Shielding MV Cables

It depends on details you have not supplied.

Companies that deal with these things have procedures to follow. It pays to read them.

Here is one reference:

"Grounding Shielded Cable

When installing shielded cable, metallic shielding must be solidly grounded. Where conductors are individually shielded, each must have its shielding grounded and the shielding of each conductor should be carried across every joint to assure positive continuity of a shielding from one end of the cable to the other. Where grounding conductors are part of the cable assembly, they must be connected with the shielding at both ends of the cable.

For safe and effective operation, the shielding should be grounded at each end of the cable and at each splice. For short lengths or where special bonding arrangements are used, grounding at one point only may be satisfactory."

Ref: http://www.okonite.com/engineering/shielding.html

Your statement is true for low voltage cabling however it does not apply to medium voltage (MV) and high voltage (HV) cabling applications.

The shields on MV and HV cables are for safety purposes and to limit corona damage from occurring to the cable and/or equipment.

All MV and HV termination kits have very specific instructions and failure to follow the correct procedure(s) will result in cable failure and/or danger to personnel up to and including loss of life.

See ANSI/IEEE 576/1989 IEEE Guide for Application of Sheath-Bonding Methods for Single-Conductor Cables and Calculation of Induced Voltages and Currents in Cable Sheaths.

For personnel safety reasons and to avoid equipment damage it is imperative you identify the cable manufacturer and the termination manufacturer then contact both for specific directions on how to terminate any and all MV as well as HV cable applications.

All MV and HV cable as well as terminations kits are specific as to the correct method and procedure required for each and every application.

Failure to follow their specific guidelines for each application will result in cable failure and/or personnel injury up to and including death as well as sever equipment damage.

It depends as Lyn says.

Based on your previous posts, do you just test LV and MV cables or are you now getting involved in system design also? Are you just qualified as (say) an electrical testing technician? The reason I ask is the nature of the question is rather.....concerning from a safety point of view.

Is this just a general interest question? If so you need to provide more information, specifically the local electrical standards you are working to (IEC, NEC, IN, etc) along with the termination method as this effects the answer. Down here, MV no longer exists, it's now called HV (for example).

Also "shield" could mean cable screen, overall cable armour sheath or semiconductive cable screen (depending on cable and standard), each with a potentially different answer (and different set of names for each).

Oh the fun with cables, many people think they are just simple insulated bits of wire with resistance that carry current.