Common Power System Architectures for Health Care Facilities

in the previous Topic; Electrical Distribution systems for nursing homes and residential custodial care facilities , we talk about the electrical design methods for such buildings.

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
• the Electrical Distribution Systems for Hospitals - Part One
• the Electrical Distribution Systems for Hospitals - Part Two

Today, i will explain the Common Power System Architectures for Health Care Facilities as follows. 


Common Power System Architectures for Health Care Facilities:

the health care facilities have (4) common Power System Architectures as follows:

1. Radial – Generator.
2. Dual Source and Radial Secondary – Generators.
3. Secondary Selective – Generators.
4. Dual Source and Secondary Selective – Generators.

1- Radial – Generator


This is the simplest system to operate and has the lowest first cost. It is also very easy for maintenance people to understand. System can have outages for faults and maintenance. If utility source A is lost, the entire system is lost for 10 seconds until generators can be brought on-line. This system is normally used on smaller healthcare facilities.

Radial – Generator Power System Architecture

For smaller healthcare facilities, small nursing homes and residential custodial care facilities, a single service-entrance switchboard, and a small generator can be the major components of the electrical system. These facilities usually have several normal power panelboards fed from the normal power system. If motor loads are to be energized by the generator, their restoration under emergency conditions can be delayed by using a time-delay relay in the automatic transfer switch or by adding a time-delay relay in the motor starter, which is energized by auxiliary contacts within the transfer switch.

Where there will be significant emergency power requirements, several transfer switches may be used to increase reliability. The transfer switches used for the equipment system can be adjusted to transfer sequentially, thus minimizing generator inrush requirements.


Advantages:

• Low first cost. 
• Simple operation and understanding by personnel. 
• Easily expanded. 
• Radial ground fault. 

Disadvantages:

• Low Reliability. 
• Maintenance causes outages. 

2- Dual Source and Radial Secondary – Generators

A double-ended substation should be considered where transformation will exceed 750 kVA.

System has the ability to switch between two utility sources via auto throw-over scheme. Electrically operated medium voltage breakers are required for this transfer system. If both utility sources are lost, generators back up essential electrical loads via transfer switches. System design is reliable and used for medium to large size hospitals.

Dual Source and Radial Secondary – Generators  Power System Architecture

As health care facilities become larger, additional feeders for normal power loads and essential electrical power systems will be required. The essential electrical system will thus require three or more transfer switches, some of which could be non-automatic. Using several smaller transfer switches, in lieu of a large switch, will contribute to system stability and reliability.


Further, reliability can be obtained by placing the transfer switches as close to the ultimate load as possible.

For example, fig (1) shows two schemes for distributing power through vertical risers.

Fig (1)

When an outage occurs in the normal power supply, the transfer switches will direct an alternate power supply to the essential electrical system panelboards. However, if a specific normal feeder outage occurs, only Scheme A can sense the specific outage and restore power to the affected panel via the alternate power supply. Scheme A is more reliable than Scheme B, but is a more costly arrangement. Loss of normal power is sensed at the transfer device to initiate start-up of the emergency generator via auxiliary contacts. When the voltage and frequency of the emergency power is in proper limits, and stable, then relays initiate switching to the alternate power source. Finally, restoration of normal power causes the automatic transfer switches to return to the normal power source while initiating a shut-down of the emergency generator.

Advantages:

• Protection against loss of primary source. 
• Possible paralleling of sources. 
• Choice between Sources A or B. 
• Reliable. 

Disadvantages:

• Additional cost of equipment. 

3- Secondary Selective – Generators 

The secondary selective system allows the transfer of load from one transformer to the other with the use of electrically operated main and tie-breakers via auto throw-over scheme. This is important if one transformer fails or needs maintenance. If both utility sources are lost, generators backup essential electrical loads via transfer switches. Transformer sizing is critical if all secondary loads are to be serviced from one transformer. This is usually accomplished by either loading the transformers to 50%, or by using the transformer forced air (fan) rating with temperature controllers.

Secondary Selective – Generators  Power System Architecture

This system may require complex ground fault solution if both 480 Y/277 V transformers have separate grounds or if 3 pole transfer switches are used for 4 wire loads. This causes circulating current on the neutral busses.

This system is common in large cities where the utility companies use transformers, located in vaults, to service hospitals.

Advantages:

• Normal operation as radial system with stand-by generators. 
• Isolation of cable or transformer for faults or normal maintenance. 
• Feed other side with use of transfer scheme and electrically operated breakers. 
• Main and tie breakers can be interchanged for maintenance to keep outages to a minimum. 

