A single-phase circuit is to be wired in 70 °C PVC-insulated and non-sheathed single-core cables to BS 6004 having coppe
Posted: Fri Apr 29, 2022 8:32 am
A single-phase circuit is to be wired in 70 °C PVC-insulated and
non-sheathed single-core cables to BS
6004 having copper conductors. Both overload and short-circuit
protection are provided by a 32 A BS
88 Pt.2 fuse. For about the first third of its route, the cable is
installed in trunking (Installation Method
#6 and Reference Method B) with six other similar circuits at an
ambient temperature of 30 °C. For the
remaining two-thirds of its route, it is run in conduit on a wall
(Installation Method #4 and Reference
Method B) but with no other circuits and where the ambient
temperature is (40+b*2)°C (Note: use the
relevant equation, not the table, to find out Ca).
(10 marks)
(i)
What is the minimum cross-sectional area of the cable conductors
that can be used? Also
check the k S.
(ii)Is there another option in selecting the cross-section area(s)
of the cable conductors? If yes,
what is the other option? If not, what is your reason?
(iii)If there is another BS 88 Pt2 fuse at the upstream of the 32A
fuse BS88 of this circuit, what
should be the minimum rating of thatupstream fuse, in order to
ensure selectivity between
the two fuses? State clearly your reason,
non-sheathed single-core cables to BS
6004 having copper conductors. Both overload and short-circuit
protection are provided by a 32 A BS
88 Pt.2 fuse. For about the first third of its route, the cable is
installed in trunking (Installation Method
#6 and Reference Method B) with six other similar circuits at an
ambient temperature of 30 °C. For the
remaining two-thirds of its route, it is run in conduit on a wall
(Installation Method #4 and Reference
Method B) but with no other circuits and where the ambient
temperature is (40+b*2)°C (Note: use the
relevant equation, not the table, to find out Ca).
(10 marks)
(i)
What is the minimum cross-sectional area of the cable conductors
that can be used? Also
check the k S.
(ii)Is there another option in selecting the cross-section area(s)
of the cable conductors? If yes,
what is the other option? If not, what is your reason?
(iii)If there is another BS 88 Pt2 fuse at the upstream of the 32A
fuse BS88 of this circuit, what
should be the minimum rating of thatupstream fuse, in order to
ensure selectivity between
the two fuses? State clearly your reason,