Why is jacket and shield removed...?

[Julio Trujillo]

Although I've seen this for many years at the utility company, no one has explained to me clearly why this is done. Please excuse if I use the wrong terms, I had no need for them until now.

High voltage utility cable, usually for 4KV or 13KV here in Puerto Rico, is used whole for overhead outdoor lines and inside conduits. But when used in transclosures, vaults, or any indoor protected area, linemen remove the jacket and shield and leave it with just the dielectric insulation. They do this for any piece of line not going into a conduit, and for jumpers/bridge connecitons (are those the correct terms?). What I've been told is that indoors those "layers" are unnecesary, without them the cable is lighter and easier to handle.

Personally, I think it's a loss of time and money. Also, deterioration seems to be faster.

I tried to find info online, but I can't find anything...nothing. So I came to the forums; the only thing I found was an anecdote from a manufacturer, stating that the jacket is solely for mechanical protection.

So, please, anyone?

 

[Julio Trujillo]

I was told, also to avoid the use of stress-cones.

 

[keith gigabyte]

no jacket

no jacket

Don't hold me to this but when I was doing (10 years ago) H.V. cable terminations 13.8kv I was told/explained the shield was for static discharge on long runs. Seems to make sense to me since the phase conductor is insulated followed by a semiconductor then shield and finally outer jacket. I can't remember if outer jacket had an insulation value or not.

 

[Julio Trujillo]

I have read that, because of the electric field, a charge is created on the outside of the insulator, it's not static. The shield provides a path to ground for the charge and effectively reduces the range of the electric field, which helps to avoid damage to the cable and arc discharges.

But then, those are reasons that should make stripping those layers undesirable.