Disadvantages:

• Additional cost. 
• Transformer load monitoring. 
• May require complex ground fault system if neutrals are tied together and sources have multiple grounding points. 

4- Dual Source and Secondary Selective – Generators

This system combines the advantages of both primary sources and secondary selective systems used with backup generators. It not only provides the more reliable system, but also one of the most costly system.

Dual Source and Secondary Selective – Generators  Power System Architecture

 

Evaluation of the probability of total downtime costs will be necessary to justify the additional first cost. This system may require complex ground fault solution if both 480 Y/277 V transformers have separate ground points or if

3 pole transfer switches are used for 4 wire loads. This causes circulating current on the neutral busses. This power system is popular for large hospital complexes.

Advantages:

• High Reliability. 
• Combined advantages of both sources and generators. 

Disadvantages:

• Higher initial cost. 
• May require complex ground fault system if neutrals are tied together and sources have multiple grounding points. 

in the next Topic, I will explain the Major Types of Electrical Loads. so, please keep following.

Electrical Distribution Systems for Nursing Homes and Residential Custodial Care Facilities

in the previous Topic; the Electrical Distribution Systems for Hospitals - Part Two, we talk about the Equipment system/ branch and  Electrical Design types according to size of hospital.

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
• the Electrical Distribution Systems for Hospitals - Part One

Today, i will explain the Electrical Distribution Systems for another type of health care facilities which is "Nursing Homes and Residential Custodial Care Facilities" as follows. 


second building type: Electrical Distribution systems for nursing homes and residential custodial care facilities:

In nursing homes and residential custodial care facilities, usually the Essential Electrical System type will be Type 2-ESS.

The essential electrical system is subdivided into two systems as follows:

1. The emergency system. 
2. The critical system. 

1- The emergency system:

Emergency system In these cases is limited to those loads defined for the life safety branch for hospitals, plus sufficient illumination to exit ways in dining and recreation areas. These emergency system circuits are required to be installed separately and independently of non-emergency circuits and equipment. The NFPA standards require that this emergency system branch be designed to permit automatic restoration of electrical power within 10 s of power interruption.

The emergency system shall supply power for lighting, receptacles, and equipment as follows:

• Illumination of means of egress.
• Exit signs and exit directional signs.
• Alarm and alerting systems, including the following: 

1. Fire alarms.
2. Alarms required for systems used for the piping of nonflammable medical gases.

• Communication systems, where used for issuing instructions during emergency conditions 
• Sufficient lighting in dining and recreation areas to provide illumination to exit ways of a minimum of 5 ft-candles 
• Task illumination and selected receptacles at the generator set location 
• Elevator cab lighting, control, communication, and signal systems 

Note: No function other than those listed above shall be connected to the emergency system


2- The critical system:

The critical system shall be so installed and connected to the alternate power source that equipment listed in below shall be automatically restored to operation at appropriate time-lag intervals following the restoration of the emergency system to operation. Its arrangement shall also provide for the additional connection of equipment listed as follows:

a- AC Equipment for Nondelayed Automatic Connection:
Generator accessories, including but not limited to, the transfer fuel pump, electrically operated louvers, and other generator accessories essential for generator operation, shall be arranged for automatic connection to the alternative power source.



b- Delayed-Automatic Connections to Critical System:
The following equipment shall be permitted to be connected to the critical system and be arranged for delayed-automatic connection to the alternate power source:

• Task illumination and selected receptacles in the following: 

1. Patient care areas.
2. Medication preparation areas.
3. Pharmacy dispensing areas.
4. Nurses’ stations (unless adequately lighted by corridor luminaires).

• Supply, return, and exhaust ventilating systems for airborne infectious isolation rooms.
• Sump pumps and other equipment required to operate for the safety of major apparatus and associated control systems and alarms.
• Smoke control and stair pressurization systems.
• Kitchen hood supply and/or exhaust systems, if required to operate during a fire in or under the hood.

c- Delayed-Automatic or Manual Connections to Critical System.
The equipment in below shall be permitted to be connected to the critical system and be arranged for either delayed-automatic or manual connection to the alternate power source as follows:



1- Heating Equipment to Provide Heating for General Patient Rooms.

Heating of general patient rooms during disruption of the normal source shall not be required under any of the following conditions: 

• The outside design temperature is higher than −6.7°C (+20°F). 
• The outside design temperature is lower than −6.7°C (+20°F) and, where a selected room(s) is provided for the needs of all confined patients, then only such room(s) need be heated. 
• The facility is served by a dual source of normal power.

2- Elevator Service.
In instances where interruptions of power would result in elevators stopping between floors, throw-over facilities shall be provided to allow the temporary operation of any elevator for the release of passengers.

