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What is a Sub Feed Breaker? (Definition, Purposes & More)

Written by Edwin Jones / Fact checked by Andrew Wright

what is a sub feed breaker

A sub feed breaker is significantly useful, especially when the main service panel is not enough for the circuit installation. This might happen when you want to add a higher-rated appliance but the available branch breakers cannot protect it.

Therefore, using a sub feed breaker, you can make a secondary load center to safeguard your electronics. If you want a further understanding of what is a sub feed breaker, you should read this article from beginning to end.

What is A Sub Feed Panel Breaker?



A sub feed breaker is a breaker placed inside the main service panel for a sub panel connection. Normally, it is located at the bottom end of the main panel board, connected using a sub feed wire set, tapping screws, and extension rails.

Its amperage rating is normally high, reaching up to 225 amps 0r even 400 amps. Moreover, its physical size is also larger than regular circuit breakers. As a result, it can extend the panel box’s height.


A sub feed breaker is used when an appliance load exceeds the capacity of interior breakers. It is mounted opposite the panel mains and is much bigger than regular overcurrent protectors.

Frequently Asked Questions


Do I Need a Breaker to Feed a Sub-Panel?

Yes! Usually, a sub-panel requires a branch breaker located at the main service panel. In most cases, a circuit breaker subpanel will use a 60-amp breaker, though sizing will vary. In any case, the rating of this device should be enough to feed the sub-panel.

What is the Difference Between Sub Feed Vs Feed Thru Lugs?

Both applications can add a new panel or circuit for a specific device. They are also both protected by the main breaker of the service panel. However, they have differences in where they are installed.

Sub feed lugs are primarily put in the upper part of the panel board, while the feed thru lugs is installed at the bottom part.

How much is a 200 amp feed through lugs?

The feed-thru lug kit with a rating of 3 amps can be as affordable as $13 if you want a replacement. However, if you want the 200-amp main breaker load center, it can cost you from $130 to over $200.

Sub-feed lug replacement

Sub feed lug connections are often located at the top of the panel board. You can replace the main lugs with a larger size by using Square D sub feed lugs or other brands.

Depending on the sort of feed breaker kit you select, a sub feed lug block may be required. This device connector is useful for connecting a secondary panel board connection using the panel’s brancmeh circuit.

Some of these devices usually come at two poles and three poles. At the same time, there are sub feed lug kits, such as the Siemens sub feed lug kit and HOML2225 sub feed lug kit, that accommodate at least four single pole circuit spaces.

How does a feed through breaker panel work?

The incoming total current will go through the panel’s main lug as brand breaker load currents and through the feed-thru lug as downstream load current.


If you have a building with a large service panel, it is a good idea to understand what is a sub feed breaker. By utilizing a secondary distribution box, you may be able to reduce the cost of electrical wiring. This way, instead of large long conductors connected to the main panel service, you only need small and short conductors.

Remember that a sub feed breaker should also satisfy NEC codes, and installing it is not suitable for beginners. As a result, hiring a qualified professional is the best option if you intend to have this electrical installation done.

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