On 1 July 2016, the "Control of Electromagnetic Fields at Work Regulations 2016" came into force in the UK, implementing new exposure limits for occupational exposure to electric and magnetic fields (EMFs). National Grid has implemented these Regulations in full from that date. This page is designed for National Grid staff, to answer questions about what we have done and how it might affect you. Or jump straight to our formal statement of compliance.
If you have found your way here and you are not working for National Grid, don't worry, there's nothing confidential here!
What were we doing before these Regulations came in?
Up to 2016, there has been no legal requirement to comply with exposure limits. But we did so anyway, voluntarily, because we thought it was the responsible thing to do to protect our staff. It is written into the Corporate Public Position Statement.
The limits we were complying with were the 1998 limits from the International Commission on Non-Ionizing Radiation Protection (ICNIRP).
In 2013, the EU passed a Directive, requiring member states to implement the more recent 2010 limits from ICNIRP within 3 years. That has been achieved in the UK by the Control of Electromagnetic Fields at Work Regulations 2016. So, from 1 July 2016, we have been following the newer 2010 limits rather than the older 1998 limits, and doing so is no longer voluntary but a legal requirement.
What are the new limits?
The new 2010 limits, now included in the 2016 Regulations, are not greatly different from the older 1998 limits - pretty much the same for electric fields, slightly relaxed for magnetic fields.
The structure of the limits is quite complicated, with Low Action Levels, High Action Levels, Sensory Exposure Limit Values, and Health Exposure Limit Values. National Grid (along with the rest of the electricity industry) normally complies with the High Action Levels. These are:
- electrc fields: 20 kV/m
- magnetic fields: 6 mT (18 mT for exposure to limbs only)
The vast majority of our activities comply, or can be brought into compliance, with these limits. We are reserving the ability to follow the Health Exposure Limit Values in special circumstances, primarily where the exposure is non-uniform over the body (e.g. live-line work) or where the field is in a direction that doesn't affect the body so much (e.g. climbing a tower body past live circuits, where the exposure is mainly horizontal across the body rather than along it). But normally it is the High Action Levels that we follow.
How have we implemented these limits?
Up to 2016, although we were following the exposure limits, because this was voluntary, there wasn't a formal governance structure around this. We have now created a formal governance framework consisting of:
- a new SHE Procedure setting out all the key requirements (NGUKSHE237 "Management of Electric & Magnetic Fields")
- a Risk Assessment, looking at every work practice and plant item in National Grid and assessing them for compliance
- an Information Sheet with the key information that staff need to know
- appropriate entries in other documents, such as NGTS1 which requires new equipment to be designed so as to be compliant.
You can find the Procedure, NGUKSHE237, in the Intranet. The Risk Assessment and the Information Sheet are on our formal Compliance page.
What work practices or plant items does this affect?
The top-line message is that it is the Company's responsibility to ensure that everything National Grid does is compliant. This compliance process is overseen by National Grid's EMF specialists. You, as a member of staff, don't need to assess compliance or control your exposures for yourself.
However, we understand that you will probably want some assurance that your particular work area or work practice has been properly assessed. So all the evidence and assessments are available (in great detail!) in the Risk Assessment, available on the formal Compliance page.
The Risk Assessment concludes that all our plant items and work practices are compliant. In some cases, they are compliant only because we put in place restrictions to ensure this. For instance, some SVCs have a fence around the reactor coils. The restrictions are different for the new limits compared to the old. In fact, because the new limits are slightly relaxed for magnetic fields compared to the old, the restrictions have relaxed as well - for example, the area fenced off around SVC coils has reduced in size considerably. But, one way or another, we ensure that every activity is compliant.
What if I have a pacemaker or other implanted device?
Some pacemakers, and other Active Implanted Medical Devices (AIMDs) or Body Worn Medical Devices (BWMDs) - defibrillators, cochlear implants, insulin and hormone pumps, neurostimulators, etc - can, in principle, be subject to interference at levels below the exposure limits that apply to staff in general. That is, there could be interference at levels that staff in general are allowed to be exposed to and that can be found in some parts of National Grid operational sites. Passive implanted devices - rods, pins, nails, joints etc - are absolutely fine, and will not be subject to any effects.
All AIMDs are required to be immune from interference up to an electric field of 5 kV/m and a magnetic field of 100 µT (these generic immunity thresholds are the reference levels for the general public). Those levels can be exceeded in most electrical environments, certainly in substation compounds. But, crucially, most individual devices are immune to much higher levels - it depends on the particular device and what settings have been applied to you as an individual. So most people with these devices will still not experience interference, even in say a substation, despite the field being above the generic immunity thresholds.
