Electrical Safety in Operating Rooms: Installation Requirements
1. Purpose and Scope
The purpose of this investigation is to determine the specific requirements for electrical equipment in operating rooms and intervention halls, and the conditions for installing the receivers in receiving them. The object of this is to meet the requirements of applicable European Directives under the provisions in Article 6 of the Regulation for Low Voltage Electro.
In addition to the local general requirements for sanitary purposes identified in the ITC-BT-28, the detailed requirements included in this statement will be followed.
2. General Safety and Installation
Anesthesia rooms and other facilities where anesthetics or other flammable products can be used shall be considered as local fire or explosion risk Class I, Zone 1, unless otherwise stated, and as such the facilities must meet established guidelines for them ITC-BT-29. The outlet bases for different voltages will have separations or different ways to the corresponding pin of the pins.
When the lighting installation is situated at a height of 2.5 meters below ground, or when their switches present accessible metal parts, they shall be protected against indirect contacts through a differential device, as stated in the ITC-BT-24. The insulation characteristics of drivers shall be as provided in the ITC-BT 19 and, if necessary, the ITC-BT-29.
2.1. Protection Measures
2.1.1. Grounding Protection
The wiring of buildings with local medical practice, and in particular for operating rooms or intervention rooms, must have a three-phase supply with neutral and protective conductor. Both the neutral and the protective conductor shall be copper conductors, insulated type, along all installation. The common impedance between the busbar grounding of each operating room or room for intervention and grounding connections or contacts ground bases outlet should not exceed 0.2 ohms.
2.1.2. Equipotential Connection
All accessible metal parts must be attached to the equipotential bonding (EE in Figure 1), using isolated and independent copper conductors. The impedance between these parts and the equipotential bonding (EE) shall not exceed 0.1 ohms. The green-yellow identification should be used for equipotentiality and protection drivers.
The equipotential bonding (EE) is connected to the grounding of protection (PT in Figure 1) by an insulated conductor with the green-yellow identification, and a section not less than 16 mm2 copper. The potential difference between accessible metal parts and equipotential bonding (EE) should not exceed 10 mV effective in normal conditions.
2.1.3. Supply Through an Isolation Transformer
It is required to use isolation transformers or circuit separation, at least one for each room or operating room, to increase reliability of power supply to those computers that a disruption may endanger, directly or indirectly, the patient or the personnel involved and limit the leakage currents that may occur (see Figure 1). There will be adequate overcurrent protection of the transformer itself and feeder circuits. Particular importance is attached to the coordination of overcurrent protection of all circuits and equipment fed through an isolation transformer in order to prevent a fault in one circuit from putting out of service all the systems fed through the aforementioned transformer. The isolation transformer and the watchdog of the isolation level must meet the UNE 20.615. A scorecard and protection intervention room or operating room, located outside, easily accessible and nearby, will be available. This shall include overcurrent protection, transformer isolation, and a level monitoring device isolation. It is very important in the control panel and display panel of the state of isolation, all controls are clearly marked and easily accessible. The alarm box device monitoring the level of insulation must be inside the operating room or room for intervention and be easily visible and accessible, with easy substitutability of its elements.
2.1.4. Non-Differential and Overcurrent Protector
Protective devices should be used high-sensitivity differential (£ 30 mA) and class A for the personal protection of those teams that are not fed through an isolation transformer, although their use does not obviate the need for earthing and equipotentiality.
The protections for overcurrent devices will be provided. Those fed through an isolation transformer should be protected with no differential in the primary or the secondary of the transformer.
2.1.5. Use of Very Low Safety Voltage
Facilities with Low Voltage Security (MBTS) have a rated voltage not exceeding 24 V AC and 50 V DC and will comply with the ITC-BT-36.
2.2. Additional Supplies
Apart from providing supplementary reserve requirements of the ITC-BT 28, it will be compulsory to have a supplementary special provision, e.g., batteries, to meet the needs of the operating room lamp or room for intervention and life support equipment and must enter service automatically in less than 0.5 seconds (short cut) and with a range of not less than 2 hours. The operating room lamp or room intervention will always be powered through an isolation transformer (see Figure 1). All protection systems should operate with the same reliability as if feeding is done by the normal supply as the complement.
2.3. Measures Against the Risk of Fire or Explosion
For operating and intervention rooms to be used in mixtures of flammable anesthetic gas or disinfecting agents, Figure 2 shows the areas G and F, which should be considered areas of Class I, Zone 1 and Class I, Zone 2, respectively, as stated in the ITC-BT-29. Area F, located beneath the operating table (see Figure 2) may be considered as a safe zone of fire or explosion where ventilation of 15 air changes/hour is ensured. The soils of operating or intervention rooms will be antielectrostatic type and its insulation resistance shall not exceed 1 MW, except to ensure that a higher value, but always less than 100 MW, is not conducive to electrostatic charge build-up. In general, a proper ventilation system is prescribed to prevent concentrations of the gases used for anesthesia and disinfection.
Figure 2. Areas with risk of fire and explosion in operating rooms, when using mixtures of flammable anesthetic gas or disinfecting agents
2.4. Control and Maintenance
2.4.1. Before the Commissioning of the Installation
The authorized installation company shall provide a written report on the results of the checks carried out in terms of the execution of the installation, comprising at least:
- Operation of protection measures
- Continuity of the active conductors and protection grounded
- The strength of connections, protection drivers, and equipotentiality connections
- Resistance between active conductors and earth in each circuit
- Resistance grounding
- Insulation resistance of antielectrostatic soil
- The operation of all additional supplies
2.4.2. After its Commissioning
The proper functioning of the insulation monitoring device and protection devices will be checked at least weekly. Likewise, there will be measures of continuity and insulation resistance of the various circuits inside the operating and intervention rooms, at least monthly. The maintenance of the various teams must follow the manufacturer’s instructions. The periodic review of facilities generally must be made as provided in the ITC-BT-05, including in any case, the checks listed in 2.4.1. In addition to periodic inspections in the ITC-BT 05, there will be an annual review by an approved installation company, including, in both cases, the verifications referred to in 2.4.1 above.
2.4.3. Book-keeping
All checks will be collected in a “book keeping” of each operating or intervention room, which expresses the results achieved and the dates that were made with the signature of the technician who conducted them. Similarly, the anomaly reported will be reflected in detail, to have a history that can serve as a basis for correcting deficiencies.
3. Special Installation of Receivers in Operating and Intervention Rooms
All metallic masses of invasive electrical receivers will be connected through a protection conductor to a common grounding protection (PT in Figure 1) and this, in turn, to the general grounding of the building. Invasive electrical receiver means that from the electrical standpoint, it partially or completely penetrates inside the body, either through a body orifice or through the body surface. That is, those products by endocavitary operation that could present a risk to the patient due to microshocks. As an example, you can cite, electrocautery, radiological equipment, cardiovascular intervention, monitoring equipment, etc. Non-invasive receivers must connect to the power supply network through an isolation transformer. The non-invasive electrical receivers, such as magnetic resonance, ultrasound, analytical equipment, non-interventional radiological equipment, follow the general rules for receiver installation identified in the ITC-BT-43.