We
are using FONDINSONSO AP-5125 Plug and EPC1-1P125B Socket. It is a 5 pin socket and plug rated at 125A. The cable
that we use is CU/XLPE/PVC/SWA/PVC-FR 0.6k/1kV. It is a 4 core cable with a shield. The length of the cable
is 100m. 3 cores are used as live and 1 as neutral. The cable shield is grounded to earth at both ends. Is this type of installation correct? Or do we need to use a 5 core cable and use the fifth core as grounding instead of the cable shield? This installation is used to supply power to a remote distribution panel from a generator set.
I have asked this question to a local company which does power cable installation and the answer was given as below. I search around the net and found some articles saying that the shield is supposed to be grounded. Which is correct?
"Basically
there should be 4 numbers ( 3 phase), Red, Yellow , Blue, Neutral . The
earth comes from the grounding of the generator set that is connected
to the earth pit., therefore altogether, there should be 5 numbers of
cables, that is connected from the generator to a switchboard panel and
since the distance is 100 meters, then you probably use 4 numbers of
cables / 4 core connected to the switchboard, the earth cable will be
probably from the switchboard earthing pit. If that is so, please
make sure the earth resistance measurement be less then 1 ohm.
FYI
cable shield (armoured) is never used for earthing purpose. They are
used as a mechanical protection for the internal cables/ core. To
answer your question below, please check if there is any earthing done
for the generator and the switchboard first, and then you will be safe.
Continuity test on the shield is not necessary and would not pose any
issue."
Power Cable Installation (4 Core With Shield?)
Re: Power cable installation (4 core with shield?)
