The Electrical Distribution Systems for Hospitals
The Electrical Distribution Systems for Hospitals
http://www.electrical-knowhow.com/2012/02/general-electrical-requirements-for.html
In the previous topic,ElectricalDesign Philosophy for Major Types ofBuildings,We talk about the different types of buildings and how the building type (function) influences its electrical design.
This was very clear in our previous discussions for the electrical design requirements of both industrial and commercial buildings which were included in the following topics:
1- Industrial buildings: ElectricalDesignRequirementsfor Industrial Building SpecificElectricalDesignRequirementsfor IndustrialBuildings Part One SpecificElectricalDesignRequirementsfor IndustrialBuildings Part Two
2- Commercial buildings: General Electrical Design Requirements for Commercial Buildings Specific Electrical Design Requirements for Commercial Buildings Power system architectures for the commercial buildings Part One Power system architectures for the commercial buildings Part Two Power system architectures for thecommercialbuildingsPartThree Power system architectures for thecommercialbuildingsPartFour Power System Architectures for the Commercial Buildings Part Five Comparison between Power system architectures for the commercial buildings
Today, I will explain the third type of buildings which is Healthcare buildings although these type of buildings generally categorized under the commercial buildings but as they were important type of buildings, we will assign special topics for clarifying the electrical requirements of this type of buildings.
Health care facility definition:
Health or personal care facility refers to buildings or parts of buildings that contain, but are not limited to, hospitals, nursing homes, limited care facilities, clinics, medical and dental offices, and ambulatory care centers, whether permanent of movable and such other health care occupancies where patients who may be unable to provide for their own needs and safety without the assistance of another person are treated.
Health care facility famous types:
1- Hospital (General Medical and Surgical)
Hospitals are Buildings used as diagnostic and treatment facilities for inpatient care. it applies to a general medical and surgical hospital that is either a stand-alone building or a campus of buildings.
These facilities provide acute care services including emergency medical care, physician's office services, diagnostic care, ambulatory care, surgical care, and limited specialty services such as rehabilitation and cancer care.
The definition of Hospital accounts for all space types that are located within the Hospital building/campus, such as medical offices, administrative offices, and skilled nursing. The total floor area should include the aggregate floor area of all buildings on the campus as well as all supporting functions such as: stairways, connecting corridors between buildings, medical offices, exam rooms, laboratories, lobbies, atria, cafeterias, storage areas, elevator shafts, and any space affiliated with emergency medical care, or diagnostic care.
2- Medical Office/ clinic
Medical Office applies to facility space used to provide diagnosis and treatment for medical, dental, or psychiatric outpatient care where patients are not regularly kept as bed patients for twenty-four hours or more. The total gross floor area should include all supporting functions such as kitchens used by staff, laboratories, lobbies, atria, conference rooms and auditoria, fitness areas for staff, storage areas, stairways, elevator shafts, etc.
3- "Nursing home," "nursing home unit" or "long-term care unit"
It refers to buildings having a group of beds for the accommodation of patients who, because of chronic illness or physical infirmities, require skilled nursing care and related medical services but are not acutely ill and not in need of the highly technical or specialized services ordinarily a part of hospital care.
4- "Ambulatory surgical facility or Ambulatory Health Care Center
It refers to a facility, not a part of a hospital, providing surgical treatment to patients not requiring inpatient care in a hospital.
Preliminary design phase (planning) for health care facilities
During this phase, preliminary design data is gathered from administrators and staff of the health care facility, the local utility, and authorities having jurisdiction over electrical construction. All relevant national, state, and local codes, and facility design guidelines, should be reviewed.
Two national codes having a major affect on health care power distribution design are The National Electrical Code (NEC) (NFPA 70-1996).
NFPA 99-1996, Health Care Facilities.
In addition, the architectural plans and existing site conditions should be examined from an electrical system perspective to determine potential problems and needs. The following issues should be addressed during the system planning phase of the design:
1- Reliability:Alternative power systems may be authorized, but are limited to serving certain essential loads for critical, hospital, and other special facilities and loads as identified therein. The designer shall consider the location and space for essential electrical system components in order to limit interruptions caused by localized natural conditions, such as floods and earthquakes. Essential systems will be designed to function after seismic events occur. Non-essential systems may be inoperable, but components will be constrained to avoid personnel injury, or damage to other building components.
