IG-247-EN version 02; 08/12/2020
18
Installation
General instructions
cms
.21
5.4. Preparing the location
Before installing the
cms
.21 it is necessary to fi rst excavate
and have an earthing network, which will later connect to
the
cms
.21 earth.
Basic health and safety regulations should be followed
when digging. The following is recommended in this regard:
1.
Before starting to dig, carry out a preliminary study
of the ground in order to know its stability and the
possible existence of ducts.
2.
Avoid the build-up of excavated material and equipment
along the edge of the pit. Precautions should be taken
to prevent the walls collapsing and to ensure excavated
material and equipment does not fall to the bottom of
the pit.
3.
In general, keep an area of 3 m around the perimeter of
the free of loads and circulating vehicles.
The recommended excavation levels are:
trench levels
Length
[mm]
Depth
[mm]
Depth
[mm]
3668
2733
676
Table 5.2.
trench levels
These trench levels will adapt in each case to the
solution implemented for the earthing network.
Do not exceed the horizontal line in the exterior walls,
which marks zero installation level (see Figure 1.9).
Maximum trench depth: 576 mm.
(*) 50 mm in the case of unstable ground, and add the thickness of the
reinforced concrete slab in order to determine the digging depth
Figure 5.6.
Dimensions (in mm) of the pit
5.4.1. Levelling process
Levelling the ground is important for correct installation of
the
cms
.21 . The following equipment is recommended for
correct levelling:
Quantity
Recommended equipment
1
Spirit level
1
Square-end spade
8
Levelling tools
Table 5.3.
Recommended equipment for levelling
As a general rule,
Ormazabal
recommends having a
100 mm-thick compacted and levelled layer of sand at
the bottom of the trench in order to prevent diff erential
settlements. In the case of unstable ground only, using
a reinforced concrete slab is recommended, covering it
with a bed of sand 50 mm thick. The installation operation
is reduced to positioning the
cms
.21 in the trench made
for this purpose, and connecting the cables for medium
voltage and exterior earthing.
