One of the changes in the 2014 edition of the National Electrical Code (NEC) was a new section in Article 110 pertaining to lockable disconnecting means. This is significant because a number of sections throughout the Code contain requirements for disconnecting means. It is important to have a good understanding of these requirements.


For example, 430.102(B) and (B)(1) state a disconnecting means is required to be located in sight from the motor location and the driven machinery location. Article 100 is needed to clarify the meaning of the term “in sight from” used in this section. As stated in Article 100, where the NEC specifies that one piece of equipment shall be “in sight from,” “within sight from,” “within sight of,” and so forth, the specified equipment is to be visible and not more than 50 feet from the other. In accordance with the main rule in 430.102(B)(1), a disconnecting means (for the motor) shall be visible and located no more than 50 feet from the motor (see Figure 1).


The section in 430.102(B) continues by saying the same disconnecting means used to disconnect the controller required by 430.102(A) can also serve as the disconnecting means for the motor if it is in sight from the motor location and the controller location. One method of complying with this section is to use a separate disconnecting means located ahead of the motor controller and within sight of the motor. The term “motor controller” referenced in the Code is usually called a motor starter out in the field. Another way to comply with this section is to install a combination motor controller within sight of the motor. A combination motor controller is both a motor controller and a disconnecting means in one enclosure.


Where meeting certain conditions, it is not required to have the disconnecting means within sight of the motor. As stated in the exception under 430.102(B)(1) and (2), the motor disconnecting means shall not be required under either of two conditions that are stated in this exception, provided the controller disconnecting means required in 430.102(A) is lockable in accordance with new Section 110.25.


Before the 2014 NEC, this exception contained quite a bit more text. As stated in the same exception in the 2011 NEC, the motor disconnecting means shall not be required under either condition (a) or (b), provided the controller disconnecting means required in accordance with 430.102(A) is individually capable of being locked in the open position. This continued by saying the provision for locking or adding a lock to the controller disconnecting means shall be installed on or at the switch or circuit breaker used as the disconnecting means and shall remain in place with or without the lock installed. 


Prior to the 2014 NEC, every section that allowed a remote disconnecting means that was lockable in the open position had to specify the provision for locking or adding a lock. In 2014, all the sections allowing a remote disconnecting means simply state the disconnecting means shall be lockable. In accordance with 110.25, where a disconnecting means is required to be lockable open elsewhere in the Code, it shall be capable of being locked in the open position and the provisions for locking shall remain in place with or without the lock installed. While Section 110.25 is new, the specific locking provisions are not.


There are sections throughout the Code that state the disconnecting means is required to be lockable in the open position. This simply means when the disconnecting means is in the open (or off) position, a lock can be installed to keep the disconnecting means from being closed (or energized). At first, the second sentence in 110.25 seems a bit peculiar, but it is actually precise and to the point. 


A little background information will help clarify the last sentence in 110.25. In the 1999 NEC, the exception under 110.102(B) stated the disconnecting means had to be lockable in the open position but did not specify anything about the locking device or mechanism. In the 2002 NEC, a sentence was added stating the provision for locking or adding a lock to the disconnecting means had to be permanently installed on or at the switch or circuit breaker used as the disconnecting means. If a safety switch or disconnect was installed after Jan. 2, 1990, then it should be capable of accepting a lockout device. When the handle of a safety switch is in the open (or off) position, there will be a hole or opening for a lock. When a lock is installed, the handle cannot be closed and, therefore, the equipment cannot be energized without cutting off the lock. Since the capability of accepting a lockout device are built into a safety switch, the provisions for locking are permanently installed.


There are all types of devices installed on circuit breakers or panel covers for locking the breaker in the open (or off )position but very few of these would be considered permanently installed. In the 2005 NEC, text was added to the exception under 110.102(B) to clarify the types of devices that would and would not be permitted. This text is essentially the same as the last sentence in 110.25, which says the provisions for locking shall remain in place with or without the lock installed. There are all types of devices manufactured for the purpose of locking out a de-energized circuit breaker. Some of these devices are placed on the circuit breaker underneath the panel cover. Some are placed on the back or inside the panel cover. The requirement in 110.25 says the provisions for locking (or the locking device itself) have to remain in place even when the lock is not installed. The devices just mentioned will remain in place without a lock.


Some devices are temporarily attached to the handle of a circuit breaker that has been turned off. After the device is attached to the handle of the circuit breaker, a lock is installed to keep it in place and to keep the circuit breaker de-energized until the lock is removed. In order to reenergize the circuit breaker, the temporary device has to be removed. Devices that only remain in place with the lock are prohibited when the Code says the provisions for locking shall remain in place with or without the lock installed. Although these temporary devices are prohibited, they are permitted when energized conductors and circuit parts need to be locked out or locked in the off position for electrical safety.


There are more than 40 references in the NEC to 110.25, and a good example can be found in Section 450.14, new in the 2011 NEC. As stated in the first sentence, transformers, other than Class 2 or Class 3 transformers, shall have a disconnecting means located either in sight of the transformer or in a remote location. It starts by saying a disconnecting means is required and can be located either within sight of the transformer or not within sight of the transformer. (Many times the transformer disconnecting means is located within sight of the transformer.) Quite often, a safety switch or disconnect switch is installed as the transformer disconnecting means. If located within sight of the transformer, the disconnecting means is not required to be capable of being locked in the open position. However, if a new safety switch is installed, it will need to be manufactured with the capability of being locked in the open position. Those locking provisions will remain in place even when no lock is installed (see Figure 2).


As just mentioned, the transformer disconnecting means can be located somewhere other than within sight of the transformer. The second sentence in 450.14 says that if the disconnecting means is not located within sight of the transformer, the disconnecting means shall be lockable in accordance with 110.25, and its location shall be field-marked on the transformer.


For example, a transformer has been installed and the disconnecting means is not within sight. A fused switch in a remote switchboard will be used to supply power to the transformer. Because the disconnecting means is in a remote location, it shall be capable of being locked in the open position and the provisions for locking shall remain in place with or without the lock installed. In the switchboard supplying power to this transformer, the provisions for locking are manufactured into the on/off handle so the provisions for locking will remain in place. To comply with 450.14, the location of the disconnecting means for the transformer shall be field-marked on the transformer (see Figure 3).


The exception under 110.25 pertains to cord-and-plug connected equipment. With a cord-and-plug connection, the provisions for locking are not required to remain in place without the lock installed. Temporary lockout devices placed over or around an electrical plug with a lock to secure the device are permitted to be used with cord-and-plug connected equipment.


Next month’s column continues the discussion of electrical installation requirements.