UFC 3 -520-01
June 10, 2002
5-5.1.5 Molded case switches can be used for applications in which only equipment
isolation is necessary. Electrical protection is still required to be available from
upstream devices. Nonfused disconnect switches can also be used as switches.
Do not use series-combination rated breakers. This type of design
guarantees loss of entire panelboards or load centers in response to a short circuit.
Also, inappropriate breaker replacements wi ll invalidate the rating and create the
potential for equipment or personnel damage if a short circuit occurs.
Circuit breakers are preferred over fuses, fusible disconnect switches , or
fusible bolted pressure switches to satisfy electrical protection requirements, unless the
available fault current requires the higher interrupting rating of these devices.
Ensure circuit breakers used as switches in 120 volt and 277 volt lighting
circuits are listed for the purpose and are marked "SWD" or "HID" (switching duty or
high-intensity discharge lighting) in accordance with NEC Article 240.83(D ) (2002
Ensure circuit breakers intended to protect multiple motor and combination
load installations associated with heating, air conditioni ng, and refrigeration equipment
are marked "Listed HACR Type" in accordance with NEC Article 430.53(C) (2002
Edition) requirements for group installations. Also, a circuit breaker with this marking is
suitable only for use with equipment marked to indicate that an HACR circuit breaker is
Provide arc-fault circuit interrupter protection in accordance with NEC Article
210.12 (2002 Edition). This requirement applies to all branch circuits supplying 125
volt, single -phase, 15 - and 20- ampere outlets installed in dwelling unit bedrooms.
5-5.7.1 Panelboards are commonly used as a means of electrical distribution
between main or sub -distribution points and individual connected loads. Different types
of panelboards are commonly available:
5-18.104.22.168 Service equipment panelboards--available for loads up to 1,600 amperes.
These panelboards usually contain up to six breakers (or fused switches or fusible
bolted pressure switches) connected to the incoming mains.
5-22.214.171.124 Feeder distribution panelboards-- usually contain circuit overcurrent devices
rated at more than 50 amperes to protect subfeeders to smaller branch circuit
5-126.96.36.199 Load center panelboards-- normally rated up to 1,200 amperes at 600 volts or
less. Similar to feeder distribution panelboards, these contain three-phase control and
overcurrent devices for motor or power-circuit loads. Apply switchboard designs for
load requirements greater than 1,200 amperes.