I have a situation where we need to splice a length of shielded 8kV rated cable to non-shielded 5 kV cable for a failure repair on a 4160 volt system. Does anyone know if the 8kv cable can be treated similarly to the unshielded cable within the splice or will excessive voltage stresses be present without properly terminating the shielded cable conductors? The cable and splice kit manufacturers do not have information available to address this situation.
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Splicing Shielded MV Cable to Non-Shielded MV Cable
- Thread starter kmh1
- Start date
If this is anything but a very temporary fix, you need to properly terminate the shielded cable. Otherwise it will fail as you say, because of the high voltage stress at the end of the shield. Also, a proper termination is needed to seal out moisture. Then you can connect to the unshielded cable.
You definitely need the correct pothead and other temination devices at the end of the shielded cable - you then continue the short distance with unshielded cable.
Is there any reason for using 8 KV cable on 4,160 volts? 5 KV 3 conductor metal clad cable that has only the sheath as an overall shield works quite fine on 4,800 volts ungrounded.
Is there any reason for using 8 KV cable on 4,160 volts? 5 KV 3 conductor metal clad cable that has only the sheath as an overall shield works quite fine on 4,800 volts ungrounded.
- Thread starter
- #4
SierraJ
Electrical
- Apr 12, 2005
- 24
In addition to the issues already mentioned, you need to remember this will present some safety related issues also. Without proper grounding of the 8kV cable shield, it will act as a capacitor and maintain a dangagerous voltage even when the cable is de-energized.
- Thread starter
- #8
If the shield is not grounded, the inner jacket will have to withstand some significant portion of the line-to-ground voltage, for which it would not typically be designed.
Also, most codes require the shield to be grounded regardless of presence of armour jacket.
Also, most codes require the shield to be grounded regardless of presence of armour jacket.
- Thread starter
- #10
nickoliver
Electrical
Just for your info 3M's 5550 Series splice kits address shielded to non shielded connections right in their installation instructions.
resqcapt19
Electrical
Note that under the 2005 NEC, section 310.6 requires that all insulated conductors operated above 2000 volts, be of the shielded type.
Don
Don
- Thread starter
- #13
- Status
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