[paulengr]

This is so over the top it’s unbelievable. The first dead giveaway is that the termination is only about 4 inches long on 4160 V. There is no stress grading, just a heat low voltage shrink tube about 4 inches long. The orange tape one. The other cable is factory unshielded 7.5 kV.

The drain wire is a nice touch. I cut another one open and it’s just touching the shield.

 

[Breakfasteatre]

thats factory wired or some hack did it?

 

[SWDweller]

I have met several people that think heat shrink on the terms is all that is needed for non shielded 4.16kv. They were all surface miners and used to things breaking all of the time.

 

[paulengr]

The one with no tape is the factory unshielded connection to the bottom of the soft start.

The one with orange tape and heat shrink on it is shielded MV-90. This was installed by a licensed contractor. Same contractor keeps doing this.

Same contractor also installed a soft starter by going in on the bottom of the fuses (on top of the contactor) in a non-load break starter (Square D model ;, the kind with the handle that turns sideways). This bypassed the disconnect interlocks since the contactor was bypassed. An operator with 2 weeks of experience unknowingly tried to open one of those disconnects onto an operating 1000 HP hammer mill. Arc flash. Burned both arms and face.

 

[SWDweller]

I have never pulled a mixture of shielded and unsheilded cables. I wonder if there is a long term issue with that? I have not worked with all that much unsheilded wire in my career.

Sorry to hear about the operator, wish him a speedy recovery. Arc Flash is no joke.

When do the law suits start? I would think the contractor is in deep do do over this. Might be a business ending event.

 

[mburtis]

I just finished doing a chapter on medium voltage terminations for my school classes. Very interesting stuff and seems like a fascinating and completely different world to normal electrical. I doubt I will ever get the chance to learn any of it unless go into mining. Definitely not the type of stuff any old electrician can do.

 

[Signal1]

The one with no tape is the factory unshielded connection to the bottom of the soft start.

The one with orange tape and heat shrink on it is shielded MV-90. This was installed by a licensed contractor. Same contractor keeps doing this.

Same contractor also installed a soft starter by going in on the bottom of the fuses (on top of the contactor) in a non-load break starter (Square D model ;, the kind with the handle that turns sideways). This bypassed the disconnect interlocks since the contactor was bypassed. An operator with 2 weeks of experience unknowingly tried to open one of those disconnects onto an operating 1000 HP hammer mill. Arc flash. Burned both arms and face.

I hate hearing this. I hope he/she recovers OK.

 

[JRaef]

It's not common for factories to use shielding on INTERNAL cable connections of MV gear and the terminations are often done that way. The entire assembly will have had to pass a BIL test and surge test, so any deficiencies in the internal conductors or terminations are found before it ships.

Unfortunately, seeing this often gives contractors in the field a perceived license to be just as lax, and that is the problem.