Connecticut Electric UBIF0250N 50 Amp Circuit Breaker for Level 2 EV Charging
The Connecticut Electric UBIF0250N is a 50A, 2-pole circuit breaker designed for Federal Pacific Electric panels. It ensures reliable performance for 240V 40 A Level 2 EV chargers, offering safety and compliance with NEC standards.
The Connecticut Electric UBIF0250N is a 50 Amp, 2-pole, thin-series Stab-Lok circuit breaker I recommend for installing 240V 40A Level 2 EV chargers or amperage adjusted Level 2 EV chargers that support 40A adjustments – especially for installation in older homes with original Federal Pacific Electric (FPE) load centers that still use Stab-Lok breaker panels.
As an EV charger installer, I often run into homeowners looking to upgrade to a 9.60 kW EV charger or a 240V 40A Level 2 EV charger, but their homes still rely on outdated FPE panels. Replacing the panel isn’t always feasible, and that’s where the UBIF0250N becomes the ideal solution. This breaker is newly manufactured, not refurbished or salvaged by Connecticut Electric, and it’s ETL listed to UL Standard 489 for both the U.S. and Canada. It’s a safe, compliant choice when wiring EV charging circuits for a 40A EV charger in legacy FPE panels.
The UBIF0250N is classified as a direct replacement for the FPE NC250 thin-style 2-pole breaker, making it fully compatible with older Stab-Lok panels. This eliminates the guesswork during installs and helps ensure compliance with NEC requirements for residential EV charging. Its 10,000 AIC interrupt rating adds another layer of safety and reliability when wiring circuits in older homes with limited electrical upgrades.
We tested the UBIF0250N on a dedicated 50A plug-in EV charger branch circuit using a NEMA 14-50 outlet and an Evgoer J1772 40A EV Charger, rated for a full 9.60 kW EV charging load at 240V.
We installed the UBIF0250N in a dedicated 50A EV charging circuit with a NEMA 14-50R outlet housed in a NEMA 14-50 weatherproof cover. The circuit used 6 AWG solid copper THHN conductors in ¾-inch conduit, with grounding bonded to the panel’s busbar as shown in the wiring diagram below:
Installation into the original Federal Pacific Electric (FPE) Stab-Lok panel was seamless, the breaker snapped firmly into place, avoiding the loose fit common with many aftermarket replacements.
Its plug-in design suitable for DIY 40 A EV charger installations created a secure connection, and the high-quality copper internals handled the 9.60 kW EV charger load from our 240V 40A Level 2 EV charger without the 50A EV charger circuit breaker tripping, heat buildup, or voltage drop. Over 25–30 full charging sessions using the Evgoer J1772 40A EV charger – including overnight charges in high ambient temperatures – the breaker delivered a stable, uninterrupted performance with no chatter or thermal fatigue. That kind of consistent, cool operation is especially critical in older Federal Pacific panels, which are known for contact degradation and reliability issues under sustained high-current loads.
Wiring the UBIF0250N Breaker for a 240V Level 2 EV Charger
When installing a 240V Level 2 EV charger using the Connecticut Electric UBIF0250N breaker in an original Federal Pacific Electric (FPE) Stab-Lok load center, proper wiring is critical to ensure safe operation and compatibility with legacy panels. Although we used a NEMA 14-50 circuit to test the UBIF0250N breaker with an Evgoer J1772 40A EV Charger, other wiring configurations can also be used for plug-in EV charger installation or hardwired EV charger installations of 40A EV chargers. The UBIF0250N serves as a direct replacement for old Stab-Lok 2-pole 50A breakers, making it a viable option for 40A EV charger installations in homes with the original Federal Pacific Electric (FPE) Stab-Lok load center.
Below are the most common wiring methods used with the UBIF0250N breaker, including configurations and wiring diagrams for code-compliant EV charger installations.
EV Charger Wiring – 240V (4-Wire: L1, L2, Neutral, Ground) – UBIF0250N Breaker
The Connecticut Electric UBIF0250N breaker supports 240V plug-in Level 2 EV chargers using a NEMA 14-50 outlet. Compatible EV chargers include the plug-in Emporia Pro EV Charger, Lectron Level 2 Tesla Portable Charger, and many other NEMA 14-50 EV chargers. The 4-Wire: L1, L2, Neutral, Ground configuration is the most popular option for plug-in EV charger installations and is widely used in older homes with FPE Stab-Lok panels.
This same 4-wire configuration is also commonly used for hardwired installations of EV chargers that support 4-wire terminal connections. Licensed electricians and certified EV charger installers also use this circuit when converting plug-in NEMA 14-50 EV chargers to hardwired setups. Installation typically involves 6 AWG solid copper conductors: two hot wires connected to the UBIF0250N breaker, with the neutral and ground terminated at the panel’s busbars — as shown in the wiring diagram below:
Compatible Level 2 EV Chargers for This Wiring Setup
EV Charger Wiring – 240V (3-Wire: L1, L2, Ground) – UBIF0250N Breaker
This configuration is commonly used for the installation of hardwired Level 2 EV chargers that allow 3-Wire: L1, L2, Ground terminal connection in homes with older FPE Stab-Lok breaker panels, especially for EV chargers that operate at 240V and do not require a neutral. It’s ideal for hardwired 40A EV chargers or units that allow amperage adjustment to 40A, such as the hardwired Emporia Pro EV Charger and Tesla Wall Connector.
3-wire (L1, L2, Ground) EV branch circuit configurations on older FPE Stab-Lok breaker panels also support plug-in EV charger installations, such as NEMA 6-50 EV chargers like the NEMA 6-50 Grizzl-E Smart EV Charger and other NEMA 6-50-compatible models designed for 240V-only operation without a neutral.
The 3-Wire: L1, L2, Ground EV charger branch circuit typically uses 6 AWG solid copper conductors: two hot wires from the UBIF0250N double-pole breaker and one ground wire connected to the panel’s ground bar — as shown in the wiring diagram below. No neutral is required, and the setup remains safe and fully NEC-compliant for 240V-only EVSE installations.
Compatible Level 2 EV Chargers for This Wiring Setup
The Enphase IQ 50 40 Amp Smart EV Charger delivers 9.6kW of power at 240V with a hardwired installation and a 25ft cable. Featuring Wi-Fi connectivity, a ruggedized J1772 connector, and safety certifications, it ensures reliable, efficient charging. Backed by a 5-year warranty, it's ideal for home use and future-proofing.
The Emporia Level 2 EV Charger with NACS delivers fast, reliable charging for Tesla and NACS vehicles. It offers up to 46 miles of range per hour, features easy installation, and is UL-listed for safety. Smart charging capabilities and durable construction make it a great value at a competitive price.
EV Charger Wiring – 240V (3-Wire: L1, L2, Neutral, No Ground) – UBIF0250N Breaker
Some legacy FPE installations still use 3-wire configurations where the neutral was bonded to the ground at the panel, and a separate ground wire was not run. While this wiring method (L1, L2, Neutral) can still be found with older NEMA 10-50 outlets used for NEMA 10-50 EV chargers, it is not considered safe by today’s NEC standards—especially for hardwired EV charger installations. Use this configuration only if the EV charger specifically supports it and local code explicitly permits it — as shown in the 3-Wire: L1, L2, Neutral, No Ground – UBIF0250N breaker EV charger branch circuit wiring diagram below:
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