grounding in cable tray

[pbakhtiar]

Hi everyone,
I'm designing a1600a parallel conductor connection between a MCC and an ATS. I have to run these conductors in a single cable tray. I'm using General Cable's 646.4 DLO running (4) per phase and off course triplexed. I want to know if I can run only (1) 4/0 AWG for grounding with one of the triplexes or should I run a 4/0 grounding with each of the triplexes?

 

[lakee911]

Hi everyone,
I'm designing a1600a parallel conductor connection between a MCC and an ATS. I have to run these conductors in a single cable tray. I'm using General Cable's 646.4 DLO running (4) per phase and off course triplexed. I want to know if I can run only (1) 4/0 AWG for grounding with one of the triplexes or should I run a 4/0 grounding with each of the triplexes?

Why are you running DLO wire?

 

[qcroanoke]

Why are you running DLO wire?

It is really flexible and has the ratings for the intended use.

Diesel Locomotive Cable 2000V ? UL ? RHH/RHW

600V ? CSA R90 ? CT Rated




•Temperature rating: -40? C to +90? C
•Insulation: EPDM
•Jacket: CPE
•Resistant to oil, alkalies, acid, heat, flame
•Tinned coated copper stranding
•Sunlight resistant for CT use
•Color: black
•Approvals: UL, MSHA, CSA

The grounding question I will defer to others more knowledgeable.

 

[john2mcc]

according to 250.122 you can install a single ground conductor in raceway as long as it is sized for the largest ckt in that raceway

 

[qcroanoke]

according to 250.122 you can install a single ground conductor in raceway as long as it is sized for the largest ckt in that raceway

Cable tray is not a raceway, it is a means of support. Also a lot of cable tray systems are listed as an equipment ground. So he MAY not even have to run an equipment ground with the ungrounded conductors. I don't think he needs to, but I've been wrong many times in the past.

 

[steve66]

I've asked and debated this same question before, but I still don't have a definate answer.

If this will be inspected, I would suggest asking the inspector what they will require.

If you run a ground in any of the triplexed cables, then I believe you need a 4/0 ground in each cable per 250.122F and table 250.122.

If you have a metal cable tray, then like qcroanoke, I'm not sure you need a ground wire. But you may want to consider how the tray and cables terminate, and what they terminate to.

This doesn't pertain to the original question, but can you get 1600 amps of capacity in 4 cables??

 

[rbalex]

Basically, the problem is that CMP 3 and 6 have unnecessarily tinkered with CMP 5?s jurisdiction over equipment grounding conductors (EGC) and introduced requirements that are more restrictive than Article 250. (I know both current and past members of CMP 3 & 6 that agree with me but trying to get it corrected has been a lost cause ? I gave up several cycles ago.)

In any case, a separate EGC is unnecessary ? if only Art 250 is applied. Begin with Section 250.134 and cross reference 250.134(A) with 250.118(7). Also note the clause in 250.134(B), ??otherwise run with?? Installed properly, a cable tray installed per 396.7 meets both criteria.