breakers and similar devices should point out that class B stranded wire is only allowed unless otherswise listed. I also believe that the NEC shoulld clarify this also.

Panel builders just loved that fine stranded stuff because of its flexibly. One panel builder had catostphic failure that basically destyroyed the area between the A and B phases of a 250A 3-pole breaker. I personally keep that breaker as an example of such a failure.

As a former breaker application engineer the question of the use of locomotive and welder's cable came up a lot so much in fact that I began to research just what was involved in cable application. I knew that there was more to applying the correct cable size and insulation class.

What I found out was what UL 486 for terminals was based upon. I have to admit that it is very difficult to determine what stranding is allowed with UL 489A-B. What I discovered was that only "class B" stranding was allowed. I have not found this anywhere in the instruction for terminal application.

From what I understand UL486 involes torqueing the the rated wire to a specific torque in a given terminal, running a given value of current through the terminag to assure that it is within the temperature rise, doing a pull test of a specific amount of pull etc.

Stranding greater than class B is considered to be fine stranded an can only be used with terminals listed order marked for use with fine stranded wire.
After a little "googling" research I found a fairly good explanation. It even shows a terminal failure due to the use of fine stranded cable.

The following document explains the fine stranding incoptabilities of set scew terminals and lugs.

http://www.nmsu.edu/~tdi/pdf-resources/pdf version divided PV:NEC/APPENDIX K.pdf

Fine stranded conductor can not be adequately secured with the common terminals. After the 250a breaker failure I illustrated to the OEM that even though they had followed the recommended torque requirements that the conductor still wasn't secure in the terminal. I had them look at an exposed end of a terminal that was torqued to spec and showed then that the center group of strands wiggled and moved around as if they weren't tightened at all.
Such a connection generated heating, the heating caused expansion and the heating and cooling cycle due to the dynamics of the load being supplied the termination begins to loosen which creates more heat. The heating and cooling cycles continues until the connection is so poor that it begins to arc.

The arcing ionizes the air and involves the grounded mounting surface. The ionized air between the phase and ground involves the adjacent phase expands and involves the adjacent phase which escalates into a phase a phase to phase arcing fault. It gets pretty ugly to say the least.
While visiting another well-known OEM I discovered that they to were using fine stranded wire in making their connection also. Again I demonstrated the error of their ways.

The bottom-line? Use a crimp on ring tongue terminal or other termination UL listed for terminating fine stranded cable, remove the existing terminal on the breaker, contractor, etc, an bolt the ring tongue terminal in place.
 
kpezzoni said:
The biggest hurdle right now is the claim by the AHJ is they are not accepting the mfgr's the UL label and the oddball size is not listed within the 310 Tables. :confused: One would think that if the design is stamped and sealed and the plan checker approved it, then the inspector should not have a problem.

Another hurdle I need to address is the gap in 392.11 and attempting to argue the point that I shouldn't need to round the allowable ampacity down to 65% which well likely require another set of conductors, but then again this might be a non-issue if a 500MCM table value is used.

Guys, thanks for the input so far! :smile:
Click to expand...

The tables do not reflect the only wire sizes allowed. They are a maximum ampacity for a specific wire size. You can always use a conductor that is larger than the table shows for a required ampacity.
 
Remember that using other than class B stranding in a UL486 terminal will be in violation of NEC Art 110-2 and 110.3(b) Installation and use. Locomotive cable does not have class B stranding which is 7, 19, and 37 strand

But remember that the class B stranding requirement is a very well kept secret as companies like Illsco manufacture the lugs to comply with UL486 and the breaker manufacture purchases those lugs from them. However from that point on that type of rated wire that the lug has be listed with gets lost.


Another link which illustrates treminal failure.

http://store.altenergystore.com/Cab.../p1204/pdfs/solarpals/IAEI_Cables_Article.pdf
 
Based on the information provided in this thread most terminations are only listed for Class B stranding. That would prohibit the use of the products that are THHN/THWN/MTW. This wire would have 19 strands in the smaller sizes, where Class B stranding would have 7 strands. Is that a real world problem or just a listing problem?
 
templdl said:
One has to turn over a lot of rocks to find the answer for this one. I strongly believe that the manufacturers of breakers and similar devices should point out that class B stranded wire is only allowed unless otherswise listed. I also believe that the NEC shoulld clarify this also.

Panel builders just loved that fine stranded stuff because of its flexibly. One panel builder had catostphic failure that basically destyroyed the area between the A and B phases of a 250A 3-pole breaker. I personally keep that breaker as an example of such a failure.

As a former breaker application engineer the question of the use of locomotive and welder's cable came up a lot so much in fact that I began to research just what was involved in cable application. I knew that there was more to applying the correct cable size and insulation class.

What I found out was what UL 486 for terminals was based upon. I have to admit that it is very difficult to determine what stranding is allowed with UL 489A-B. What I discovered was that only "class B" stranding was allowed. I have not found this anywhere in the instruction for terminal application.

From what I understand UL486 involes torqueing the the rated wire to a specific torque in a given terminal, running a given value of current through the terminag to assure that it is within the temperature rise, doing a pull test of a specific amount of pull etc.

Stranding greater than class B is considered to be fine stranded an can only be used with terminals listed order marked for use with fine stranded wire.
After a little "googling" research I found a fairly good explanation. It even shows a terminal failure due to the use of fine stranded cable.

The following document explains the fine stranding incoptabilities of set scew terminals and lugs.

http://www.nmsu.edu/~tdi/pdf-resources/pdf%20version%20divided%20PV:NEC/APPENDIX%20K.pdf

Fine stranded conductor can not be adequately secured with the common terminals. After the 250a breaker failure I illustrated to the OEM that even though they had followed the recommended torque requirements that the conductor still wasn't secure in the terminal. I had them look at an exposed end of a terminal that was torqued to spec and showed then that the center group of strands wiggled and moved around as if they weren't tightened at all.
Such a connection generated heating, the heating caused expansion and the heating and cooling cycle due to the dynamics of the load being supplied the termination begins to loosen which creates more heat. The heating and cooling cycles continues until the connection is so poor that it begins to arc.

The arcing ionizes the air and involves the grounded mounting surface. The ionized air between the phase and ground involves the adjacent phase expands and involves the adjacent phase which escalates into a phase a phase to phase arcing fault. It gets pretty ugly to say the least.
While visiting another well-known OEM I discovered that they to were using fine stranded wire in making their connection also. Again I demonstrated the error of their ways.

The bottom-line? Use a crimp on ring tongue terminal or other termination UL listed for terminating fine stranded cable, remove the existing terminal on the breaker, contractor, etc, an bolt the ring tongue terminal in place.
Click to expand...

One can use ferrules to 'bunch' the fine strands of a DLO cable after which it becomes perfectly suitable to terminate it on any terminals that are designed for solid conductors. The spec usually calls for "solid or Class B, C stranded conductors".
 
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