Type 1 or type 2 Surge-Protective Devices (SPD’s) are now required for new & replaced service equipment that supplies dwellings. This protects devices not already protected by point-of-use SPD’s from damage due to surges.
What are SPD’s?
These devices have been installed in commercial services for some time & have been referred to as TVSS’s or Transient Voltage Surge Suppressors. The 2009 edition of UL 1449 changed the name from TVSS to SPD or Surge Protection Devices. These devices limit voltage spikes or surges on the electrical system which are caused by lightning strikes, or from large inductive loads, such as motors, being turned on & off. When magnetic fields are generated, they expand & collapse when a motor is turned on and off. It is this expanding & collapsing magnetic field that creates voltage spikes. SPDs are basically filters that protect the electrical equipment & people from these sudden voltage spikes.
The code committee statement regarding the new code section expressed that this code change addresses the need for surge protection to properly protect the sensitive electronics present in most modern appliances as well as safety devices (AFCI, GFCI and smoke/carbon monoxide detection) and other equipment commonly found in dwellings. Additionally, Article 242 has been added and replaces articles 280 and 285 in the 2017 Code.
Location: The SPD shall be an integral part of the service equipment or shall be located immediately adjacent thereto.
Exception: The SPD shall not be required to be located in the service equipment if located at each next level distribution equipment downstream toward the load.
What is the difference between type 1, 2 & 3 SPD’s?
Type 1 SPD is a hardwired, permanently connected SPD which may be installed on the utility side of the main service overcurrent protective device (i.e. before the main breaker at the service), or it may be installed after the main breaker. The Type 1 SPD can be installed on the line side or load side of the main breaker.
Type 2 SPD is also a hardwired, permanently connected SPD which must be installed after the main service overcurrent protective device. This means it must be installed on the load side of the main breaker.
Type 3 SPDs are point-of-use devices and are still recommended for the protection of computers, TV’s and other electronic devices, but are outside the scope of the Article 230.67 requirements and cannot be used to comply with the provisions of this section.