If you have an AIMD, and you have been doing your job without experiencing any interference, then the first message is, don't panic. If you have not been experiencing interference, that probably means that your device is immune at the levels you are encountering.
The second message is that all offices are below the generic immunity thresholds so should be fine, and likewise all construction sites unless there is live transmission equipment in the vicinity. Passing underneath an overhead line at ground level should be fine too. So it is only with substations, climbing towers, and cable tunnels, and similar work environments, where the issue arises.
But the possibility of interference is, clearly, something we have to take very seriously. So, if you work in one of these environments, and you have not already done so, you should notify your line manager that you have an active implanted device, and either they or you should notify Occupational Health. We can then do an assessment of your work environment (if possible, obtaining information about the settings on your device from your doctor or the manufacturer).
It may be that there will need to be some restrictions on where you go. But we try to avoid this, and if restrictions are necessary, we try to make them as precise as possible and to avoid blanket restrictions.
We have a lot more information about interference with medical devices elsewhere on this website.
What if I am pregnant?
The exposure limits are designed to prevent all effects of EMFs in people. There is actually no strong scientific evidence that either the pregnant mother or the unborn child is any more sensitive to EMFs. So you can, if you wish, carry on doing exactly the same job during pregnancy as far as EMFs are concerned. And if you've been exposed to high fields during pregnancy, there is no need to worry.
However, there is an entirely appropriate feeling that the unbord child should be given special protection, and it is possible, if somewhat speculative, that the developing foetal nervous system could be more susceptible. So, in a spirit of providing reassurance and applying an element of precaution, National Grid has a long-standing policy of allowing pregnant women to choose, if they wish, to comply with the general public limits rather than the occupational limits for the duration of their pregnancy. This hasn't been particularly well publicised, and we are taking advantage of the new procedures to make it better known. So, when you notify your manager that you are pregnant, have a conversation about the EMF limits. (As with implanted medical devices, this applies only to operational sites such as substations and cable tunnels - offices are already compliant with the public exposure limits.)
What if I am site manager or occupier?
If you have responsibility for a site, or simply if you are wondering about admitting visitors to a substation:
You do not need to worry about compliance of the equipment with the exposure limits in general. National Grid has assessed this centrally and if any restrictions are needed on your site we have let you know (this applies to just seven sites with one particular design of SVC). The details of these assessments are available in the Risk Assessment which you can find on our formal Compliance page. But if there's a particular plant item or arrangement of plant items that you are concerned about, do please still contact us, we don't want to miss anything.
If someone arrives at your substation or other site with a pacemaker, a defibrillator, or other active implanted medical device, there is a theoretical possible risk of interference, and if they have not already been assessed you should seek advice before allowing them into a high-field area such as the HV compound or a cable tunnel. If they are a contractor, it is their own employer's responsibility to have performed a risk assessment. If they are a National Grid employee, they should already have notified Occupational Health, an assessment should have been performed, and any necessary restrictions agreed. So it should be very rare that anyone with an implanted device turns up unexpectedly. But if that does happen, there may need to be a delay while advice is sought from Occupational Health or EMF Specialists - we cannot take the risk of letting someone whom we know has a medical device into an area where interference is a possibility unless that risk has been assessed.
But you don't need to ask every single visitor whether they have a pacemaker. The primary control here is that any person with an implanted medical device will themselves be alert to any possibility of interference in an electrical environment. That means there are several things you do NOT need to do:
- we are not placing warning signs at all substation entrances - the people who it affects will be aware of the risks without needing warning.
- if your substation is one where a visitor has to cross the HV compound to reach reception, they will be aware of the risk, and that is a risk we judge to be acceptably low.
- you do not need to include anything about EMFs or pacemakers on a site hazard plan.
Remember, there are no instances we are aware of of anyone coming to any harm in this way, over a period when pacemakers were more prone to interference and any controls even lighter than they are now. But when you are performing a site induction for visitors or contractors you should mention the possibility of interference with implanted medical devices just as you would mention any other hazard.
What about Brexit?
The UK Control of Electromagnetic Fields at Work Regulations 2016 came into force before the UK left the EU (in fact they came into force even before the referendum ... just....) So, regardless of the fact that the driver for these Regulations was an EU Directive, they now form UK law and will remain in place once the UK leaves the EU.
It's possible that the UK Government could decide to repeal these Regulations following Brexit. Or they might decide to take the easy option and just leave them in place. But either way, National Grid was complying with the relevant exposure limits before the Regulations came in, and we'll continue complying with them even if the Regulations are repealed. Complying with exposure limits is something we do because we believe it's the right thing to protect our staff, not because we're forced to by legislation.
Questions and comments?
If you have questions and comments, please direct them to the EMF Helpline by email in the first instance: EMFHelpline@nationalgrid.com. That will allow us to direct them to the right people.