Junction Box size with DLO cable

[winslowfam]

Hi...we are using Diesel Locomotive cable for a project. We need to terminate these cables in a junction box. I am looking at the NEC for direction on sizing this box based on conduit sizes entering the box (Art. 314.28) and the bending radius distance specified in Table 312.6(B). Because this cable is so flexible and has a small minimum bending radius, can I take that into account when sizing this box? I understand the minimum box size based on conduit sizes, but it seems that I can use a smaller bending radius distance with this High Flex cable.

 

[ASTERIX]

Bending Radius of DLO vs Box size.

Bending Radius of DLO vs Box size.

Hi...we are using Diesel Locomotive cable for a project. We need to terminate these cables in a junction box. I am looking at the NEC for direction on sizing this box based on conduit sizes entering the box (Art. 314.28) and the bending radius distance specified in Table 312.6(B). Because this cable is so flexible and has a small minimum bending radius, can I take that into account when sizing this box? I understand the minimum box size based on conduit sizes, but it seems that I can use a smaller bending radius distance with this High Flex cable.

I recently installed an emergency generator at my home and intercepted the 200 Amp utility feed (THHN) in plastic conduit with two 4"x 4" x 3" pull boxes (to insert the ATS). Then used # 1/0 DLO cable (3-1/c) which installed with no problem.
The town inspector never heard of "DLO" went back to his office and called me: Rejected ! (Since it was my basement, I overruled him).

The code allows a lot of qualified exceptions (which can be allowed if the inspector has an engineering degree and is also experienced). A small town inspector is (usually) an electrician who has read the NEC code twice and will not deviate from it (for lack of education on the subject).

How large a box is needed ? You must be able to install the cable(s) without damaging or over bending it. The termination studs need clearances per code. Its that simple.

We design large drive control systems for conveyors and bulk material handling machines often using custom-made pull boxes, never had an inspection problem.

 

[don_resqcapt19]

...
The town inspector never heard of "DLO" went back to his office and called me: Rejected ! (Since it was my basement, I overruled him).
...

Unless the DLO was dual rated as one of the types shown in Table 310.104(A), 310.13 prior to the 2011 code, the inspector was correct.

 

[dereckbc]

Make sure the DLO is dual rated like RHW-2. We use a lot of it in the Telecom industry of 500 and 750 MCM for battery plants in cable racks. It also requires special compression terminal and tooling to terminate it correctly. Most of the tooling is hydraulic 14 to 16 ton compression force. Look out for Shiners if tight bends are encountered near termination.

 

[don_resqcapt19]

...Look out for Shiners if tight bends are encountered near termination.

I am not familiar with that term.

 

[iwire]

Hi...we are using Diesel Locomotive cable for a project. We need to terminate these cables in a junction box. I am looking at the NEC for direction on sizing this box based on conduit sizes entering the box (Art. 314.28) and the bending radius distance specified in Table 312.6(B). Because this cable is so flexible and has a small minimum bending radius, can I take that into account when sizing this box? I understand the minimum box size based on conduit sizes, but it seems that I can use a smaller bending radius distance with this High Flex cable.

There are no exceptions to allow you to use a smaller box. You may not be able to use that cable at all.

If you can use that cable you need special terminations for it.

 

[iwire]

The code allows a lot of qualified exceptions (which can be allowed if the inspector has an engineering degree and is also experienced)

Can you give me an example of these 'qualified exceptions' other than selection of ampacity under engineering supervision?

 

[K8MHZ]

Can you give me an example of these 'qualified exceptions' other than selection of ampacity under engineering supervision?

How can an inspector play the role of engineer and supervisor on the same job?

 

[joebell]

I am not familiar with that term.

Don,

I believe the term refers to exposed conductor. I had an instructor in the Navy that used the term quite often.

 

[qcroanoke]

Can you give me an example of these 'qualified exceptions' other than selection of ampacity under engineering supervision?

I would also like to see where the homeowner is allowed to overrule the inspector.

 

[petersonra]

I would also like to see where the homeowner is allowed to overrule the inspector.

I think it is the same article that allows inspectors to enforce non-existent provisions of the code.

 

[templdl]

There are no exceptions to allow you to use a smaller box. You may not be able to use that cable at all.

If you can use that cable you need special terminations for it.

Ditto!!!!

 

[templdl]

Can you give me an example of these 'qualified exceptions' other than selection of ampacity under engineering supervision?

The only way that I can think of that DLO or the fine stranded hypalon wire could be used if it were included in a factory assembly that was UL listed. Otherwise I can't think of any way that it is allowed even though it may seem to be a logical substitute. But definitely I agree that terminations can be extremely problematic should they not be done correctly.

 

[don_resqcapt19]

The only way that I can think of that DLO or the fine stranded hypalon wire could be used if it were included in a factory assembly that was UL listed. Otherwise I can't think of any way that it is allowed even though it may seem to be a logical substitute. But definitely I agree that terminations can be extremely problematic should they not be done correctly.

Some DLO and welding cable is also marked as RHH or RHW. As long as it has those markings, it is suitable for use in NEC applications.

 

[templdl]

Some DLO and welding cable is also marked as RHH or RHW. As long as it has those markings, it is suitable for use in NEC applications.

Thanks for the heads up. So much to learn, too little time.In retrospect I wonder if either on my two OEMs had considered that as my concern had been with the way they were terminating the cable was not acceptable.

 

[don_resqcapt19]

Thanks for the heads up. So much to learn, too little time.In retrospect I wonder if either on my two OEMs had considered that as my concern had been with the way they were terminating the cable was not acceptable.

As you said the OEM does not have to comply with the NEC so I have often seen DLO or welding cable that was not dual rated installed in equipment by the OEM. I have also seen that wire landed in standard termination devices that are not suitable for use with finely stranded conductors in the same equipment.

 

[templdl]

As you said the OEM does not have to comply with the NEC so I have often seen DLO or welding cable that was not dual rated installed in equipment by the OEM. I have also seen that wire landed in standard termination devices that are not suitable for use with finely stranded conductors in the same equipment.

I had a drive OEM that terminated it on a 250a breaker using the standard terminals which the results were not so good. Because the terminals were not suited for this cable you could torque it to specs but the internal strands of the cable remained loose. The A phase terminal heated which caused the termination to loosen causing further heating which ended up to a point where it started to arc. The air ionized around it which involved the grounded panel and a arcing phase A to B fault which was not pretty. I insisted that they use a listed ring tongue terminal for that wire and then bolt it to the breaker which solved their problem.
Such an application caused me to research UL486 and and the testing required for class B and C stranding and DMO was not included.
I had kept the breaker as an example but have since discarded it.