In addition, connect the following items to the Critical Branch, arranged for delayed-automatic connection to the alternate power system:

• Nurse Call System.
• Patient Bedrooms: Bathroom light, an alcove or lavatory mirror light, night light, and one receptacle per bed wall.
• Electrical Rooms and Closets: 50 percent of lighting and one receptacle.
• Main Computer Room, Telephone Equipment Room and Telecommunications Rooms: UPS equipment, 50 percent of lighting, all receptacles and telecommunications equipment.
• Mechanical Rooms: Task illumination and one receptacle.

Electrical Design types according to size of Nursing House:

the electrical design will vary according the the size of the nursing house, you can know and extract the differences by yourself from reviewing the electrical single line diagrams in both cases ; small and large nursing house as follows:

1- Small  Nursing House case:

the electrical single line diagram will be as follows:

Electrical Single Line diagram for Small Nursing House

1- Large Nursing House case:

the electrical single line diagram will be as follows:

Electrical Single Line diagram for Large Nursing House

Alternate Source of Power for nursing homes and residential custodial care facilities: 

The alternate source of power shall consist of a diesel engine-driven generator set.



third building type: Electrical Distribution systems for other health care facilities:

Note: 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.

In other health care facilities, usually the Essential Electrical System type will be Type 3-ESS.

In other health care facilities, the Essential electrical system consists of one system supplying a limited amount of lighting and power considered essential for life safety and orderly cessation of procedure whenever normal electrical service is interrupted for any reason. The type of system selected should be appropriate for the medical procedures performed in the facility.

The Essential Electrical System for other health care facilities shall comply with the Type 3 system as defined in NFPA 99 as follows:

• The emergency system shall have an alternate source of power separate and independent from the normal source that will be effective for a minimum of 1.5 hours after loss of the normal source. 
• The emergency system shall be so arranged that, in the event of failure of normal power source, the alternate source of power shall be automatically connected to the load within 10 seconds. 

Note: If electrical life support equipment is required or critical care areas are present in the facility, the Essential Electrical System shall comply with the Type 1 system as defined in NFPA 99. If a Type 1 system is required, connect the functions/items listed in the topics for hospital design to the Essential Electrical System.


Alternate Source of Power for other health care facilities:

The alternate source of power for the system shall be specifically designed for this purpose and shall be a generator, battery system, or self-contained battery integral with the equipment.

in the next Topic, I will explain the Common power system architecture for Health care facilities. so, please keep following.

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 Facilities and 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 this previous topic 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 or under the 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 Director’s, 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. 

Electrical Design types according to size of hospital:

the electrical design will vary according the the size of the hospital, you can know and extract the differences by yourself from reviewing the electrical single line diagrams in both cases ; small and large hospital as follows:

11- Small hospital case:

the electrical single line diagram will be as follows:

Electrical Single Line diagram for Small hospital 

2- Large hospital case:

the electrical single line diagram will be as follows:

Electrical Single Line diagram for Small 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 with applying the 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).

in the next Topic, I will explain the Electrical Distribution systems for nursing homes and residential custodial care facilities. so, please keep following.

the Electrical Distribution Systems for Hospitals

In the previous topic, Electrical Design Requirements for Health Care Facilities – Part Two , We talk about 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).

You can review another previous topic; the Electrical Design Requirements for Health Care Facilities – Part One for 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.

in the next topic, i will continue explaining the Electrical Distribution Systems for Hospitals. so, please keep following.

Electrical Design Requirements for Health Care Facilities – Part Two

In the previous topic, the Electrical Design Requirements for Health Care Facilities – Part One , We talk about Health care facility definition, types, preliminary design consideration and electrical load types.

Today, we will talk about the power sources, Voltage considerations and electrical distribution system for health care facilities as follows.


Power sources in health care facilities:

Generally, the power sources that can be used in the electrical networks of health care facilities are as follows: (see fig.1)

1. The normal power source.
2. The alternate power source.

Fig (1)

1- The normal power source

The normal power source which may be one of the following:

1. The electric utility power.
2. On-site power generator(s) and in this case the alternate power source required can be another power generator unit or the electric utility. 

2- The Alternate Power Source

Alternate power source Definition:

1. One or more generator sets, or battery systems where permitted, intended to provide power during the interruption of the normal electrical services or the public utility electrical service intended to provide power during interruption of service normally provided by the generating facilities on the premises. 
2. Alternate power source by an on-site power source such as: 
3. Generator set(s) driven by some form of prime mover(s) and located on the premises. 
4. Another generating unit(s) where the normal source consists of a generating unit(s) located on the premises. 
5. An external utility service when the normal source consists of a generating unit(s) located on the premises. 
6. Uninterruptible power supply (UPS) (which can be applied as the principal alternate for large computing centers or other critical, sensitive loads). 
7.  battery/inverter system ( which can be applied as the principal alternate for nursing homes, residential custodial care facilities, and other health care facilities provided they meet the conditions outlined in NFPA 99-1996). 

