Line Isolation Monitor Testing
Expert LIM testing, calibration, and installation to keep your isolated power systems compliant and your patients safe.
- ASSE 6010, 6020, 6030, 6040 certified technicians
- NFPA 99 compliant testing and calibration
- Emergency certification and calibration available
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Our LIM Services
The LIM continuously monitors impedance to ground in isolated power systems and warns of ground faults before they harm a patient. Our certified technicians keep yours code-compliant and trusted.
- ASSE 6010, 6020, 6030, 6040 certified technicians
- NFPA 99 compliant testing and calibration
- Emergency certification and calibration available
- LIM installation, retrofit, and replacement
- Remote annunciator upgrades
- Permanent test records and maintenance log setup
- Bonded & insured — SAM/DUNS registered
- Nationwide coverage — all 50 states
Need LIM Testing?
NFPA 99 compliant testing, calibration, and emergency replacement. Call us or request a free quote.
Craftsmanship Warranty Included
Every service is backed by our craftsmanship warranty — we stand behind our work.
Frequently Asked Questions
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Need LIM Testing or Replacement?
Our certified technicians provide NFPA 99 compliant LIM testing, calibration, and emergency replacement. Call now or request service.
ASSE 6010 · 6020 · 6030 · 6040 Certified | Bonded & Insured | SAM/DUNS Registered
NFPA 99 LIM Testing Requirements
When is testing of Line Isolation Monitors required?
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 × V (ohms). The visual and audible alarms shall be activated.
After any repair or renovation to an electrical distribution system, the LIM circuit shall be tested in accordance with 6.3.3.3.2 to make sure the integrity of the LIM is still working and has not been altered.
The LIM circuit shall be tested at intervals of not more than 1 month by actuating the LIM test switch. For a LIM with automated self-test and self-calibration capabilities, this test shall be performed at intervals of not more than 12 months.
Electrical safety test instruments shall be tested periodically, but not less than annually, for acceptable performance. The LIM is a test instrument per 3.3.97 definitions and needs to be tested to manufacturer and NFPA specifications.
A permanent record shall be kept of the results of each of the tests. Joint Commission will look for your test log to make sure it is being done on time and correctly.
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.
LIM Alarm Checklist
What to do if a Line Isolation Monitor is in alarm
If you just plugged a piece of equipment in and the panel alarms, unplug the equipment. If the panel stops alarming, red tag the equipment and remove from the operating room.
If the panel alarms during an operation, visually inspect the operating room. Look for cords in fluids or carts on line cords. If the equipment is not maintaining life support, try unplugging it. If the alarm stops, replace and red tag the equipment for maintenance.
If the panel alarms and you can't see a visual reason, silence the LIM and call maintenance. An alarm does not mean an unsafe condition exists — it means if another fault occurs, a shock is possible. Once the case is completed, the room must be closed until the problem is resolved. Note what equipment was on when the panel alarmed.
With the patient out of the room, maintenance can turn off one breaker at a time while watching the LIM. When it drops out of alarm, note that circuit. Turn the breaker back on, then unplug equipment one at a time until the LIM clears. Red tag defective equipment.
If the panel will not drop out of alarm after all circuit breakers are turned off, the LIM is defective. Remove and replace the LIM. The operating room is down until replacement. It is best practice to have a spare LIM in stock.
Call Medical Testing Solutions at (754) 315-1078 or submit the form if the problem cannot be solved, or for replacement LIM's and parts.