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Connecticut Electric UBIF0250N 50 Amp Circuit Breaker for Level 2 EV Charging

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9.2
Expert ScoreRead review

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homeowners looking to upgrade to a 9.60 kW EV charger or a 240V 40A Level 2 EV charger, but their homes still rely on outdated FPE panels.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.

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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:This image serves as a wiring diagram titled "40A EV Charger Wiring Diagram with UBIF0250N Breaker," illustrating the connection of a 40 Amp Level 2 EV charger to a Federal Pacific single-phase 240V electrical panel, adhering to US National Electrical Code (NEC) standards. The diagram shows the main electrical panel receiving power from the utility via three wires entering the top: L1 (Hot 1, black), L2 (Hot 2, red), and N (Neutral, white). These lines connect directly to the active lugs on the main panel breaker situated at the top inside the panel enclosure. A prominent yellow warning sign highlights that these active lugs are continuously live, irrespective of the main breaker's on/off status. Inside the electrical panel, vertical busbars are shown. The incoming L1 and L2 wires feed the main breaker, which in turn feeds the hot busbars where individual circuit breakers are mounted. A Neutral Busbar is shown connected to the incoming white neutral wire. A separate Ground Busbar (labeled G) is also present. An "Electrical Bonding" connection is depicted between the neutral and ground busbars, typical for a main service panel. The Ground Busbar is connected via a green or bare copper "Earth Conductor" wire to an external "Ground Rod" driven into the "Ground/Earth," establishing the system's grounding. A dedicated circuit breaker, specified as a "CB1 - 50A 2P Connecticut Electric (UBIF0250N)", is installed in the panel specifically for the EV charger. This is a double-pole breaker, occupying two slots and connecting to both hot busbars. The wiring for the "240V EV Charger Branch Circuit" exits this dedicated breaker: a black wire (L1) from one pole and a red wire (L2) from the other pole. A green ground wire (G) is connected to the Ground Busbar. These three wires are identified as "EV Charger Circuit Wiring 6 AWG 90C, Copper Wire". They exit the panel enclosure through a fitting labeled "3/4" Conduit". An inset image shows a hand tightening this conduit fitting. A note regarding "Voltage Drop" advises upsizing wires on long runs to keep voltage drop under 3% per NEC. Another warning sign inside the panel advises to "Keep branch circuit wiring outside gutter posts and avoid crossing wires over breakers." The branch circuit wires (L1-black, L2-red, G-green, plus a white neutral wire shown heading towards the outlet, though its connection point from the neutral busbar for this specific circuit isn't explicitly drawn) are shown running towards a yellow NEMA 14-50 style electrical receptacle. Arrows indicate the direction "To EV charger (current flow)". Adjacent to the outlet is an icon representing the "40 A Level 2 EV Charger" itself, along with its charging plug. Text indicates this is a "9.6kW EV charger (240V = 40A)". A significant warning message states: "40A charger needs a 50A breaker per NEC 80% rule," explaining the use of a 50A breaker for a 40A continuous load device. The bottom of the diagram reaffirms this is for "Single Phase Panel Wiring (US-NEC)". A logo for "Electric Vehicle Geek" is in the bottom left corner.

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:A detailed diagram titled "EV Charger Wiring - 240V (4-Wire: L1, L2, Neutral, Ground) - UBIFO250N Breaker" from electricvehiclegeek.com. The diagram illustrates the wiring process for an EV charger from a 120/240V main electrical panel. Key components shown include: Power from Utility: L1 (Hot 1), L2 (Hot 2), and N (Neutral) lines entering the panel. Main Panel: Active lugs on the main breaker (noted as continuously live), the main panel breaker, an EV charger dedicated 2-pole 50A circuit breaker (Connecticut Electric UBIFO250N), neutral busbar, and ground (G) busbar. Electrical bonding between neutral and ground busbars is indicated. An earth conductor connects the ground busbar to a ground rod. EV Charger Branch Circuit: A 240V EV charger branch circuit (L1, L2, N & G) exits the panel through a 3/4" conduit. Wires are specified as 6 AWG 90C Copper Wire. Connection Options: The circuit leads to either: A NEMA 14-50 outlet for a "Plug-in EV Charger." A "Hardwired EV Charger Terminal Wiring" block, showing connections for L1 (Black), L2 (Red), N (White), and G (Green). EV Charger Example: A "40 A Level 2 EV Charger" (9.6kW, 240V=40A) is shown, with an icon of a charger plug. Important Notes: A warning that active lugs are continuously live. Advice to keep branch circuit wiring outside gutter posts and avoid crossing wires over breakers. A note on voltage drop, advising to upsize wires on long runs to keep voltage drop under 3% per NEC. A critical warning: "40A charger needs a 50A breaker per NEC 80% rule." The diagram aims to provide a visual guide for correctly and safely wiring a Level 2 EV charger.