2- Durability:Installed electrical systems and electrical equipment will have a minimum rating for continuous full design load, except where other criteria mandate greater, to meet the reliability requirements for the design life of the facility.
3- MaintainabilityThe design and construction for facilities will provide a means to remove and maintain equipment, and field installed wiring without interruption to mission critical loads.
4- EfficiencyThe efficiency of the facility electrical system, measured at the utilization transformer secondary and the alternative power source, will have a power factor (PF) not less than 0.90 at nominal voltage for balanced three phase loading (phase unbalance will not exceed 5 percent between A, B, and C phase). Where required power factor correction shall be used to assure a minimum PF of 0.90.
5- EconomyEvaluate alternative system configurations, and component types and sizing for economic value, consistent with other criteria factors above.
Once the system planning phase is complete, the designer will have the necessary information to begin the actual design of the electrical distribution system for the health care facility.
Load requirements for healthcare facilities
The major loads to be served by the electrical system in health care facilities will be divided into two types; lighting and power loads as follows:
1- Lighting loadsLighting loads may be divided into the following broad categories Internal lighting loads. Special lighting loads. Outdoor lighting loads.
2- Power loadsPower loads may be divided into the following broad categories:
1- Building equipment: Heating, ventilating, air conditioning and refrigeration (HVAC&R).
Transportation (elevators, escalators, trolleys).
Auxiliary pumps (fire, sump, clinical air and vacuum, pneumatic tube).
2- Functional equipment: Kitchen.
Data processing.
Communication systems.
Business machines.
Laundry.
3- Medical equipment: X-ray and imaging systems
Radiation therapy.
Laboratory.
Surgery.
Intensive care, recovery, emergency.
Physical and occupational therapy.
Inhalation therapy.
Pharmacy.
Materials management.
Medical records.
NOTE: Major loads occur in the first two categories (building & functional equipment) and these loads are similar to those in other types of commercial buildings. The third category (medical equipment) is unique to health care.
In the next Topic, I will continue explainingthe general electrical requirements for Healthcare facilities. So, please keep following.Power sources in health care facilities, Health care Facilities voltage classification and mentioned that we will study the Electrical Distribution systems for the following health care facilities:
1. Hospitals.2. Nursing homes and residential custodial care facilities.3. Other health care facilities (excluding hospitals, nursing homes, and residential custodial care facilities where the facility administers inhalation anesthetics or requires electromechanical life support devices).
the Electrical Design Requirements for Health Care Facilities Part Onefor more information and good following.
Today, we will begin studying the Electrical Distribution systems for Hospitals as follows.
General Electrical Distribution Systems for Health Care Facilities
Electrical Distribution Systems for Health Care Facilities is basically divided into two sub-systems as follows: (see fig.1)1. The normal electrical system (non-essential).
2. The essential electrical system.
Fig (1):Electrical Distribution Systems for Health Care Facilities
Note: Both systems are supplied by the normal power source; however, the essential electrical system can be transferred to the alternate power supply whenever the normal power source experiences a power failure.
1- Non-essential electrical system:
The non-essential electrical system consists of distribution equipment and circuits that supply electrical power from the normal power supply to loads that are not deemed essential to life safety, or the effective, and essential operation of the health care facility.
These non-essential or normal loads include things such as general lighting, general lab equipment, non-critical service equipment, patient care areas, etc. These loads are not required to be backed up with an alternate source of power.
2- Essential electrical system:
The essential electrical system consists of the alternate power supply (or supplies), transfer equipment, distribution equipment, and the circuits required to assure continuity of electrical service to those loads deemed as essential to life safety, critical patient care, and the effective operation of the health care facility.
Essential electrical system include three different types as follows:
1. Essential Electrical System: Type 1-ESS.
2. Essential Electrical System: Type 2-ESS.
3. Essential Electrical System: Type 3-ESS
We will know the differences between these types along our next discussion for the electrical distribution systems for different health care facilities.
First: Electrical Distribution Systems for Hospitals
In hospitals, usually the Essential Electrical System type will be Type 1-ESS.
