# Quick Calculation of Magnetic Flux Density in Electrical Facilities
## 1 Introduction
In line with this, recommendation VI says: \"Member States, in order to enhance knowledge about the health effects of electromagnetic fields, should promote and review research relevant to electromagnetic fields and human health in the context of their national research programmes, taking into account Community and inter-national research recommendations and efforts from the widest possible range of sources\". In this sense, the Spanish government (as in other EU countries), with the regulation of high voltage electrical installations (RAT) [15], has imposed an obligation to study the magnetic fields produced by electrical installations to guarantee that the exposure limits regulated by [11] are not exceeded and to enhance the design of new facilities to minimize the magnetic field emissions. These studies would allow engineers to improve their knowledge about the possible incidence of magnetic fields produced by electrical facilities in the environment. The RAT establishes in the Complementary Technical Instruction (ITC) number 20 (ITC-RAT 20 Projects and preliminary projects) that the memory of high-voltage facility projects must include a study of magnetic fields in their surroundings. It is necessary to have more information to improve the knowledge about the incidence of these fields on some diseases (such as childhood leukemia), as several authors explain in studies that try to improve the apparent correlation between the detected cases (which are very scarce) and the odds ratio (close to 2) that some epidemiological studies have obtained [16]. Some recent meta-analyses propose the thesis of a non-accidental correlation between the exposure to MFDs of more than 0.4 \(\upmu\)T and the risk of childhood leukemia (odds ratio close to 2) or acute lymphocytic leukemia (odds ratio 2.43) [17]. Therefore, this value of 0.4 \(\upmu\)T is often considered as a precautionary level for this disease. The need to deepen the analysis to achieve greater consensus is highlighted by many researchers [18]. Many recent studies try to correlate the risk of cancer and the proximity to high voltage lines [19; 20]. To date, the results are still fairly uneven, although it seems that the proximity to these facilities increases the risk. Other studies have tried to correlate the risk of cancer with the proximity to high-voltage underground lines, concluding that there is no increased risk in this case [21]. Additionally, some studies have also been conducted on the possible influence of the proximity to high voltage facilities on neurodegenerative diseases, but the results have not found any evidence [22]. There are not many recent advances about the cause effect relationship between magnetic fields and diseases. Nonetheless, the research remains active among the scientific community, as can be seen in [23; 24]. One of the main disadvantages of epidemiological studies is the low number of individuals included in control areas and the low incidence that these diseases have on the general population. But there is an issue that has not been satisfactorily resolved to date: if the cause of the increased risk of certain diseases is the magnetic field (not the electric one), that effect should also be observed in locations where the magnetic field is produced by low voltage facilities. On the contrary, if the only measurable influence is observed in the proximity of high voltage lines, the cause cannot be attributed exclusively to the magnetic field. Indeed, although both fields (magnetic and electric) are related by electromagnetic theory, at very low frequencies they are not coupled at the distances where people are exposed. In these cases, the magnetic field can be studied as a phenomenon that can be considered independent of the electric field of the system that produces it. In urban environments it is very common to find facilities such as distribution transformer substations (DTSs) next to inhabited buildings or very close to dwellings.