Isolated Power Systems
Line Isolation Monitors

Isolated power systems are electrical systems that are used in operating rooms and other wet locations throughout many hospitals. This system provides for additional safety against hazardous ground fault hazard.

The isolated power system incorporates the use of monitors, called Line Isolation Monitors. These are informally called LIMs by technicians in the field. The line isolation monitor replaces the circuit breaker. It will alarm, instead of tripping a circuit breaker, during most ground-fault occurrences.

According to the National Fire Protection Association publication NFPA99, these systems and their accompanying line isolation monitors must be tested and re-certified once per year. BiomedRx provides these annual inspections and the documentation to satisfy NFPA99 and Joint Commission for the Accreditation of Healthcare Organization requirements.

As BiomedRx adheres to the highest standard of service accountability and reporting, every client is provided with a secure online report portal. This living service report contains video, image, and text documentation of all service events.

Please read the information extracted from NFPA99 below.

Contact us to schedule an inspection of your isolated power systems and line isolation monitors.

BiomedRx provides annual inspection and recertification if isolated power systems and line isolation monitors. We perform a thorough inspection of your electrical system and line isolation monitor, and provide you with the documentation required to satisfy Joint Commission, NFPA99, and other regulatory requirements. We even provide video documentation of our services. If you have questions about our isolated power system inspection and recertification services, call us today at (424) 204-2382.

Here is a video documentation of a previous isolated power system inspection performed at the Veterans Administration Hospital, Los Angeles

Lately there has been controversy in the hospital engineering community concerning the use of isolated power systems and the 2012 changes in the National Fire Protection Association standard, NFPA 99.

Section 3.3.89 of NFPA99 2012 defines an Isolated Power System Testing Services as "A system comprising an isolation transformer or its equivalent, a line isolation monitor, and its ungrounded circuit conductors."

Section 3.3.9 of NFPA99 2012 defines a Line Isolation Monitor as "A test instrument designed to continually check the balanced and unbalanced impedance from each line of an isolated circuit to ground and equipped with a built-in test circuit to exercise the alarm without adding to the leakage current hazard." In an isolated power circuit, a ground fault would result in an alarm, but power would not be interrupted.

Section 3.3.184 of NFPA99 2012 defines a Wet Procedure Location as "The area in a patient care room where a procedure is performed that is normally subject to wet conditions while patients are present, including standing fluids on the floor or drenching of the work area, either of which condition is intimate to the patient or staff."

Section of NFPA99 2012 addresses isolated power with regard to Critical Care Areas and states "Where used in locations such as critical care areas, isolated power panels shall be permitted in those locations."

Section of NFPA99 2012 addresses Wet Procedure Locations.

Section of NFPA99 2012 states "Wet procedure locations shall be provided with special protection against electric shock."

Section of NFPA99 2012 states "Operating rooms shall be considered to be a wet procedure location, unless a risk assessment conducted by the health care governing body determines otherwise.

This is the most controversial section. A risk assessment by the health care governing body can in fact deem an operating room not to be a wet procedure location. This would be contingent on interpretation of the mopping of the floor which occurs between cases as "drenching", as defined in Section 3.3.89 above.

Section of NFPA99 2012 states "The use of an isolated power system (IPS) shall be permitted as a protective means capable of limiting ground-fault current without power interruption. When installed, such a power system shall conform to the requirements of"

Section of NFPA99 2012 states "Operating rooms defined as wet procedure locations shall be protected by either isolated power or ground fault circuit interrupters."

Section of NFPA99 2012 addresses Isolated Power

Section of NFPA99 2012 states "The system shall be permitted to be installed where it conforms to the performance requirements specified in

Section of NFPA99 2012 addresses Line Isolation Monitors

Section of NFPA99 2012 states "The monitor shall be designed such that a green signal lamp, conspicuously visible in the area where the line isolation monitor is utilized, remains lighted when the system is adequately isolated from ground; and an adjacent red signal lamp and an audible warning signal (remote if desired) shall be energized when the total hazard current (consisting of possible resistive or capacitive leakage currents) from either isolated conductor to ground reaches a threshold value of 5.0 mA under normal line voltage conditions. The line isolation monitor shall not alarm for a fault hazard current of less than 3.7 mA.

This is interesting, as many of the Line Isolation Monitors still in use are older, often analog units that are set to alarm at only 2 mA. These units must be replaced immediately, as it is a violation of code to use them.

Section of NFPA99 2012 addresses Performance Criteria and Testing for Isolated Power System Testing Servicess.