Important considerations in design of Essential electrical system Type 1: Dual sources of normal power shall be considered but shall not constitute an alternate source of power
Distribution system arrangements shall be designed to minimize interruptions to the electrical systems due to internal failures by the use of adequately rated equipment
The following factors shall be considered in the design of the distribution system:
Abnormal voltages such as single phasing of three-phase utilization equipment, switching and/or lightning surges, voltage reductions, and so forth
Capability of achieving the fastest possible restoration of any given circuit(s) after clearing a fault
Effects of future changes, such as increased loading and/or supply capacity
Stability and power capability of the prime mover during and after abnormal conditions
Sequence reconnection of loads to avoid large current inrushes that trip overcurrent devices or overload the generator(s)
Bypass arrangements to permit testing and maintenance of system components that could not otherwise be maintained without disruption of important hospital functions
Effects of any harmonic currents on neutral conductors and equipment
Current-sensing devices, phase and ground, shall be selected to minimize the extent of interruption to the electrical system due to abnormal current caused by overload and/or short circuits
Generator load-shed circuits designed for the purpose of load reduction or for load priority systems shall not shed life safety branch loads, critical branch loads serving critical care areas, medical air compressors, medical-surgical vacuum pumps, pressure maintenance (jockey) pump(s) for water-based fire protection systems, generator fuel pumps or other generator accessories
Essential electrical systems shall have a minimum of two independent sources of power: a normal source generally supplying the entire electrical system and one or more alternate sources for use when the normal source is interrupted
Where the normal source consists of generating units on the premises, the alternate source shall be either another generating set or an external utility service
Essential electrical system branches:
Essential electrical system will include the following two sub-system:1- Emergency system: which include the following two branches:(see fig.2) Life Safety Branch.
Critical Branch.
2- Equipment System/branch.
fig (2):Essential electrical system branches
1-a Life Safety Branch
A subsystem of the emergency system consisting of feeders and branch circuits meeting the requirements of article 700 intended to provide adequate power needs to ensure safety to patients and personal, and which are automatically connected to alternate power sources during interruption of the normal power source
Shall supply power to loads per NFPA 70 and 99, including the following:
Alarm and alerting systems, such as Fire Alarm and Medical Gas Systems.
Automatic doors: Used for building egress.
Elevator cab lighting, control, communication, and signal systems.
Exit signs.
Generator set location: Task illumination, battery charger for emergency battery-powered lighting units and selected receptacles.
Illumination of means of egress.
Telecommunications Systems where used for issuing instructions during emergency conditions, including public address and Code One (Blue) systems and Disaster Control or Emergency Communication Centers.
1-b Critical Branch:
A subsystem of the emergency system consisting of feeders and branch circuits supplying energy to task illumination, special power circuits, and selected receptacles serving areas and functions related to patient care, and which are connected to alternate power sources by one or more transfer switches during interruption of the normal power source. The critical branch of the emergency system shall supply power for task illumination, fixed equipment, selected receptacles, and special power circuits serving the following areas and functions related to patient care:
Acute Nursing: Task illumination and selected receptacles.
Step-down Units: Task illumination and selected receptacles.
Anesthetizing Locations: Task illumination, selected receptacles and fixed equipment; task illumination includes battery back-up.
Angiographic Laboratories: Task illumination, selected receptacles and selected power circuits.
Blood, Bone, Eye and Tissue Banks: Task illumination, selected receptacles and refrigerators.
Cardiac Catheterization Laboratories and Rooms: Task illumination and X-ray unit.
Coronary Care Unit: Task illumination and PBPUs.
Emergency Room Treatment Areas and Life Support Rooms: Task illumination and PBPUs.
General Patient Bedrooms: Night lights, an alcove or a lavatory mirror light, one receptacle per bed wall, preferably in the PBPU, if available and a bathroom light.
Hemodialysis Rooms: Task illumination and one receptacle for each dialysis unit PBPU
Human Physiology Labs: Task illumination, selected receptacles and selected circuits.
Intensive Care Units: Task illumination and PBPUs.
Medication Rooms and Medication Preparation Areas: Task illumination, selected receptacles and refrigerators.
Minor Operating Rooms: Task illumination and selected receptacles.
Nurse Call systems.
Nurses Stations: Task illumination and selected receptacles.
