Restoring safe operation to aging infrastructure, the 2120 is a 20-amp NES series breaker with a fixed thermal-magnetic trip mechanism. It installs into classic Federal Pacific Stab-Lok load centers, providing an exact physical match that avoids complex retrofits. The N-frame device handles up to 14kAIC at 120VAC and 5kAIC at 125VDC, making it suitable for diverse residential or commercial loads. Facility managers can also cross-reference this legacy hardware with the UBIF20N substitute.
Shunt Trip, Undervoltage Release, Bell Alarm, Auxiliary Switch
Accessories
Load Side Lugs Included
Standards
UL 489, NEMA AB 1
Approval
UL
Temp Rating
40C
Construction Features
Non-Interchangeable Trip
Product FAQs
6 answers
Which electrical panels accept the Federal Pacific NES2120 circuit breaker?
The NES2120 is a plug-on breaker designed specifically for legacy Federal Pacific Electric (FPE) Stab-Lok load centers and NE-S frame panelboards. It will not fit in modern load centers from other manufacturers.
Are there safety concerns associated with Federal Pacific Stab-Lok breakers?
Yes. Federal Pacific Electric (FPE) Stab-Lok panels and breakers have a well-documented history of failing to trip during overcurrent or short-circuit events, creating a severe fire hazard. Independent testing and industry consensus strongly recommend replacing the entire FPE panel with a modern, UL-listed load center rather than installing replacement breakers.
What wire sizes are compatible with the NES2120 lug terminals?
The lug terminals on the NES2120 accept wire gauges from 14 AWG to 10 AWG. When wiring a 20-amp branch circuit, ensure the conductor size complies with current National Electrical Code (NEC) requirements for the specific application and insulation type.
How does the thermal-magnetic trip unit function on the NES2120?
The fixed thermal-magnetic mechanism provides dual protection: the thermal element responds to sustained overloads with a long-time delay, while the magnetic element provides an instantaneous trip response to clear short circuits.
Can the NES2120 be used in DC applications?
Yes, in addition to its 14kA at 120VAC interrupt rating, the NES2120 is rated for 5kA at 125VDC, allowing it to be used in compatible low-voltage direct current circuits.
Are there newly manufactured replacements for the Federal Pacific 2120?
Yes, Connecticut Electric produces modern, ETL-listed replacement breakers (such as the UBIF series) engineered to fit FPE Stab-Lok panels. However, many licensed electricians advise against installing new breakers in legacy FPE panels due to the underlying safety risks of the panel bus design.
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