Chapter 8 of the 2005 edition of NFPA 99 addresses the requirements of electrical equipment used in health care facilities, such as portable x-ray systems

Chapter 8 of NFPA 99 (2005 edition) addresses the requirements of “Electrical equipment” used in health care facilities. Below are some of the commonly referenced requirements for patient care-related electrical appliances.

GROUNDING/DOUBLE INSULATION

Electrically powered patient care appliances that are not double insulated when used in the patient care vicinity should be provided with a three-wire power cord and a three-pin grounding-type plug (8.4.1.2.1.1).

Double-insulated patient care electrical appliances are allowed to have two conductor cords (8.4.1.2.2).

CHASSIS LEAKAGE CURRENT

The chassis leakage current for cord-connected patient care appliances should not be more than 300 µA (8.4.1.3.5.1). Chassis leakage current between 300 µA and 500 µA is allowed for existing or special equipment like mobile x-ray machines if the following two conditions are met:

  • The grounding conductor is intact; and
  • A documented maintenance schedule is established to verify the reliability of the grounding connection. The maintenance schedule and interval for testing should be based on the intensity of appliance use and prior test data (8.4.1.3.5.2).

RESISTANCE

For the patient care electrical appliances used in the patient care vicinity, the resistance between the chassis (or any exposed conductive surface) and the ground pin of the attachment plug should be less than 0.50 ohm. The cord should be flexed at its connection to the strain relief and the attachment plug when measuring resistance (8.4.1.3.2).

TESTING INTERVALS

Testing intervals for patient care electrical appliances should be determined by their location/area of normal use, but should not exceed 12 months for general care areas, 6 months for critical care areas, and 6 months for wet locations (8.5.2.1.2.2).

An exception allows the facility to implement shorter or longer intervals of testing based on the equipment’s maintenance history. Another exception allows that facility-owned household and other appliances that are used in the patient care vicinity but are not intended to contact the patient should be tested at intervals determined by the facility.

NONPATIENT AREAS

For nonpatient care-related electrical appliances, some of the commonly referenced requirements follow:

The chassis leakage current for nonpatient care appliances (such as housekeeping or maintenance appliances) should not be more than 500 µA when they are used in the patient care vicinity, and during normal use they can come in contact with patients (8.4.2.2.1.1).

Household or office appliances without grounding conductors are allowed if they are not located within the patient care vicinity. Double-insulated appliances are allowed in the patient care vicinity (8.4.2.2.1.2).

Adapters and extension cords are permitted to be used (8.5.2.1.7.1). The wiring of extension cords should be tested for physical integrity, polarity, and continuity of grounding at the time of assembly and periodically thereafter (8.5.2.1.7.3). The three-to-two-prong adapters are not allowed to be used (8.5.2.1.7.2).


Arif Subhan, MS, CCE, is a senior clinical engineer, Masterplan, Chatsworth, Calif; adjunct assistant professor, biomedical engineering, University of Connecticut; and a member of 24×7’s editorial advisory board. For more information, contact .

Review Questions

  1. According to NFPA 99, electrically powered appliances that are not double insulated when used in the patient care vicinity should be provided with____.
    1. A two-conductor cord and a two-pin plug
    2. A three-wire power cord and a three-pin grounding-type plug
    3. A three-wire power cord and a two-pin plug
    4. A two-wire power cord and a three-pin grounding-type plug
    5. None of the above

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  2. According to NFPA 99, the chassis leakage current for cord-connected patient care appliances should not be more than____.
    1. 300 μA
    2. 100 μA
    3. 300 mA
    4. 600 μA
    5. None of the above

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  3. According to NFPA 99, for the patient care electrical appliances used in the patient care vicinity, the resistance between the chassis (or any exposed conductive surface) and the ground pin of the attachment plug should be less than ____ ohm.
    1. 0.05
    2. 0.25
    3. 0.50
    4. 1.25
    5. None of the above

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  4. According to NFPA 99, the chassis leakage current for nonpatient care appliances (such as housekeeping or maintenance appliances) should not be more than____.
    1. 500 μA
    2. 300 μA
    3. 500 mA
    4. 100 μA
    5. None of the above

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  5. According to NFPA 99, the following statements are true except____.
    1. Adapters and extension cords are permitted to be used.
    2. The three-to-two-prong adapters are not allowed to be used.
    3. Household or office appliances without grounding conductors are allowed if they are not located within the patient care vicinity.
    4. Double-insulated patient care electrical appliances are allowed to have two conductor cords.
    5. All patient care electrical appliances should be tested at 12-month intervals.

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