Pharmacy Dispensing Area (including Satellite Pharmacies): Power files, laminar flow hoods, refrigerators, copier for transmittal of physicians' orders, task illumination and selected receptacles.
Psychiatric Bedrooms: Task illumination (ceiling only).
Surgical Operating Rooms: Task illumination (50 percent of the general fluorescent fixtures above the surgery table including battery backup within two of these fixtures), each X-ray unit and one film processor per suite.
Surgical Recovery Rooms: Lighting fixture over each bed, one receptacle for each bed (or PBPU), night lights for each bed (or PBPU) and emergency alarm circuits.
Main Computer Room, Telephone Equipment Room, Telephone Console Room, Head End Room, and Telecommunications Rooms: All UPS equipment, lighting, and receptacles.
Ward Treatment Rooms: Task illumination and selected receptacles.
The Electrical Distribution Systems for Hospitals - Part Two
in the previous Topic;the Electrical Distribution Systems for Hospitals - Part One,we talk about types of Electrical Distribution Systems for Health Care Facilitiesand we mentioned that the Essential electrical system will include the following two sub-system:
1- Emergency system: which include the following two branches:(see fig.1) Life Safety Branch.
Critical Branch.
2- Equipment System/branch.
I explained in thisprevioustopic the Life Safety Branch and Critical Branch.
You can review the following previous topics for more information and good following: the Electrical Design Requirements for Health Care Facilities Part One the Electrical Design Requirements for Health Care Facilities Part Two
Today, i will explain the second branch of Essential electrical system which is Equipment System/branch as follows.
fig.1
2- Equipment System/Branch:
Definition:A subsystem of the essential electrical system consisting of The feeder conductors and equipment used to supply electrical power to the equipment branch of the essential electrical system.
the Equipment that fed from Equipment System/Branch will be divided into three ttypes as follows:
1. Equipment Branch Non-Delayed Automatic Connection.
2. Equipment Branch Delayed-Automatic Connection.
3. Equipment for Delayed Automatic or Manual Connection.
1- Equipment Branch Non-Delayed Automatic Connection
it include the following generator accessories which must be arranged for non-delayed automatic connection to the alternate power source: Electrically operated louvers
Other generator accessories essential for generator operation
Transfer fuel pump
Equipment Branch Delayed-Automatic Connection
2- Equipment Branch Delayed-Automatic Connection:This equipment shall be arranged for delayed automatic connection to alternate power source. This means an outage to this equipment can exceed 10 seconds. Vacuum pumps and oral evacuation pumps serving medical and surgical functions, including controls.
Sump pumps and other equipment required to operate for the safety of major apparatus, including associated control systems and alarms.
Medical and dental air compressors, serving medical and surgical functions, including controls (such systems may be connected to the Critical Branch; the A/E shall coordinate with the Chief Engineer at the facility).
Smoke control and stair pressurization.
Kitchen hood supply and/or exhaust systems, if required to operate during a fire in orunderthe kitchen hood.
Uninterruptible Power Supply (UPS) equipment serving other than telecommunications equipment.
Medical and laboratory refrigerators and freezers as required.
Oxygen storage control panel.
Fire pump, jockey pump, and make-up pump for water-based fire protection systems; lighting and selected receptacles in fire pump room.
Autoclaving equipment (shall be permitted to be arranged for either delayed-automatic or manual connection to the alternate source).
Administrative Areas: Task illumination and selected receptacles in the hospital Directors, Engineering, and Security and Communications Suites.
Closed-loop water chilling equipment for linear accelerator.
Domestic Water Pumps: Equipment, control system, light fixture and receptacle near the pump.
Electric tape for heat tracing of piping requiring freeze protection.
Heating, ventilating and air-conditioning (HVAC) systems:
1. Air-conditioning equipment, lubricating oil pumps for centrifugal compressors, control air compressors, air dryer and absorption machine refrigerant pump to draw down lithium chloride before crystallization (omit for machines accomplishing this manually).
2. Chillers, chilled water circulating pumps, fans, and controls for surgical suites, recovery rooms, intensive care, and coronary care units.
