Demands on our hospital estate electrical infrastructure and the role of an effective AP

As one of the largest consumers of electricity in the country the NHS is exceeding its reserved capacities and putting further strain on an already stretched electrical supply network.  Kevin Furey, Electrical Portfolio Manager at Eastwood Park examines the issues facing the NHS in maintaining sufficient and safe electrical supplies that cope with NHS needs for the future.

The UK National Grid network is now operating with the lowest reserve capacity in living memory, mainly due to old and out dated power stations.  Power station closures and network breakdowns as well as the fact that when the network was constructed it did not allow for sufficient future spare electricity capacity to cover modern living demands. The National Grid is typically running at around 5% reserve capacity during winter months; with an exceptionally severe or long winter this could drop still further, which will have the on-going effect of pushing the nation’s electricity supply to a critical level, potentially leading to power cuts becoming inevitable.

With the installation of power thirsty imaging equipment and other new technologies growth and expansion of NHS facilities and new builds, these are all increasing the strain on an already overstressed supply network.  If the NHS hospital expansion and new build programme continues at the present rate many hospitals could be at risk of power losses, due to the increased loading put on the network.  Potentially this could cause problems in particular on some of the older sites, which have a poor electrical infrastructure with ageing switchgear or lack of adequate generation or UPS systems for patient critical areas.

In addition, these future plans for hospital redevelopment or new builds are proceeding despite currently the fact that they are exceeding their agreed electrical capacity. In some cases, the capacity charges imposed by the supply companies are over and above that which has been set with the network operators.    

With new high voltage sub-stations now costing between £200k and up to £2m depending on the level of resilience and standby power and protection systems required, serious consideration should be given to the infrastructure under any strategic development plans, as it may be necessary to install a High Voltage network to a hospital currently running on a Low Voltage supply, this will have to be factored into the overall costs of the project.  

HTM requirements

One of the requirements of the Health Technical Memoranda (HTM’s) is to eliminate as many of the single points of failure to hospital electrical systems as is possible.  This is best achieved by moving single points of failure as close to the point of use as possible and having adequate levels of alternative power available to cover potential failures.

Achieving this in reality is not always so simplistic, especially due to the nature of the individual systems found across varying ages and levels of complexity of electrical systems within the NHS estate.  The main methods of achieving this are dependent on the type and size of the hospital and the need for critical patient care.

This increased complexity of hospital electrical systems is giving rise to the need for training on these varied systems.

More and more estates, due to their size, are now encompassing their own High Voltage electrical networks, this requires the system to be managed safely under the procedures set out in HTM 06-03 which states the need for at least two members of the estates staff to be trained as Authorised Persons to operate the system. This is fundamental to the safe operation of the high voltage network and to ensuring the system’s effective resilience and the quick restoration of the supply in the event of the system failing due to a fault.

There are differing degrees of resilience set out in HTM 00, providing various levels of supply continuity dependent on clinical risk and type of care facility.

This again galvanises the need for adequate training of the maintenance teams to deal with the increasing complexity of the electrical systems found across the estate.

As previously intonated many sites now have their own high voltage network as well as high voltage generation, or perhaps a combined heat and power system, acute sites will have UPS/IPS systems for HDU’s imaging departments and theatres., Also medical electrical systems which historically were covered under the MEIGaN rules are now absorbed into BS7671 17th edition of the wiring regulations, all of which have a requirement for either safe system of work training under HTM 06-03 for high voltage systems or HTM 06-02 for the low voltage networks.

These critical systems have historically been maintained by specialist external contractors or the manufacturers, with the onsite staff only having a very basic rudimentary knowledge or no understanding of their operation and maintenance at all, which causes an issue when they fail out of hours and only the onsite maintenance staff are onsite to attempt to repair or bypass these systems often with catastrophic results.

Your role as CP & AP

The NHS Competent Person / Authorised Person training regime adopted by most Trusts should now deal with the operation and isolation of these systems as a core element of the course, as should the operation of the other standby power supplies whether they are generators or uninterruptable power supplies from desktop units to large complex stand- alone systems.

Many sites have either LV or HV generating sets which either carry the entire site load or essential supplies only. These need to run regularly and “black start” runs carried out to ensure that in the event of a power failure these systems will take up the load and just as importantly transfer back once power is restored, this requires the onsite AP to ensure this is carried out seamlessly, again this will require a need for training on their operation.

One of the crucial areas again with regard to continuity of supply is the increasing age and levels of maintenance of both the sites low and high voltage switchgear

A good deal of the supply switchgear is now getting to the end of its useful life or incapable of complying with current legislation or more importantly operational needs.

The low voltage side of the estates electrical supply network is becoming more and more complex with the requirement of essential and non-essential loads and the ability to be cross coupled as required.

As mentioned previously most of the ageing switchgear was manufactured to comply with the needs and requirements of the time, under HTM 06-02 safety guidance to work on this switchgear may now require the whole system to be isolated to allow a small part to be worked on as it does not conform to IP2X requirements, this could mean large areas or the whole hospital being shut down to effect a quite trivial repair.