Section of NFPA99 2012 Line Isolation Monitor Tests states "The line isolation monitor (LIM) circuit shall be tested after installation, and prior to being placed in service, by successively grounding each line of the energized distribution system through a resistor whose value is 200 x V (ohms), where V equals measured line voltage. The visual and alarms shall be activated."

Section of NFPA99 2012 addresses Maintenance and Testing of the Electrical System.

Section of NFPA99 2012 states "The LIM circuit shall be tested at intervals of not more than 1 month by actuating the LIM test switch. For a LIM circuit with automated self-test and self-calibration capabilities, this test shall be performed at intervals of not more than 12 months. Actuation of the test switch shall activate both visual and audible alarm indicators.

Section of NFPA99 2012 addresses Record Keeping.

Section of NFPA99 2012 states "A record shall be maintained of the tests required by this chapter and associated repairs or modification.

Section of NFPA99 2012 states "At a minimum, the record shall contain the date, the rooms or areas tested, and an indication of which items have met, or have failed to meet, the performance requirements of this chapter.

Section 6.3.4..2.2 of NFPA99 2012 Isolated Power System Testing Services (Where Installed) states "A permanent record shall be kept of the results of each of the tests.

Here is a video documentation of a previous isolated power system inspection performed (in English and Spanish) at Kindred Hospital in South Bay, California.

BiomedRx maintains the highest standard of service, reporting and documentation in the healthcare industry. We perform the annual inspection of your isolated power systems, verify the operation/calibration of your line isolation monitors, and provide the necessary documentation to satisfy The Joint Commission and NFPA 99 requirements. In addition, we provide video documentation of all service visits. You can learn more about hospital isolated power distribution systems on a .PDF file you can download here.

Please find the reasons to keep Isolated Power in all Operating Rooms:

1. Reduced Shock Hazard

2. Continuity of Power

3. Line Noise Reduction, the transformer acts as an electrical filter.

4. Advance warning system of what their equipment condition is.

5. Reduced Fire Hazard

6. Extra level of protection will keep down liability claims.

Here is a video documentation of a previous isolated power system inspection performed Fountain Valley Hospital, California.

In addition to biomedical engineering and equipment maintenance services, BiomedRx now offers testing and certification of isolated power systems and line isolation monitors. BiomedRx can bring any healthcare facility into compliance with NFPA code requirements.

BiomedRx can perform the annual testing and re-certification of your system if it passes, and we can provide replacement or retrofitting of your system to bring it into compliance if it doesn't.

BiomedRx testing of isolated power systems exceeds the requirements of NFPA 99 and Our testing service includes:

Testing of ungrounded isolated power systems and wiring.

A complete inspection of all devices for polarity.

Verification that all applicable sections of code requirements are being met.

Confirmation that the impedance to ground of both conductors of the isolated system exceeds 200,000 ohms when installed. Document what corrective action that needs to be completed to meet that standard.

Log voltage and millivolt readings for criteria for acceptability for new construction or existing rooms.

Line isolation monitors will be tested and all readings will be taken to make sure that they not only are working but working within the specifications of the code requirements from when they were installed.

Upon completion of testing, a technician shall meet with hospital medical and maintenance staff to explain the operation of isolated power systems; explain alarm procedures and answer any questions.

Periodic testing and logging for future test required by NFPA 99 will be explained to maintenance staff.

After all tests have been successfully completed, a written certification will show that all systems comply with codes, good installation practices and specifications. We will also provide written confirmation that the testing logbooks have been delivered to the hospital maintenance staff and that they are up to date.

Training: "Administrative authorities should ascertain that electric maintenance personnel are completely familiar with the function and proper operation of ungrounded electric circuits." For liability and operation, has your hospital personnel, that are now maintaining your Isolated Power System Testing Servicess, been trained by a proper instructor? Many hospitals had training when the equipment was first installed but after many years those individuals are no longer with the hospital. BiomedRx can train your current maintenance staff on any manufacturer's isolated power systems. NFPA 99 states "The Health Care Facilities shall provide programs of continuing education for its personnel.

Here is a video documentation of a previous isolated power system inspection performed at Beach District Surgery Center, in California.

BiomedRx services isolated power systems and line isolation monitors manufactured by:

Crouse Hinds
Electromagnetic Industries (EMI)
Federal Pacific
Federal Pioneer
General Electric
Hospital Systems
Measurement Engineering Limited (MEL)
Post Glover
Russell & Stoll
Square D

Here is a video discussing recent controversies concerning the use and inspection of isolated power systems and line isolation monitors.

BiomedRx has isolated power system and line isolation monitor testing and service centers in Alabama, Alaska, Arizona, Arkansas, California (Los Angeles, San Diego, San Francisco), Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachussetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming and Puerto Rico.