Firstly, for the mega projects, infrastructure networks are considered the artery of the project, which will feed all the different buildings & landscape works with different electrical, mechanical, and low current sources.
Let us have a look at these different MEP networks, which can be found in Infrastructure. We will divide these networks into three categories: electrical networks, mechanical networks, and low current networks.
1- Electrical networks:
These networks can be divided into two subcategories.
1.1- Medium Voltage network:
This network mainly will be found in big projects.
Again we can find this medium voltage in two main scenarios.
The first scenario is the MV network can feed either the medium voltage switchgear or the ring main unit which will be available in the project.
The second scenario is this MV network will feed a medium voltage station which will step down the voltage from example from 22KV to 11KV like in Egypt, or it can be in some other cases from higher KV ranges to be decreased up to 13.8KV, like in Saudi Arabia.
For the first scenario “MV network in Infrastructure”, your buildings in the project will require a low voltage source to energize all the different MEP equipment with the power, examples of these types of equipment (Chillers, Air Handling Units, SMDB, DB, Pumps…etc).
But may you ask yourself: why do we need medium-voltage cables to feed the mega-project, when we can use Low Voltage directly?
The main reason is to overcome the voltage drop that occurs during power transfer: for the same load power, increasing the voltage decreases the current, and hence the voltage drop decreases.
1.2- Low Voltage networks:
This network can be found in different scenarios; for example, it is used to feed the landscape lighting.
Or, this network we use to feed the street lighting poles.
Or, we use it to feed the pump rooms in the infrastructure, like the pumps that will be used to operate the swimming pools.
Or, the low-voltage cables will be used directly to power the building itself, such as villas in a compound, or buildings that don’t include a step-down transformer from Medium Voltage to Low Voltage.
And so on.
2- Mechanical networks:
Now we will discuss the mechanical services and systems available in Infra Works.
2.1- Drainage/Sewage network:
You can say this is the most important network of the MEP systems in Infra works.
The main reason is that this network’s installation depends on the slope of its pipes/lines.
The line’s least slope will correspond to the farthest point along the main sewage line.
Let us assume the slope of the main drainage line will be 0.5 CM for each one-meter length of the pipe, so if the size of your project is huge, for example, the length of the main drainage line is around 2 KM = 2000 M for the main drainage pipe, that means the slope of this pipe from its start to end will be 1000 CM = 10 M.
2.2- Storm Water network:
The same will also apply to the stormwater network, as it depends on the slope.
So, from the previous two water systems, we can conclude that these networks, routes, and slopes must be respected, as most other networks are pressurized like Water Supply networks or Gas networks, or non-water networks like electrical and low-current networks.
2.3- Water Supply Network:
Simply, this network will transfer potable water from the water supply pumps to the different buildings and water fountains in the landscape, and can also feed water to drinking fountains.
2.4- Irrigation network:
This network will be used to irrigate all planters and landscape areas.
This network is pressurized as it transfers the water from the irrigation pumps to the different landscape areas.
2.5- Firefighting network:
This network will be responsible for feeding all the fire hydrants that exist in the infrastructure, the different external fire hose cabinets, plus, based on the design of your project, it can feed the firefighting network’s zones in a project
2.6- Chilled/Hot Water networks:
These networks will be responsible for transferring cold water from the main chilled water pumps & hot water pumps, respectively, to the various mechanical units of the HVAC system located in different buildings of the project.
2.7- Steam network:
This network is mostly found in the medical project, where a central Boiler building generates steam and transfers it through this network to all locations that require steam but don’t have their own local steam unit. For example, the central laundry building, the hospital, and so on.
Now, I will talk about the third category of the MEP systems
3- Local Current networks:
Mainly due to the long length of these networks, their cables will be almost fiber-optic.
The type of fiber optic cable (FOC) will be almost single-mode FOC. It can travel for longer distances than the multi-mode FOC.
These low-current systems will be used for the data networks, IPTV systems, fire alarm systems, etc.
You shall note that all the above MEP systems in the three categories will require either manhole, handholes, or both, or valve chambers (for pressurized water systems & gas networks).
Each one will have a specific depth based on the standards, manufacturer recommendations, and your approved shop drawings.
So, we can conclude that for infrastructure networks, you must have very good coordination of MEP drawings to avoid clashes during the installation of your systems and to avoid wasted time and manpower.
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