One of the areas that also needs highlighting is the electrical testing of medical locations, historically a difficult field to deal with, not only due to the notorious problems involved in shutting down areas to carry out this task, but the need for adequately qualified test engineers and the ability of the electrical Estates Officers being capable of understanding the results and dealing with the remedial works generated.

Due to operational or financial reasons electrical condition reporting is generally being carried out by external specialist contractors, however even small works that are being undertaken by the in house electrical teams, need to be covered by completing a minor electrical works certificate. Some Trusts are embracing this but others are still yet to.

Where these works are being contracted out the AP on site needs to be aware of who is working on his site.  Also ensuring that they are assessed for competency and made aware of the procedures laid out in the HTM’s,that the safe system of work is being followed and test results understood.

For all minor alterations or additions to an existing circuit the crucial requirement of this is to carry out a basic earth fault loop test to ensure the circuit is safe to both work on and more importantly safe to re-energise.

This test should be carried out both prior to carrying out the repair and also after the repair has been completed.  This is to ensure that both polarity and disconnection times are correct and the  earth fault loop test readings are commensurate with figures quoted in BS7671 Amendment 3, to this end the acceptable earth fault loop impedance figures are printed on page 37 of the current HTM06-02 safety handbook, although not to the new revised figures of amendment 3. This will need to be addressed at site level.

Your HV network & safe operating practice

As previously mentioned many of the larger hospital sites have their own high voltage network, varying in complexity from simple radial supplies from the DNO to a supply transformer to extremely complex closed ring layout with all the inherent protection / supervisory systems all of which need to be regularly tested and maintained.

These systems vary from being under the control of the supplier to the on site NHS high voltage AP’s,- this is where we need to address the issues of suitably trained and competent in house staff.

Maintenance of these systems is paramount to ensuring the safe operation of this equipment. This needs to be carried out under HTM 06-03 safe system of work, also the need to understand how the high voltage system functions and interacts with the low voltage switchgear.  Grading of protection is an element that most HVAP’s find daunting to comprehend, this is, however, a fundamental part of the 10 day HVAP training delivered by Eastwood Park.

To carry this out it requires the on site HVAP to be site familiar with the safe operation and isolation of this equipment and have essential site and technical knowledge to provide the necessary supervision of these works.

With the above in mind, as the NHS has an extremely diverse staff base, from basically qualified electrical engineers to electrical Estates Officers with a very high level of technical ability, the challenge is to adequately manage these ever more complex high voltage systems. The NHS needs to focus on ensuring all hospital sites which have their own high voltage networks have suitably trained, site familiar and competent engineers who are able to operate the safe system of work required under HTM 06-03 and provide compliance with the Electricity at Work Regulations 1984. 

Arc flash

When it comes to maintaining and operating these systems one of the main issues which keeps arising with regard to electrical safety during AP training courses is the possibility of arc flash accidents and the wearing of suitable PPE.   Historically, statistics report that accidents that involve arc flashes invariably occur during or after work has been carried out, or during testing procedures.

There is also a popular misconception that this is predominantly a high voltage issue, however, low voltage systems cause more issues due to the fact that high voltage systems are usually worked on by highly trained engineers aware of the potential dangers and working to a set of safe working rules and procedures whereas low voltage systems are worked on much more regularly and by less well trained or even untrained electricians.

Due to the nature of the low voltage systems and the sheer amount of low voltage switchgear with respect to the amount of high voltage equipment the propensity for an incident is exponentially higher.

This can be negated by careful maintenance, reducing fault levels, correct protection settings, etc., part of the training for HVAP’s is to become familiar with how switchgear works, how to maintain it and operate it in a safe manner.

Before operating switchgear, the AP whether HV or LV must carry out a risk assessment. Training tells him what to look for, for example: how many times has it operated under fault; when was it last maintained; is it prone to partial discharge; if it is oil filled when was the dielectric strength last tested and are the protection settings correct.

Once this has been ascertained he can then make an informed decision on how to operate the switchgear, perhaps by remote operation.  If situations permit dead operation, this second choice can be almost impossible in a busy hospital, however the HTM’s prescribe to minimise single points of failure, this could mean there may be alternative LV supplies / UPS systems or generation, which will allow the dead and safe operation of the switchgear.

Due to the massive amounts of fault energy involved with a typical high voltage system, PPE may be the last resort option when all other options have been exhausted and the operator is still at risk of exposure to arc flash.

Again suitable training gives the HVAP the knowledge on how to correctly select appropriate PPE once he has either ascertained or calculated the arc thermal protective value required or the PPE.

As can be seen from the above, adequate training of the engineers both working on, testing and managing these systems needs to be a priority on NHS estates, not only for personal safety and compliance with both the Health and Safety at Work Act 1974 and the Electricity at Work Regulations 1989, but to also limit the propensity of catastrophic failure of the equipment and subsequent damage to property and patients.

If all Engineers, Estates Directors, Designated Persons and senior members of the clinical staff are made aware of the requirements and safe working practices laid out in both HTM 06-02 and HTM 06-03 it will make the operation and maintenance of the hospital electrical systems much safer and just as importantly compliance will be met and the standards maintained across the estate.