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When you are worried about the EMF radiation from house cables and power cables, don’t forget to learn about the underground cables. If there are underground cables below or near your property or office, you should read this article.
Do underground cables emit EMF radiation? Like overhead power lines, underground cables also emit EMF radiation. The electric fields they produce usually cancel out but the magnetic fields can be high. To minimize the EMF radiation from underground cables, it is better to make sure that they are deep enough in the ground.
In this article, I will share all the details about EMF radiation from underground cables. So, let us start learning!
What are the Underground Cables?
The underground cables are used for supplying power lines in areas where it is difficult, dangerous or impossible to use the overhead power lines. You will find the underground cables in:
- Urban areas with a lot of pf population
- In industrial areas and factories
- Scenic places
They are also used to supply power from the overhead power posts to the consumer properties.
Depending on their construction and the voltage rating, the underground cables can be very expensive to manufacture.
Difference Between Underground Cables and Overhead Cables
Overhead Power Lines
Steel towers or wooden poles hold the overhead electricity cables up. They are very common. You will find them in rural areas and on roadsides. They are ideal for covering long distances.
The underground electricity lines are laid under the ground. They are more common in urban areas.
Advantages of Underground Cables
There are many advantages to using underground cables:
- In the underground cables, there is less chance of developing faults.
- They have smaller voltage drops as compared to overhead cables.
- They don’t require frequent maintenance and if they do, it is not as expensive.
Types of Underground Cables
There are two ways to classify the cables used in underground lines:
- Depending on the Voltage Capacity
By Voltage Capacity
|LT cables or Low-tension cables: maximum capacity of 1000 V||Belted cables: Maximum voltage of 11KVA|
|HT Cables or High-tension cables: maximum of 11KV||Screened cables: Maximum voltage of 66 KVA|
|ST cables or Super-tension cables: the rating of between 22 kV and 33 VK||Pressure cables: Maximum voltage of more than 66KVA|
|EHT cables or Extra high-tension cables: the rating of between 33 kV and 66 kV|
|Extra super voltage cables: maximum voltage ratings beyond 132 kV|
EMF Radiation from Electricity Lines
To understand the EMF radiation that emits from underground cables, we must first talk about the EMF radiation from basic electricity lines.
Essentially, other than construction differences, the power cables perform the same function. They transfer electricity from one place to another. And, as we have talked about many times, when an electric current passes through a wire, it produces electromagnetic fields.
Likewise, when electricity passing through underground cables also produces electromagnetic fields. These electromagnetic fields are:
- Low-frequency fields
- Non-ionizing radiation
The electromagnetic fields that power lines produce have very low frequencies. They are like the EMF radiation that comes from our everyday electrical devices.
Effectively, they are much less damaging than the other types of electromagnetic radiation (ionizing radiation like microwaves, gamma rays, etc).
However, even when they are low frequency, the electromagnetic radiation that comes from power lines is much higher in energy.
In underground power lines, when an electric current passes through the cables, it also produces low frequency and non-ionizing radiation. Here is how this happens:
The electric charges in the underground cables produce electric fields.
And, when the electric current starts flowing through the wires, it produces a magnetic field.
Therefore, low frequency electric and magnetic fields are found close to cables and power lines (both underground and overhead power lines).
So, how strong is that electromagnetic field that the power cables produce? The strength of the electromagnetic field depends on the amount of electric current.
A simple formula is that the strength of the electromagnetic field is directly proportional to the amount of electric current that passes through the power cables. However, the strength of the EMF and its effect reduces greatly as you increase the distance between yourself and the source of the electromagnetic field.
So, a simpler solution that seems to work with power lines is:
- Increase the distance between yourself and the power lines (or any other source of EMF around you).
- To limit the time that you spend in the vicinity of the source. Since the duration of the exposure is as important as the proximity to the source when determining the effect of EMF radiation.
However, with underground cables the problem is different. If underground cables are already under your property, you cannot change the distance (at least not easily). So, let us talk in detail about the underground electric lines and their electromagnetic fields.
EMF Radiation from the Underground Power Cables
Underground cables aren’t as common as the overhead power lines. One of the main reasons is that they are more expensive than other power cables. Generally, you can expect the cost of underground cables to be three to four times higher than the cost of overhead cables.
First, like the overhead power lines, the underground wires also produce a minimal level of electromagnetic fields. At the low levels of the electromagnetic field, there is no need to be concerned about the EMF radiation levels.
Depth & Distance
When installing underground cables, depth is an important factor. The easy formula here is that the distance is inversely proportional to the strength of the electromagnetic fields.
If the depth of the underground cables is greater, the strength of the EMF radiation reaching you will be lesser.
Moreover, the underground cables are way under the ground with layers of soil and asphalt. These layers add distance and a cushion between the electromagnetic fields and radiation, and you.
