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Circuit Breaker Termination


A terminal is the component used to electrically connect the circuit breaker to the circuit it's protecting. For example: a wire, with or without a connector at its end, can be attached to the circuit breaker through the terminal.

Carling Technologies offers a wide variety of terminals. The proper choice of termination is largely dependent on the current rating of the breaker, regulatory agency requirements, wire gauge and connectors. A key question to ask yourself when selecting a circuit breaker is: Are the wires, connectors and terminations rated to handle the maximum current rating?

Form & Fit Dimensions Available

Downloadable PDF files which contain the form and fit drawings for the terminations listed below, along with other dimensional and electrical specifications, can be found on the specific series' product page within this web site.

Quick Connect Tabs Terminals

Carling offers .250 inch quick connect tab terminals that are designed to fit securely into a comparable female quick connector. This "push-on" connection is made without the need for external hardware such as hex nuts or screws, making for "quick" installation.

The quick connect tab terminal is rated up to 30 amps. However certain regulatory agencies, such as VDE, require screw termination for ratings greater than 25 amps. Therefore, Carling Technologies typically recommends that the use of tab termination be limited to current ratings of 25 amps or less.

Quick connect tabs can also be referred to as faston, spade, tab, or QC terminals.

Carling M-Series, A-Series, B-Series, and C-Series circuit breakers offer quick connect termination.

Screw Terminals

Screw terminations are designed to affix the connecting wires, fork or ring connectors, or bus bar to the circuit breaker by tightened screws.

Generally, the screw terminal is composed of a terminal with a threaded hole and an 8-32 or 10-32 screw. Screw terminals are typically available in two styles: Bus Type or with Upturned Lugs. Bus type screw terminals are designed to make a completely flush connection with the bus bar, should bus bar be your chosen conductor. The terminal is oriented so that a vertically mounted breaker would connect to a horizontally mounted bus bar. Screw terminals with upturned lugs have the corners of the bus terminal bent slightly upward. This bend offers a more secured connection for fork or ring connectors. In some cases, the bus terminal component can also be bent at a 30-degree angle.

Carling M-Series, A-Series, and B-Series breakers offer 8-32 screw terminals.

Carling A-Series, B-Series, C-Series and E-Series breakers offer 10-32 screw terminals.

The Carling C-Series screw terminal is supplied with a 10-32 screw, a flat washer and saddle clamp. The saddle clamp is for direct wire connection, and can be discarded if a wire terminal lug is used.

The Carling D-Series breaker provides a captured #10 screw & pressure plate termination for direct wire or fork terminal connections.

8-32 screw terminals are rated up to 30 amps; 10-32 screw terminals are rated up to 50 amps. Carling E-Series circuit breakers also offer 1/4-20 screw terminals, which are rated to a maximum of 100 amps. And F-Series breakers offer 3/8-16 screw terminals rated up to 700 amps.

Metric screw terminals are also available on Carling A-Series, B-Series, and C-Series circuit breakers.

Threaded Stud Terminals

Threaded stud terminals are designed to affix connecting wires, fork or rings connectors to the circuit breaker by tightened hex nuts that fit a stud terminal. For each threaded stud terminal, Carling Technologies supplies two hex nuts and two flat washers. Designed for higher amperage ratings, these terminals are considered the most reliable and sturdy form of connection.

Carling C-Series and E-Series circuit breakers offer 10-32 and 1/4-20 threaded stud terminals. C-Series breakers also offer M5 and M6 threaded stud terminals. Carling's F-Series circuit breakers offer 3/8-16 threaded stud terminals.

10-32 and M5 stud terminals are rated up to 50 amps. 1/4-20 and M6 stud terminals are rated up to 100 amps. 3/8-16 stud terminals are rated up to 250 amps.

Box Wire Connector Terminals

Box wire connector terminals are high amperage connectors consisting of a box lug and screw. These terminals are designed for direct wire connections.

Carling Technologies' E-Series circuit breakers offer front-connected box wire connectors with or without pressure plates. The box wire connector with pressure plate accepts #14 through 0 AWG copper wire or #12 through 0 AWG aluminum wire. The box wire connector with pressure plate is designed for stranded wire. Though a more costly option, box wire connectors with pressure plates offer the most secure connection. E-Series box wire connectors are rated up to 100 amps.

Carling F-Series circuit breakers offer a front-connected box wire connector with pressure plate. In this case the box lug accepts wire size #6 to 250 MCM. F-Series box wire connectors are rated up to 700 amps.

Printed Circuit Board Terminals

Printed circuit board terminals (PC terminals) are soldered directly to a printed circuit board. Eliminating the need for wiring, these terminals provide a quick, space saving, cost effective choice, especially in those applications where multiple circuit breakers are required.

Carling Technologies offers a right-angled, back-connected PC terminal on its A-Series and B-Series circuit breakers. These terminals are rated up to 30 amps for European approval, and up to 50 amps for UL/CSA approval.

Push-In Stud Terminals

Push-in stud terminals are "bullet-shaped" terminals that fit into a .311 inch diameter mounting holes within a bus bar. A cost effective, space saving choice, the push-in stud is rapidly becoming the termination of choice for multi-pole telecommunication and power distribution applications. Push-in studs are also referred to as "bullet terminals" or "plug-in studs."

Carling's C-Series circuit breakers offer push-in stud terminals rated up to 100 amps.

Other Terminal Options

Carling A-Series and B-Series circuit breakers also offers a combination .250 quick connect tab/solder lug termination. The C-Series circuit breaker offers 1/4 fuse clip and 7/16 fuse clip terminals designed to fit on rounded bus rods.

For special termination needs, please contact your Carling Technologies Sales Representative.

Auxiliary Switch Termination

There are also a variety of termination choices for the auxiliary switch that may be a part of your circuit breaker configuration:

  • M-Series circuit breakers offer .060 inch diameter double solder turrets or .058 inch diameter round quick connect terminals.
  • The Carling A-Series and B-Series circuit breakers offer .110 inch quick connect terminals and .139 inch solder lugs. The A Series circuit breaker also offers a .093 inch quick connect terminal.
  • Carling's C-Series circuit breakers offer .110 inch and .187 inch quick connect tabs. They also offer the .139 inch solder lug termination.
  • Carling's F-Series circuit breakers offer .110 inch quick connects, .139 inch solder lugs, and .093 diameter round quick connect terminations.