Typically, the alternate sources of power are supplied to the loads through a series of automatic and/or manual transfer switches. The transfer switches can be non-delayed automatic, delayed automatic or manual transfer depending on the requirements of the specific branch of the EES (Essential Electrical System) that they are feeding.

It is permissible to feed multiple branches or systems of the EES from a single automatic transfer switch provided that the maximum demand on the EES does not exceed 150 kVA. This configuration called as (Radial – Generator) is typically seen in smaller health care facilities that must meet ESS Type 1 requirements.


Health care Facilities voltage classification:

Health care Facilities are primarily people- and public-oriented and because of their different sizes and types, they can need electrical supply with different voltage classes , for examples simple medical office /clinic will need an electrical supply with low voltage class (under 1000 V) from public Low Voltage grid while a large hospital will need an electrical supply with medium voltage class (UP to 20KV) Via public or in-house MV substations, for more information about different voltage classes , please review the following links:

Course EE-1 : Voltage Ranges -Part One 

EE-1 Course: Voltage Ranges - Part Two

For more information about Electrical System Configurations press on the link

Special voltage considerations for health care facilities:

• The proper selection, regulation, and quality of utilization voltages is extremely important because of the extensive use of sensitive medical equipment that is available in many different voltage ratings. 

• The voltage levels selected will depend on the utility voltage available, the size of the health care facility, the loads served, expansion requirements, the building layout, voltage regulation requirements, and cost. 

• Typically, a large health care facility will be supplied power at a medium voltage level from the utility and it will be stepped-down to either 480Y/277 V or 208Y/120 V for utilization. 

• Either 480 V or 208 V can be used to supply mechanical equipment (chillers, fans, pumps, etc.), medical equipment (radiology, medical air pumps, etc.), and other support equipment such as laboratory equipment and kitchen equipment. 

•  If 480 V is present, however, it is preferred. From initial cost considerations, ongoing operating cost reasons, and isolation from sensitive 120 loads, the 480 V level is the better choice for these equipment. 

• The use of 277 V lighting in lieu of 120 V in large health care facilities is common. The application of 277 V lighting in hospitals, however, differs from other commercial facilities because of the requirement for the four divisions of the electrical system (normal, critical branch, life safety branch, and the equipment system). Depending on other equipment requirements, applying 277 V lighting may increase the number of 480Y/277V panels on each floor and/or in each electrical room. 

• There is no general rule on when to apply 277 V lighting. Each individual application should be analyzed to determine its feasibility. Typical benefits of 277 V lighting include reduced system losses, reduced number of branch circuits for lighting, reduced sizes of power conductors, reduced heat gains on the air conditioning system due to power losses, and segregation of the harmonics of the electronic ballasts in luminaires from the medical equipment operating at 208Y/120 V. 

• Once the nominal utilization voltages have been selected, the voltage of all medical equipment to be installed in the facility should be carefully checked to assure proper application. 

• If the equipment is new, it should be ordered to one of the planned utilization voltages. If this is not possible, then buck/boost autotransformer, or standard two-winding transformers should be considered to supply rated voltage to the equipment. 

• A common misapplication includes the use of nominally rated 230 V motors installed on a 208 V system. 

Electrical Distribution systems in health care facilities:

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).

1- Electrical Distribution Systems for Hospitals

Electrical Distribution Systems for Hospitals is basically divided into two sub-systems as follows:

1. The normal electrical system (non-essential). 
2. The essential electrical system. 

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.


in the next Topic, I will continue explaining the  Electrical Distribution Systems for Hospitals. so, please keep following.

General Electrical Requirements for Healthcare Facilities

In the previous topic, Electrical Design Philosophy for Major Types of Buildings, 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:

• Electrical Design Requirements for Industrial Building
• Specific Electrical Design Requirements for Industrial Buildings – Part One
• Specific Electrical Design Requirements for Industrial Buildings – 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 the commercial buildings – Part Three
• Power system architectures for the commercial buildings – Part Four
• 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- Maintainability
The 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- Efficiency
The 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- Economy
Evaluate 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 loads
Lighting loads may be divided into the following broad categories

• Internal lighting loads.
• Special lighting loads.
• Outdoor lighting loads.

2- Power loads
Power 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 explaining the general electrical requirements for Healthcare facilities. So, please keep following.