The distance and layers solve the problem if you are concerned about the electric field. However, the magnetic field radiation is still a concern. Even at the distance, the magnetic field coming from underground cables is quite high.
Construction of Underground Cables
In an underground cable, there are individual conductors. These conductors are insulated individually. This allows them to be close together. As a result, the electromagnetic fields coming from the wires in a cable cancel each other.
Therefore, the total electromagnetic field that they produce is very low.
However, if they are installed too close to the ground, the fields will still be higher. Therefore, it recommended making sure the underground cables are buried deep in the ground at the time of installing.
Do underground cables emit more EMF radiation than overhead power lines?
Both the overhead lines and underground cables produce electric and magnetic fields. Since the electric charges in the wires run in opposite directions and most of the field cancels out.
The problem is then left about the magnetic field. The magnetic field that the power cables produce is high-frequency and strong.
The underground cables produce very high magnetic fields. However, when comparing the strength of the magnetic field from overhead cables and underground cables, the ground-level magnetic fields from the underground wires falls rapidly with distance as compared to that from overhead lines.
How strong is the EMF radiation from the cables in underground tunnels?
Sometimes, instead of burying the cables in the ground, the underground power lines are placed in a tunnel. These tunnels are placed 20 to 30 meters under the ground.
In the case when the underground cables are in a cable tunnel, the conductors are not close and cannot be approached closely. As a result, the magnetic field is very low.
Compared to the overhead power lines, the magnetic field from underground cables tunnels is far lower.
How Strong is the EMF radiation from Underground Cables with Multiple Conductors?
The magnetic fields coming from underground cables with multiple conductors are complicated.
In some cases, the underground cables have more than one circuits. These circuits are placed under the ground very close to each other. In this case, each circuit requires two groups of conductors.
The resultant magnetic field depends on two factors:
- Number of the group of conductors
- Phasing order
For each phasing, the magnetic field varies. The lowest resultant magnetic field is noticed in an alternating phasing.
How much EMF radiation do Single-Phase underground power cables emit?
Usually, the high-voltage underground power cables that we use, come with three-phases. However, in areas below and around the railways, single-phase underground cables are used.
Practically, the electromagnetic fields that the single-phase underground cables use are the same as three-phase underground wires.
However, the conductor spacing is variable in single-phase cables. Moreover, the loads they carry are also very different. Therefore, the only way to check the EMF radiation from single-phase underground cables is to specifically calculate it.
Are Underground Cables Safe?
If your property is on or near underground cables, are you safe? Other than EMF radiation, certain factors can make underground cables unsafe.
When digging, it is possible to get an injury from the underground power lines. In some cases, someone can even get an electric shock.
Some high-voltage cables have oil. They can ignite easily because of the oil. Remember that electric fires are disastrous. The san spread to other areas fast and may reach nearby gas lines.
To avoid such accidents, it is necessary to take precautions. In case you need to dig, make sure to follow the Code of Practices that the Government provides.
Here are some tips to help you stay safe:
Check the Cable Records
When starting a project that needs digging, check the cable records of your property. Mark the locations that you need to avoid. During the project, keep the cable records around at all times.
Cable Locating Devices
Another way is to use cable locating devices. With the cable plans in front of you, you can use a suitable cable locating device. Together both of these ways will help you to find the exact location and position of the underground power cables.
How dangerous is the EMF radiation from underground cables?
The EMF radiation levels of an underground power cable depending on the voltage. A high-voltage current flowing through the cable will produce high energy fields. The high-intensity radiation can affect the health of people living in the areas of exposure for longer times.
Another determining factor is the distance of the source from you. the wires running deep under the ground will be producing very low-impact fields. These fields are not strong enough to cause any health problems.
However, if the underground cables near your property are not done properly, and is not deep enough, it may cause many problems. The problems can be greater for children and people suffering from electromagnetic hypersensitivity (EHS).
The following are the issues that according to the World Health Organization WHO, can happen as an effect of the EMF radiation from underground cables.
- Headaches or Migraines
- Fatigue or Tiredness
- Nausea and Anxiety
- Sleep Disturbance and Insomnia
- Irritation or burning skin
- Skin Rashes
- Muscular pain
Since a lot is still unknown and under speculation, we cannot fully say they are harmless or harmful. Some studies claim that EMF from power lines can cause cancer. Others counter them by claiming that these levels are not high enough to cause any problems.
What do we do then? I would say (and what I am so enthusiastically doing) educate ourselves and others.
Since the electromagnetic field that the underground cables produce is very low, I will say you don’t have to worry about its impacts. The EMF radiation from underground cables can be harmless if the cables are deep enough in the soil.
Take a look at the cable records to find out about their location and position. However, the intensity of EMF radiation from the underground cable is lower than overhead lines. Therefore, they may be a better choice.