3. Chillers, chilled water circulating pumps, fans and controls for animal research facilities.
4. HVAC equipment for Bone Marrow Transplant (BMT) areas.
5. HVAC equipment for Magnetic Resonance Imaging (MRI) Suites and Computerized Topographic (CT) Scanners.
6. HVAC equipment serving emergency areas in outpatient clinics in seismic and high-risk hurricane areas.
7. HVAC equipment for Main Computer Room and Telephone Equipment Room, Telephone Console Room, and Head End Room.
8. Exhaust fans serving Autopsy Rooms, reagent-grade Water Treatment Rooms, Orthotic Laboratory special exhaust systems, battery charging areas, flammable storage rooms and illustration rooms (Medical Media).
9. Supply, return and exhaust ventilating systems for Infection Isolation Rooms, Protective Environment Rooms and exhaust fans for laboratory fume hoods and nuclear medicine areas where radioactive material is used. These systems are permitted on delayed automatic system only and shall not be served via manual system. Some systems may be placed on Critical Branch. Coordinate with VA.
10. Ventilation, cooling and control equipment for electrical rooms.
11. Ventilation, cooling and control equipment for elevator machine rooms.
Hot Water Circulatory and Steam Condensate Return Pumps: Equipment, controls, and light fixture and receptacle near the pumps.
Hot Water Generator: Equipment, controls, and light fixture and receptacle near the generator.
Kitchen: Illumination and minimum equipment to feed patients during extended outage; freezers and refrigerators.
Laboratory Air Compressors and Vacuum Pumps: Equipment, controls, and light fixture and receptacle near the compressors and pumps.
Animal Ward lighting.
Mortuary Refrigerator or Cold Room: refrigeration equipment and task illumination
Radiology Suite: Task illumination, one automatic X-ray film processor, and one X-ray unit.
Refrigerated Medical Storage: refrigeration equipment.
Sewage Pumps: Equipment, controls, and light fixture and receptacle near the pumps
Supply, Processing, and Distribution (SPD):
1. Task illumination and selected receptacles in the following areas: core, sterile storage, non-sterile storage, preparation, and decontamination.
2. One ultrasonic cleaner, one ethylene oxide gas sterilizer, one steam sterilizer, one washer sterilizer, one gas generator.
3. Equipment in warehouse areas needed to preserve subsistence drugs and X-ray film materials that may be subjected to damage from infestation, humidity or temperature.
Water and Sewage Treatment Plant: Lighting, receptacles and equipment needed during emergency.
3- Equipment for Delayed Automatic or Manual Connection:
This equipment shall be arranged for either delayed automatic or manual connection to alternate power source. As mentioned for delayed automatic connection, an outage to this equipment can exceed 10 seconds. Heating equipment to provide heating for operating, delivery, labor, recovery, intensive care, coronary care, nurseries, infection/isolation rooms, emergency treatment spaces and general patient rooms.
An elevator(s) selected to provide service to patient, surgical, obstetrical and ground floors during interruption of normal power.
Supply, return and exhaust ventilating systems for surgical and obstetrical delivery suites, intensive care, coronary care, nurseries, infection/isolation rooms, emergency treatment spaces and exhaust fans for laboratory fume hoods, nuclear medicine areas where radioactive material is used, ethylene oxide evacuation and anesthesia evacuation.
Hyperbaric facilities.
Hypobaric facilities.
Automatically operated doors.
Minimal electrically heated autoclaving equipment shall be permitted to be arranged for either automatic or manual connection to the alternate source.
Selected controls.
ElectricalDesigntypes according to size of hospital:the electrical design will vary according the the size of the hospital, you can know and extract thedifferencesby yourself from reviewing the electricalsingleline diagrams in both cases ; small and large hospital as follows:
11- Small hospital case:the electricalsingleline diagram will be as follows:
ElectricalSingleLine diagram forSmall hospital
2- Large hospital case:the electricalsingleline diagram will be as follows:
ElectricalSingleLine diagram forSmall hospital
Alternate Source of Power for Hospital Buildings ( Type 1 - ESS):
The alternate source of power shall be one or more diesel-engine-driven-generator sets withapplyingthe following points: you must Provide physical space for one additional generator; paralleling switchgear shall be appropriately provisioned. Generator remote alarm annunciator(s) must be used in Energy Center control room, and the Security office or Telephone Operator office (whichever is continuously staffed).
