Substation Health Risks

Substation EMFSubstations emit a low-frequency electromagnetic radiation (EMR) which creates an electromagnetic field (EMF). This EMF has two components, an electric field and a magnetic field.

Don’t worry too much about the electric field. It lacks power to penetrate the substation walls.

But the magnetic field goes right through bricks, concrete, or a human body. It cannot be shielded. This magnetic field is thought to be responsible for the health risks of low-frequency EMF.

People who live really close to a substation are right to be concerned about this radiation, but the risks are generally misunderstood.

What kind of substations produce magnetic fields?

There are different kinds of substations. Some are huge national grid installations  (as much as 100 metres across, or more) and others are only slightly smaller (tens of metres across). They are normally situated far away from buildings where people live or work.

The substations that cause concern to property owners and residents in the U.K. and elsewhere are seldom larger than 5 metres across. They are found every hundred metres or so in suburban districts. (In the US they may be called distribution transformers.)

These substations may be sited very close to buildings, including houses, or may share a common wall with them.


Sometimes they are even contained within large blocks of flats or other substantial buildings. Such built-in substations may produce a powerful magnetic field in rooms where people live or work.

Magnetic field radiation is emitted by all sub-stations. Though non-ionising, it is nevertheless dangerous to health. For more information, see EMF Health Dangers.

What do substations look like and what are they for?

Stand-alone substations in the U.K. are usually rectangular structures, either open (and fenced) or closed, like a shed. Or they may be brick-built.

Whatever the type, they are not known for their architectural flair, although there are some exceptions – like this one!

Though not pretty, they are useful. Their main purpose is to transform electricity – from the higher voltages used for cross-country power transmission, to the lower voltage used by consumers, for example 240V in the UK, or 110V in the US.

Inside the substation there are connections, switches, cabling and a transformer. The substation should have a prominent sign on the exterior, discouraging unauthorised entry. In the U.K. the sign proclaims, rather dramatically, “Danger of Death.”


This warning is designed to stop people from entering the substation and electrocuting themselves. It has nothing to do with EMF risks. Nevertheless, the warning creates public unease about substations.

There is another kind of substation – pole-mounted, or slung high between two poles, usually in the street. These generally serve a small number of properties. They seldom pose a hazard to nearby property, as detectable EMF often extends only 3 metres.

With all kinds of substations, the EMF is strongest right next to the installed equipment, then it fades away rapidly as distance increases.

Substations Emit Radiation

Magnetic field EMF is emitted whenever an electric current flows through a conductor, but it can be opposed by current flowing in the opposite direction in an adjacent conductor. (This is the key to designing electrical equipment which produces low EMF.)

Not all the equipment inside a substation is equally hazardous, from an EMF perspective. Usually the transformer emits the largest amount of radiation. The transformer is generally the largest piece of equipment you can see in a substation – if you can see inside at all.

Some older substations still have their original cabling and equipment. These tend to emit more radiation than newer ones. (Electrical engineers know how to design equipment that emits less EMF, but decades ago few people worried about it.)

Cabling and switchgear inside the substation are generally mounted on one of the side walls. The transformer is nearby, usually floor-mounted. So the EMF outside one wall of the substation may be stronger than from the opposite side.

The stronger EMF will also penetrate further.

U.K. Substation Safe Distance

Substation Safe Distance


Usually, the detectable magnetic field from a substation extends between 3 and 8 metres away. Some are stronger than others, and in rare, exceptional cases, EMF may extend to about 15 metres. Outside of the detectable magnetic field, there can be no health effect from the substation.

The magnetic field will reach its peak during periods of peak electricity usage (usually around 8 am and 6 pm in residential districts) and will generally be lower at night.

Cables into and out from the substation are generally routed along the pavements. They may be overhead or underground.

These cables can also give rise to a magnetic field, which may affect nearby properties, perhaps a small portion of the garden, or sometimes part of a room within the house.

Every house with electrical power is supplied through a cable, even properties which are far away from their nearest substation. So there is always a possibility of a house being affected by EMF, either from its own supply cable or from a neighbour’s.

Substations connect to each other, together serving a wide area. Sometimes these connections are made so that live current flow takes one path from substation to substation, and neutral current flow takes another. This is not against current regulations (ha!) in the UK.

Where it does occur, the unbalanced current flow can give rise to a widespread magnetic field, possibly affecting several streets, and all the properties within them.

In all cases, an EMF check can be made with a low-frequency EMF meter.

Selling a Property Near a Substation

Substation EMF RiskAwareness of the potential EMF hazard from substations appears to be increasing in the UK, to judge by the number of EMF survey requests we receive from property buyers and sellers.


Nearby substations tend to put off some potential buyers. This reduces the demand for the property, and may have an unfavourable effect on its market price.

If you are selling a property near a substation, you can expect that MOST buyers these days WILL notice the substation, at some stage during the buying process – or have it drawn to their attention in a survey report.

So our advice to sellers is to instruct the agent to be upfront with prospective buyers about the substation, and have a professional EMF survey report showing how the property is affected by substation EMF.

In most cases that report will show no effect, in which case it will put the buyers’ fears to rest.

In some cases there may be an EMF effect from the substation. In those cases, the EMF impact will almost certainly be confined to certain rooms or garden areas, and be less extensive than buyers fear.

For maximum credibility, we recommend that an EMF survey should be done by an independent EMF assessor, not by the power company concerned.

The report should include actual magnetic field measurements at various locations within the property, quantified in milligauss or microtesla, not just as percentages of the legal limit.

Buying a Property Near a Substation

In our experience, buyers tend to overestimate the EMF affect of a a nearby substation on their proposed property. But as the buyer, you can’t afford to guess about a matter so important to your health.

So if you are interested in buying a property near a substation, first check it out for radiation (or have it done for you.)


If there is no EMF, there is no health risk – but you may be able to pick up a good house at an unusually low price.

Here are six good reasons for requesting an EMF survey – even if the house is out of range of the substation’s EMF

  1. The survey will show whether or not the substation creates any EMF within the property
  2. A survey may bring to light other EMF (low-frequency or radio-frequency) problems affecting the property
  3. The survey report will help you to assess potential health risks of any EMF found
  4. A survey will help you decide if you still want the property, and put your mind at ease if no EMF problems are detected
  5. EMF survey results may influence your perception of the property’s value, and what you are willing to pay
  6. Finally, if you do buy the property, you can keep the survey report for use when you become a seller.

Substation EMF – Safe Level

We consider a property to be EMF-safe if the maximum magnetic field measurement in any location where someone may spend several hours a day, does not exceed 0.5 milligauss (o.05 microtesla).

But 1.0 milligauss (0.1 microtesla) is also acceptable for all but the most vulnerable people.

Vulnerable groups include the elderly, those suffering from chronic illness, pregnant women, infants and small children, as well as people who are electro-hypersensitive (EHS).

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