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Electric and magnetic fields and health

index/glossary | EMFs At A Glance | EMF The Facts (pdf)
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
    • Substations
      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
      • Distribution substations
      • Final distribution substations
        • Indoor substations
    • Transport
      • EMFs from electric trains (UK)
      • EMFs from cars
    • Appliances
    • Electricity meters
      • Smart meters
      • Traditional meters
    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
    • Types of research
    • Epidemiology
    • Animal and laboratory experiments
    • Mechanisms
    • Specific studies
      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
    • EMF measurement and commercial services
    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view
You are here: Home / Affected by a new power line or substation?

Affected by a new power line or substation?

Is there a new overhead line or substation being proposed close to where you live? Do you have concerns about potential health effects of these proposals?

If you are in this situation the information included in this section may answer some of your questions. If you need more information on EMFs then you can discuss your specific questions with a professional EMF Advisor by contacting the EMF Helpline. You may also find our booklet EMF The Facts helpful.

Am I exposed to EMFs already?

Yes.  Anything which uses electricity produces electric and magnetic fields. This includes our household wiring, appliances and the local electricity distribution system. All of these contribute to background electric and magnetic fields in homes, which for electric fields is around 20 V/m and magnetic fields between 0.01 – 0.2 μT.

more on sources of exposure and levels of fields

And will a new overhead lines or substation increase my exposure?

 Yes, if it's close enough.

Both overhead lines and substations produce electric and magnetic fields:

  • Substations

For high voltage National Grid substation, you would need to be within metres or maybe tens of metres of the perimeter to get an elevated field. National Grid would always try to maximise the distance of a proposed substation to homes, and it would be rare be that close in a rural setting, but it could happen in an urban setting. But you would probably be getting a higher field from the lines or cables entering the substation.

 More on substation exposures

  • Overhead lines

The electric and magnetic fields from an overhead line would depend on its voltage, the current it could carry, and its design. EMF from overhead lines are highest directly underneath the wires and reduce as you move away from the wires.

Typically an overhead line operating at 400 kV would reduce to the level field found in other homes within about 100 m of the overhead line.

More on overhead line exposures

This distance would be less for lower voltage lines.

More distances for different voltages and different field levels

All sources - both overhead lines and substations - comply with the relevant exposure limits - see below.

Why is there concern?

Over the last 40 years there have been suggestions that magnetic fields, at the levels produced by overhead lines, may cause diseases, principally childhood leukaemia.

 The evidence for this comes from epidemiology studies (the study of statistics about disease), which have found a statistical association - an apparent two-fold increase in leukaemia incidence, from about 1 in 24,000 per year up to 1 in 12,000 per year, for the children with the top half percent of exposures. To set against this, mice and rats don’t seem to get disease when we expose them in the laboratory. So overall the science is uncertain.

more on the scientific evidence

 The evidence is strong enough for magnetic fields to be classified by the World Health Organization as "possibly carcinogenic". But because these studies only show statistical associations and do not demonstrate causation, and because the evidence from the laboratory (biology and theoretical science) is against, the risk is not established, it remains only a possibility.

more on what expert bodies have said

What exposures are acceptable?

The decisions on what exposures are acceptable is made independently of National Grid and the electricity industry.

 The UK Government at a national level set exposure guidelines for EMFs and the electricity system complies with this, including new equipment. The limits are designed to prevent all established effects of fields on the body.

more on policy in the UK

The limits we follow in the UK stem from an international body ICNIRP and are the same ones set by the EU and used in many other countries round the world.

more on exposure limits

The guidelines for public exposure are expressed in volts per metre (V/m) for electric fields and microteslas (µT) for magnetic fields. We ensure that all power lines comply with these values even directly underneath them – there is no need for any extra “safe distance” between a property and an overhead line or substation to achieve compliance, and there are no restriction on how close a property can be to a power line or substation.

Exposure limits - the numbers

The exposure limits have "reference levels" and "basic restrictions".

Often it’s sufficient just to look at the “reference levels”:

  • Electric fields: 5 kV/m
  • Magnetic fields: 100 µT

But the actual limits are given by the “basic restrictions” which are a bit higher:

  • Electric fields 9 kV/m
  • Magnetic fields: 360 µT

These apply in areas where people spend significant periods of time.

more on the numbers in detail

So will the overhead line or substation be safe?

All overhead lines and substations comply with the exposure limits, and remember, these exposure limits are set by independent international experts, not by us in the electricity industry – we just make sure all our lines comply with them.

 There is some evidence of a possible risk of childhood leukaemia below these exposure limits, at levels produced close to some overhead lines. This is just a possibility – we’d probably say the balance of evidence is against health effects – and it’s not considered strong enough evidence to restrict such exposures.

But it is for each person and family to decide for themselves how they you feel about this based on the evidence.

 

Latest news

  • New publication on cancer incidence from the UK electricity industry Cohort Study August 27, 2019
  • How has the reported risk for childhood leukaemia changed over time? February 11, 2019
  • Media stories about microshocks in children’s playground September 10, 2018
  • New studies on leukaemia and distance from power lines June 1, 2018
older news

Contact Us

To contact the electricity industry’s EMF Unit Public Information Line (UK only):
telephone 0845 7023270 or email [email protected].

See Contact us for more contact details including our privacy policy.

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Specific questions

  • Affected by a new power line or substation?
  • Building or developing near a power line or substation?
  • EMF measurement and commercial services
  • Microshocks
  • Pacemakers and other medical devices
  • EMF policy in the UK
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Navigation
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
    • Substations
      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
      • Distribution substations
      • Final distribution substations
        • Indoor substations
    • Transport
      • EMFs from electric trains (UK)
      • EMFs from cars
    • Appliances
    • Electricity meters
      • Smart meters
      • Traditional meters
    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
    • Types of research
    • Epidemiology
    • Animal and laboratory experiments
    • Mechanisms
    • Specific studies
      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
    • EMF measurement and commercial services
    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view