Basic Electrical Installation Work
318
The cable may laid directly the ground, ducts, cable tray or
clipped directly structure. simple
continuity polarity test, described later this chapter, can identify
the conductors which are then sleeved identified with coloured markers. not affected water, oil the cutting
fluids used engineering and can withstand very high temperature or
even fire. 14.5), see Table 14.5. These characteristics make the cable ideal
for Band emergency circuits, boiler-houses, furnaces, petrol stations and
chemical plant installations. When bending cables the radius the bend should not
cause the cable become damaged and clips should provide adequate
support (Regulation 522.
Connection cables can made directly motors, but absorb the
vibrations 360° loop should made the cable just before the termina-
tion.
.
The conductors are not identified during the manufacturing process and
so necessary identify them after the ends have been sealed.
The cable must prepared for termination removing the outer copper
sheath reveal the copper conductors. excessive vibration expected the cable should termi-
nated conduit through box and the final connection made flexible
conduit. The cable can be
work hardened over-handled over-manipulated. reduce the risk dam-
age the outer sheath during installation, cables should straightened
and formed hammering with hide hammer block wood and a
steel hammer. Such assembly suitable for working tempera-
tures 105°C.
Cable ends must terminated with special seal prevent the entry
of moisture. This can achieved using a
rotary stripper tool or, only few cables are terminated, the outer
sheath can removed with side cutters, peeling off the cable simi-
lar way peeling the skin from piece fruit with knife. Figure 6.26 for conduit. This prevent moisture from penetrating the
seal capillary action. The cable diameter small relation its current carrying
capacity and should last indefinitely correctly installed because is
made from inorganic materials. The outer sheath the
cable must not penetrated, otherwise moisture will enter the magne-
sium oxide insulation and lower its resistance. Other compounds powdered glass can increase the
working temperature 250°C.3 shows brass screw-on seal and gland assembly,
which allows termination the cables standard switchgear and con-
duit fittings. The sealing pot filled with sealing compound, which is
pressed from one side only prevent air pockets forming, and the pot
closed crimping home the sealing disc with crimping tool such as
that shown Fig 7. All excess magnesium oxide powder must wiped from the conduc-
tors with clean cloth. When enough
conductor has been revealed, the outer sheath must cut off square to
facilitate the fitting the sealing pot, and this can done with ringing
tool. This makes the cop-
per outer sheath stiff and may result fracture.4.8.
The cable supplied coils and should run off during installation and
not spiralled off, described Fig
