Mike Dolt Enterprises
Mike Dolt Enterprises
User: Andy Sherrill
Asked on: Saturday, March 26, 2011 at 10:47 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:21 am EDT
Question: I am working on a dental clinic that has (2) small x-ray units that require 120 V, 20 Amp circuits and (2) units that require 220 V, 20 Amp circuits. The larger units show on their website that the load is 2.8 KW. My question is: Do these small units have to have a disconnect? I have not ever seen a dentist office in my area that has disconnects on these small units, but the Code seems to require them?
NEC Requirement for Disconnects
According to the National Electrical Code (NEC), all electrical equipment must have a means of disconnect within sight of the equipment. This includes dental x-ray units.
Exception for Small Equipment
However, the NEC provides an exception for certain small equipment that is: Plug-connected 1/4 hp or less (for motors) 15 or 20 amps Less than 50 volts or 100 watts (for lighting or heating)
Application to Dental X-Ray Units
Based on the information provided, it is unclear whether the small dental x-ray units in question meet the criteria for the exception. If the units are plug-connected, have a rated current of 20 amps or less, and are less than 100 watts, then they may not require a disconnect under the NEC exception.
Code Interpretation
The NEC does not provide specific guidance on whether or not small dental x-ray units require a disconnect. However, some local authorities having jurisdiction (AHJs) may require disconnects on all electrical equipment, regardless of size.
Best Practice
It is generally considered best practice to provide a disconnect for all electrical equipment, including small dental x-ray units. This provides a convenient and safe means of de-energizing the equipment for servicing or maintenance.
Conclusion:
While the NEC may not explicitly require a disconnect for small dental x-ray units, it is advisable to confirm the requirements with your local AHJ. Installing a disconnect is a safe and convenient practice that can provide additional protection for both patients and staff. Flag for review