MICC

Mineral insulated cable has been described in Chapter 2. It was there explained that its
chief advantage is that it needs no protection and can be put into places where it would be
difficult to install other cabling systems. The fact that it needs no protection and is so
robust makes it very easy to install.

It can be clipped to walls and ceilings in a similar way to PVC sheathed cable. Sharp
bends should, however, be avoided, and a safe rule is to keep the radius of each bend to
more than six times the cable outside diameter. Clips or saddles should be fixed at a
spacing equal to 75 times the cable outside diameter. If the cable is to be buried within
the structure, it should be fixed down firmly before concrete or cement is poured over it.
Accessories are contained in standard boxes and the MICC cable is brought into the
boxes. Where it enters a conduit box or the terminal box of a machine, it ends in a seal
and a gland. The seal forms the end of the cable and prevents moisture getting into the
mineral insulation; it seals the cable. The gland joins the cable to the cable entry on the
box, switch or other equipment and provides earth continuity between the cable sheath
and the box or equipment case. An assembled seal is shown in Figure 3.18 and the
procedure for making it is as follows.
The end of the cable is cut to length and a notch is made round the sheath with a
ringing tool. The sheath is then stripped off the cable, from the cable end to the notch,
and the mineral insulation is broken away to expose the conductors. Alternatively a
proprietary stripping/ringing tool may be used. At this stage, the gland should be slipped
over the cable and pushed up out of the way while the seal is being finished. The gland
will then be in place to be brought forward over the seal after the latter is completed.
The insulating sleeves are now assembled. The sleeves are cut to the length required,
which may need extension sleeving for very long tails. When the sleeve is pushed
through the hole in the cap, the wedge prevents it from being pulled right through and
keeps it in place after the seal is assembled.