ELECTRICAL SYSTEMS
such as switchgear, transformers, and cabling. It is often misunderstood that repair of such equipment can be the responsibility of the healthcare institution. Most DNOs will be able to issue a Site Responsibility Schedule (SRS) which clarifies ownership of all electrical equipment. The AE should provide guidance on all the requirements of the OPM.
Safety documentation for robust Safe Systems of Work
All too often we come across electrical work in progress where Safe Systems of Work are non-existent, or the incorrect safety documentation is in place at the point of work. Under current Construction and Organisation Safety rules, no work can take place without appropriate Risk Assessment and Method Statements (RAMS). However, RAMS play only a small part in a safe system of electrical work (SSoW). These RAMS should only form the basis of permitting contractors onto site to undertake electrical work, which should then be controlled by the Site Safe System of Work. The NHS suite of safety documents is second to none, in that it has been developed over years by working engineers in the healthcare environment. One area for concern is the service/maintenance and operational management of UPS systems: n Limitation of access (Entry to electrical room).
n Permission to disconnect (Approval from stakeholder).
n Isolation & Earthing Diagram (Status of system made dead and accompanying Permit to Work).
n Safety Programme (work required to enable issue of PTW).
n Permit to Work (working on systems made dead).
n Sanction for test (HV systems only). n Certificate of Authorisation for Live Working (UPS systems specifically).
n Live functional Testing LFT.1 form (UPS and live panel testing).
n Transfer of control (Hospital Construction Site).
Without the correct precautions, a potential problem such as an oil leak or tripping battery failure may remain undetected for an extended period.
n Request for Isolation and Earthing Certificate (Interface with DNO).
Complex HV systems and LV infrastructure systems The main concerns for the Authorising Engineer revolve mainly around complex HV systems and LV infrastructure systems, including tertiary support systems such as Uninterruptible Power Supply systems
AE Concerns (HV systems) In our current Authorising Engineer role for multiple healthcare organisations, many of which are supplied at high voltage, we are concerned by the increasing dependence on third- party contractors. While there are numerous competent HV maintenance contractors around, they will generally offer either an annual, or even four-yearly, contracts. The temptation for the healthcare organisation is to assume that HV equipment does not require any interim inspections between scheduled maintenance visits – remembering that the completion of these maintenance tasks is only part of the requirement, and should be considered along with the additional requirement for non-intrusive testing such as thermal imaging and
partial discharge. Therefore, without these precautions, a potential problem such as an oil leak or tripping battery failure may remain undetected for an extended period. In extreme cases this can lead to catastrophic failure, as shown left and in the photo on page 40.
It is thus essential that any organisation that owns HV and LV equipment has at least one appointed HV Authorised Person to carry out regular (monthly or at least quarterly) visual inspections of all such equipment. It should also be noted that anyone who is required to enter an HV substation or transformer enclosure to carry out non-electrical work (e.g. emergency lighting testing, fire alarm testing, or cutting back of foliage) should be in possession of a Limitation of Access issued by an HV AP.
Additional duties of an AE The AE role can be expanded to include additional duties, some of which can include: n Five-yearly risk-based condition reporting.
n Undertaking peer design reviews. n Attending interviews for key Estates positions.
n Liaising with District Network Operators (DNO).
n Countersignature of safety documentation in absence of APs.
n Checking the integrity and resilience of site DNO supplies.
Capacity and integrity of DNO supplies
The electrical AE audits carried out also assess the electrical capacity and resilience of the local DNO network. HTM 06-01 states that ‘Where two 11 kV supplies are provided, it is more beneficial for them to be from different networks’. This is often interpreted by designers as a requirement for supplies from two different primary DNO substations. This can be prohibitively expensive, and can severely restrict the flexibility of operating the site, as the DNO is unlikely to allow its two supplies to be paralleled via the site’s
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