Where cable enclosure greater than 32mm required because
of the number size the conductors, generally more economical
and convenient use trunking.
PVC insulated cables are usually drawn into erected conduit installa-
tion laid into erected trunking installation. 14.Electrical installations and wiring systems
313
Where any trunking passes through walls, partitions, ceilings floors,
short lengths lid should fitted that the remainder the lid may
be removed later without difficulty. Figure 14.
. Any damage the structure the
buildings must made good with mortar, plaster concrete order to
prevent the spread fire. Fire barriers must fitted inside the trunking
every 5m, every floor level room dividing wall, this shorter
distance, shown Fig.
TRUNKING CAPACITIES
The ratio the space occupied all the cables conduit trunking to
the whole space enclosed the conduit trunking known the space
factor.29(a). Where sizes and types cable and trunking are not covered the
FIGURE 14.29
Installation trunking: (a) fire barriers trunking and (b) cable supports vertical trunking.29(b) shows cables woven through
insulated pin supports, which one method supporting vertical cables.
(a)
Room-
dividing
wall
Fire barriers
Trunking
Building structure made
good after installation
Cables
(b)
Definition
The ratio the space occupied by
all the cables conduit trunking
to the whole space enclosed the
conduit trunking known the
space factor. Table the Site
Guide only gives factors for conduits 32mm diameter, which
would indicate that conduits larger than this are not frequent com-
mon use.
Where trunking installed vertically, the installed conductors must be
supported that the maximum unsupported length non-sheathed
cable does not exceed 5m