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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.A detailed diagram titled "EV Charger Wiring - 240V (3-Wire: L1, L2, Ground) - UBIFO250N Breaker" from electricvehiclegeek.com. The diagram illustrates the wiring process for an EV charger using a 3-wire (L1, L2, Ground) 240V setup from a main electrical panel. Key components shown include: Power from Utility: L1 (Hot 1), L2 (Hot 2), and N (Neutral) lines entering the panel. Main Panel: Active lugs on the main breaker (noted as continuously live), the main panel breaker, an EV charger dedicated 2-pole 50A circuit breaker (Connecticut Electric UBIFO250N), neutral busbar, and ground (G) busbar. Electrical bonding between neutral and ground busbars is indicated. An earth conductor connects the ground busbar to a ground rod. EV Charger Branch Circuit: A 240V EV charger branch circuit (L1, L2, & G) exits the panel through a 3/4" conduit. Wires are specified as 6 AWG 90C, Copper Wire. Connection Options: The circuit leads to either: A NEMA 6-50 outlet for a "Plug-in EV Charger." A "Hardwired EV Charger Terminal Wiring" block, showing connections for L1 - LINE 1 (Black), L2 - LINE 2 (Red), and G - GROUND (Green). EV Charger Example: A "40 A Level 2 EV Charger" (9.6kW, 240V = 40A) is shown, with an icon of a charger plug. Important Notes: A warning that active lugs are continuously live. Advice to keep branch circuit wiring outside gutter posts and avoid crossing wires over breakers. A note on voltage drop, advising to upsize wires on long runs to keep voltage drop under 3% per NEC. A critical warning: "40A charger needs a 50A breaker per NEC 80% rule." The diagram aims to provide a visual guide for correctly and safely wiring a Level 2 EV charger in a 3-wire configuration.

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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:A detailed diagram titled "EV Charger Wiring - 240V (3-Wire: L1, L2, Neutral, No Ground) - UBIFO250N Breaker" from electricvehiclegeek.com. The diagram illustrates an outdated and not recommended wiring method for an EV charger using a 3-wire (L1, L2, Neutral, with no dedicated ground wire) 240V setup from a main electrical panel. Key components shown include: Power from Utility: L1 (Hot 1), L2 (Hot 2), and N (Neutral) lines entering the panel. Main Panel: Active lugs on the main breaker (noted as continuously live), the main panel breaker, an EV charger dedicated 2-pole 50A circuit breaker (Connecticut Electric UBIFO250N), neutral busbar, and ground (G) busbar. Electrical bonding between neutral and ground busbars is indicated, and the panel itself is grounded via an earth conductor to a ground rod. EV Charger Branch Circuit: A 240V EV charger branch circuit (L1, L2, & N) exits the panel through a 3/4" conduit. Wires are specified as 6 AWG 90C, Copper Wire. Crucially, this circuit lacks a dedicated ground wire. Connection Options: The circuit leads to either: A NEMA 10-50 outlet for a "Plug-in EV Charger." A "Hardwired EV Charger Terminal Wiring" block, showing connections for L1 - LINE 1 (Black), L2 - LINE 2 (Red), and N - NEUTRAL (White). EV Charger Example: A "40 A Level 2 EV Charger" (9.6kW, 240V = 40A) is shown, with an icon of a charger plug. Important Notes: A warning that active lugs are continuously live. Advice to keep branch circuit wiring outside gutter posts and avoid crossing wires over breakers. A note on voltage drop, advising to upsize wires on long runs to keep voltage drop under 3% per NEC. A critical warning: "40A charger needs a 50A breaker per NEC 80% rule." A prominent warning stating: "The configuration (L1, L2, N - no ground) is outdated and not permitted under modern NEC requirements for EV chargers. According to NEC 250.4(A)(1) and NEC 625.54, grounding is essential for all electrical installations, including EV chargers. Avoid using this setup in new installations.

9.2Expert Score
For 240V Level 2 EV charging circuits using 40A EV chargers like the Evgoer J1772, the UBIF0250N installs securely, delivers steady performance, and handles 9.60 kW EV charger loads with ease. It’s the go-to choice for upgrading older FPE Stab-Lok panels with reliable 50A breakers—ensuring code-compliant, high-load EV charging in residential settings.
Features
9
Real World Usage
9.5
Materials
9.5
Durability
9
Craftsmanship
9
Design
9
Monetary Value
9.5
Product Value
9
Brand Reputation
8.5
Expert Valuation
9.5
PROS
  • Reliable and safe for 240V 40 A Level 2 EV chargers
  • Easy installation in Federal Pacific panels
  • High-quality copper internals for excellent conductivity
  • ETL listed and NEC compliant
CONS
  • Limited to Federal Pacific panels
  • Requires careful handling during installation

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