New section addressing when surge protection is provided, where the surge protection must be provided, and the type of surge protection to be provided. It also addresses replacements and surge protective device ratings.
(A) Surge-Protective Device
A feeder that supplies any of the following must have an SPD installed in or adjacent to the distribution equipment connected to the load side of the feeder that contains branch circuit overcurrent protective devices that supply these locations:
- Dwelling units
- Dormitory units
- Guest rooms and guest suites of hotels and motels
- Areas of nursing homes and limited-care facilities used exclusively as patient sleeping rooms
The length of the conductor connecting the surge protective device to the equipment is critical to its performance. This section requires that the surge protective device be installed in the equipment or immediately adjacent to it.
The device installed to meet these requirements must be a Type 1 or Type 2 surge protective device. A type 1 devices is designed to be permanently connected between the secondary conductors of the service transformer and the line side of the service disconnect overcurrent device. A Type 2 device is designed to be permanently connected on the load side of the service disconnect overcurrent protective device. A type 3 device is intended to be installed at the point of utilization. Finally a Type 4 device is a component found within assemblies such as industrial control panels.
When distribution equipment that is supplied by this feeder for the locations identified in this Section is replaced, all of these requirements apply.
The SPD must have a nominal discharge current rating not less than 10kA.
SPD Lead Length Video
This video demonstrates the importance of surge protective devices and illustrates the protection provided. A surge protective device provides protection to electronic components and whether they are safety related components or not, the NEC should be there to provide that protection.
Article 100 Surge Protective Device (SPD)
225.42 Surge Protection
230.67 Surge Protection
Article 242 Overvoltage Protection