Prime Power Currents Issue 02


May 2013, Issue 02

Please save the date of Tuesday June 18th  for our next seminar on Automatic Transfer Switches. Richard Knittel and Pete Torres will continue their tag team approach with both classroom discussion and hands-on demonstration in regards to this critical device in your emergency power systems. We are often asked how should a transfer switch be tested and maintained properly,  and next month we will address exactly  that. A separate invitation will be sent later this week to reserve your seat, and we look forward to seeing you!

Addie Mathes

Line Isolation Monitor Testing

Line IsolationMost people are familiar with Ground Fault Circuit Interrupter (GFCI) type circuit breakers in our homes and workplaces. These circuit breakers protect us when they trip under fault conditions, and interrupt the power to that particular circuit. Have you ever wondered how healthcare workers and patients are protected when power interruptions cannot be tolerated; such as in an operating rooms during open-heart surgery?

It is common knowledge that electrical contacts with ground can cause injury, or even death. However, it might surprise some to know that 70% of the injuries reported in electrosurgery are from electrode burns. This is due to a phenomenon known as capacitive coupling. Capacitive coupling is the electrical connection present at high, but not at low electrical frequencies. When high-frequency current is applied to a patient through an electrosurgical electrode, it can cause significant damage to living tissue in a very short period of time!

There are multiple ways to protect healthcare workers and patients from grounding related injuries in the operating room, but the most prevalent by far is the use of isolated electrical systems. Isolated electrical systems remove AC electricity from the grounded power system through the use of an isolation transformer.

Isolated electrical systems have been in use since the 1930’s. Their primary purpose was to prevent arcs between people and equipment that could potentially ignite flammable gases used for anesthesia.  Flammable anesthetics have been abandoned in the United States since the 1970’s, but isolated power systems remain prevalent because of their superior protection against leakage current, electric shock in “wet” areas and capacitive coupling related injuries. Prior to isolated electrical systems, many operating rooms had grounding grids built into operating room floors.

Today, isolated electrical systems are found in operating and emergency rooms, laboratories, labor and delivery rooms, intensive care and critical care areas as well as radiology and specialty testing areas in healthcare facilities across the United States.

National Electric Code (NEC), Article 517-20(a) states that “all receptacles and fixed equipment within the area of the wet location shall have ground-fault circuit-interrupter protection for personnel if interruption of power under fault conditions can be tolerated, or be served by an isolated power system if such interruption cannot be tolerated…”.

Over the years, the equipment and techniques used to monitor isolated electrical systems have varied. Today, Line Isolation Monitors (LIM’s) are standard equipment in operating rooms. LIMs are devises that continuously monitor the impedance of line to ground in an isolated power system. This is accomplished by constantly monitoring the secondary side of the isolation transformer to see if it couples to ground. In such a scenario, alarms sound to notify healthcare personnel in the room. Usually this signals that surgical electrodes are delivering high frequency current to patients (capacitive coupling), or too many electrical components were plugged in simultaneously that their combined capacitance have coupled to ground. The surgeons and staff can then remove the electrodes, reposition grounding pads, unplug equipment or check connections before injury to staff or patient occurs.

Line Isolation

Information on the application and monitoring of isolated power systems are defined in NFPA 99.  NFPA 99 states:

“Line Isolation Monitor (LIM) circuits shall be tested after installation, repair or renovations. LIM performance testing shall also be periodically (at least every 12 months) and documented.”

“Grounding systems shall be tested after installation and retested after alteration or replacement by voltage and impedance measurements.”

“Receptacles shall be inspected and tested after installation, replacement, or servicing. Receptacle testing shall also be performed periodically (at least every 12 months) and documented.”

Healthcare facilities under the watch of The Joint Commission also know that Environment of Care, Section EC.2.14, states that all critical operating components of the utility system must be inventoried, tested, and documented.

Most LIMs have a self-test and self-calibrating option and only need to be tested annually. Remember that modifications to the isolated power system such as the addition or replacement of receptacles require that independent tests be performed.

Prime Power Services, Inc. provides Line Isolation Monitor testing and reporting to Healthcare customers across the Southeast. We test LIMs with our Bender LT3000 Line Isolation Monitor Testing unit. If you would like us to provide you with a quote to test you LIMs, or would like to add this service to your existing Prime Power Service Agreement, please contact Pete Torres at

Maintenance and Testing for Healthcare Industry – Isolated Power Systems, ESCO Energy Services, Lynn Hamrick
Electrical Safety in the Operating Room, Churchill Livingstone,


Featured Project: Delta Air Lines Switchgear Controls

Featured Project Delta Control Panel
The ATS Control Panel for Delta Air Lines was installed this last week and commissioned on Saturday night.

The system is designed to replace three ATSs controllers in an old General Electric switchgear and monitor the five main electrical substations. The system includes a control console with a large touchscreen called an HMI. The new design came after hours of planning and is very similar to a control station seen in a power plant or on a ship’s helm.

The customer is extremely happy with the installation and our product performed flawlessly at commissioning. This is all due to the hard work and efforts by the Project Engineering team and Technicians.

As the lead electrical engineer on this project, Jonathan Turner designed all the system controls including all the screens for the HMI. Vadim Plagov packaged it all in the box and designed the bracket to mount the HMI.

Rick Rothfuss, Vadim Plagov, Stas Plagov, and our technicians helped Jonathan with the manufacture and installation of the panel. The installation included two weeks of long hours running conduits, pulling and terminating hundreds of wires. More importantly, all this was accomplished working dangerously close to energized components at a live data center. They successfully did not have a single accidental interruption to the facility power.

With the efficient team work and incredible dedication to the details, they achieved to complete the project on time and exceeded the expectations of the customer.

“I would like to personally thank the team for their hard work and efforts in this project. Furthermore, I would like to thank the operations department for the scheduling assistance and the purchasing department for getting us the parts promptly.  

I could not have asked for a better team. The startup took me back to my earlier days of at Prime Power Inc.”

Les M. Gonsalves, PE


Georgia Society of Healthcare Engineers Meeting and Exhibition

Prime Power Presentation

Prime Power Services participated in the 2013 Annual Meeting and Technical Exhibition of the Georgia Society of Healthcare Engineers in March. John Banko and Pete Torres presented, “NFPA 110: Are You In Compliance?” The GASHE meeting had a remarkable turn out for the event in McRae, Georgia and the participation of the hospital engineers and business partners was the largest in years.


Meet Our New Team Member, Samuel Franz

Samuel Franz
Samuel Franz joined the Prime Power Services team on March 4th, 2013. He is our new Inside Strategic Account Manager responsible for inside sales support for both North and South Carolina. Sam is a recent graduate of Shorter University where he played (on scholarship) on the NCAA Division II Soccer Team. His accomplishments led him to be named to the All-Academic Conference Team three years in a row. We welcome him to our team and look forward to his help with the Carolina markets.