Armouring represents a mechanical protection of the cable but can also be used for shielding. Potential equalization via the armouring cannot be recommended but should be measured or dimensioned in each particular case and belongs to the responsibility of the customer.
If the armouring is used as electrical shielding, the shielding should be grounded at one side only to protect against ground returns and equalizing currents, i.e. the armouring should end insulated in a plastic gland.
PA system manufacturer does not recommend the armouring's grounding at both sides. This would be allowed only within a PA area and could cause interferences of the communication quality
If special metal armoured glands are used, the following parameters always have to be indicated when selecting the glands:
· Outside cable diameter
· Outside diameter of the armouring
· Desired type of thread
· Ambient conditions (range of temperatures, IP protection degree)
· Industrial or Ex version (Ex-d, Ex-e)
· Sealing: - only outside sheath - only inside sheath - outside and inside sheath - outside sheath and lead cover
· Armouring type and wire strength