This article from the experts at NICEIC looks at electrical installations in medical sites and will consider the scope of Section 710 of BS 7671 including some design requirements. The use of system assembly and how to apply the Section 560 safety service supply classification to these medical sites will also be considered.
The goal of Section 710 is to provide enhanced reliability of electrical installations, and increase electrical safety within the medical environment for both patients and medical staff.
The risk to the patient is greatly increased in the clinical setting due to:
• Threat of failure to supply medical equipment, especially those used for life support. and
• The natural decrease in the body’s resistance inherent in open wounds and interventional procedures and the subsequent decrease in the patient’s defensive ability either due to inducing drugs or during anaesthesia.
As with all special sites in Part 7, the requirements of Section 710 supplement or modify the general requirements of BS 7671 and are intended for those parts of electrical installations on sites providing patient care, diagnosis, treatment and monitoring. The requirements do not apply to items of medical electrical equipment.
The scope of Section 710 sets forth special requirements applicable to patient health care centers and facilities including:
• Hospitals.
• Private clinics.
• Medical and dental practices.
• Dedicated medical rooms in the workplace. and
• Patient-specific medical research institutions.
The requirements may also apply to veterinary clinics, where applicable.
Healthcare-related building contracts must also meet the requirements specified in the Supporting Information for Healthcare Buildings set out in Health Technical Note (HTM) 06-01 Supply and Distribution of Electrical Services, and 06-02 Electrical Safety Guidelines for Low Voltage Systems, published by the Department of Health.
Equivalent guidance documents are available for the devolved administrations: Scotland (SHTM), Wales (WHTM) and Northern Ireland (HTM) (Note 6 refers to Regulation 710.1).
Although there are often slight differences in approach between BS 7671 and the specific HTM, the designer must always adhere to the requirements of BS 7671. Where a standard does not provide sufficient information on a particular issue or detail, guidance should be provided in the relevant HTM and should then be applied. . However, this guidance should not conflict with the requirements of BS 7671.
Evaluation of general characteristics
Part 3 of BS 7671 sets out the characteristics that should be assessed for all electrical installations.
The designer responsible for electrical installations, within a medical site, must determine both the appropriate group in which a particular medical site is located, and the classification that will be applied to electrical safety services at those sites.
Medical website classification is usually based on:
• The type of physical contact between the patient and the applicable parts¹ of medical equipment (ME) or ME systems;
• Threat to patient safety if supplies are interrupted. and
• The purpose for which the site will be used.
To determine the appropriate level of classification that should be applied, based on the intended medical procedures likely to occur within the site, it is necessary for the electrical installation designer to communicate with medical/clinical professionals (710.3).
To ensure safety on a medical site, where the site will be used for multiple procedures or medical treatments, requirements applicable to more difficult use should apply.
Assembly
The guidance in Table 1 highlights the definitions of Groups 0, 1 and 2 locations specified in Part 2 of BS 7671 and provides, based on Appendix A710 of Section 710, some examples of rooms that are likely to be included in each group.
It remains the responsibility of the designer, in consultation with the relevant clinical staff, to determine the appropriate combination for a particular site. It should also be kept in mind that the list is not final.
Safety service rating
As described previously, electrical failure at a medical site can be life-threatening. Therefore, appropriate safety services are necessary to prevent such risks, and may usually include providing a backup source of operating room lighting.
Regulation 560.4.1 provides classification of supplies for safety services. Section 710 requires that these types of automatic supplies of safety services be ready to operate within the maximum changeover time assigned to a particular area.
Table A710 of the Section 710 Appendix provides guidance on maximum changeover times allowed at typical clinical sites.
For example, within bedrooms and massage rooms, a changeover period of no more than 0.5 seconds and no more than 15 seconds is recommended while a time of no more than 0.5 seconds is recommended for luminaire supplies and life support equipment in locations such as operating theatres.
More design considerations
There may also be a need to take into account the requirements of other sections in Part 7 of BS 7671, particularly where it is necessary to modify electrical installations due to a change in use of the site. For example, when such intended work includes areas containing a bathroom or shower (701), or mobile medical units or transportable units (717).
Care must be taken to ensure that any such installation, or necessary work, does not affect or compromise the level of safety imposed by Section 710, including effects resulting from:
• Fault current.
• Electromagnetic interference (EMI).
• Electromagnetic compatibility EMC. or
• fire.
Although BS 7671 should not be applied retrospectively, when considering electrical work on an existing medical site, every intended change or addition must be preceded by a full risk analysis to ensure that the work intended is suitable and will not compromise safety.
summary
This article has set out some of the considerations within the scope of section 710 of BS 7671 for different types of medical facilities. Requirements for specific groups and classifications of supply of safety services used in the medical/health care environment are also taken into account.
We would like to acknowledge and thank Brandon Medical for providing the image used in this article.
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