25.25
Terminating conduits.2).8.
.1 and 522.1 and 522. Any unused conduit-box entries
should blanked off and all boxes covered with box lid, fitting acces-
sory provide complete enclosure the conduit system. The radius all bends conduit must not cause
the cables suffer damage, and therefore the minimum radius bends
given Table the Site Guide applies (IEE Regulation 522.3). circuits must contain phase and
neutral conductors the same conduit prevent eddy currents flow-
ing, which would result the metal conduit becoming hot (Regulations
521. The conduit size and range fit-
tings are the same those available for metal conduit.
When drawing cables into conduit they must first run off the cable
drum. Where luminaires are suspended from PVC
conduit boxes, precautions must taken ensure that the lamp does not
raise the box temperature that the mass the luminaire supported by
each box does not exceed the maximum recommended the manufac-
turer (IEE Regulations 522. not suitable for installations subjected tempera-
tures below 25°C above 60°C.8. Conduit runs
should separate from other services, unless intentionally bonded, to
prevent arcing occurring from faulty circuit within the conduit, which
might cause the pipe another service become punctured.8. Metal conduits containing a. The spring ensures that the conduit
keeps its circular shape.
PVC CONDUIT
PVC conduit used typical electrical installations heavy gauge standard
impact tube manufactured 4607. All
conduits should terminate box fitting and meet the boxes fittings
at right angles, shown Fig. PVC conduit also expands much
more than metal conduit and long runs require expansion coupling
to allow for conduit movement and help prevent distortion during tem-
perature changes.5.2, 522. 14. Since PVC conduit insula-
tor cannot used the CPC and separate earth conductor must be
run every outlet. 14.2). PVC conduit most
often joined placing the end the conduit into the appropriate fitting
and fixing with PVC solvent adhesive. PVC conduit can bent hand
using bending spring the same diameter the inside the conduit.
The advantages PVC conduit system are that may installed much
more quickly than steel conduit and non-corrosive, but does not have
the mechanical strength steel conduit.
Spacer bar saddle
Wall
Conduit set out
to enter box at
right angles
Coupling
Male bush
Metal box
Fixing surface
Conduit
Flange
coupling
Lead
washer
Male
bush
FIGURE 14.
The spring pushed into the conduit the point the intended bend and
the conduit then bent over the knee. That is, the drum must rotated shown Fig. The metal conduit also utilized the CPC
and, therefore, all connections must screwed tightly and all burrs
removed that cables will not damaged they are drawn into the
conduit.
All conduit installations must erected first before any wiring installed
(IEE Regulation 522.Electrical installations and wiring systems
307
Metal conduits are threaded with stocks and dies and bent using spe-
cial bending machines. cold weather, little warmth applied the point
of the intended bend often helps achieve more successful bend.26 and not
allowed spiral off, which will cause the cable twist.11).8.c
