Utility - Generator Panel InterLock

Introduction: Utility - Generator Panel InterLock

This is a 3D printed version of the Square D Interlock. It allows you to use a generator to power your home during utility power outages restricting the power supplied to the circuit panel to a single source -- Utility Power OR Generator Power..

This interlock is designed for a Square D breaker panel but could be modified to work on most circuit breaker panels. The concept is simple: The main breaker must be switched OFF so the Auxiliary breaker that is connected to the Backup Power (generator) can be switched ON. This interlock prevents more than one of these sources to be ON, or powering the circuit panel, at any time.

NOTE: This Instructable is limited to fabricating the actual interlock. Please refer to other Instructables for the actual wiring requirements.

Basic usage: when you lose utility power (once wired properly):

1. Attach the generator.
2. Start the generator.
3. Switch the Main Breaker OFF.
4. Slide the interlock UP.
5. Switch the Aux breaker ON.

Your home is now powered by the generator.

Supplies

3D printed Interlock.
3 each 4-40 taper head screws with t-nuts

Step 1: Print the Interlock

Included are both the Sketchup18 source file and the STL file for the Square D panel.
You can modify the Sketchup file to fit your circuit panel and recreate the STL.
This interlock is printed with ABS.

Step 2: Mounting the Interlock on the Panel

You might want to consider electrician to perform or assist with the following:

1. Carefully remove the safety panel shield cover from the circuit panel. Usually, 6 exposed screws. Be very careful around the exposed live panel.

2. Drill and taper the backside of the shield panel with 3 holes using the printed interlock as a guide.

3. Secure the interlock to the front of the shield panel using 3 4-40 screws and t-locks. Make sure it slides up and down freely. Slide it to the down position.

4. Switch AUX breaker OFF.

5. Re-install the safety front panel with the interlock DOWN and the MAIN breaker ON. (AUX OFF).

See INTRO for operating instructions, repeated below.

So when you lose utility power:
1. Plug the generator (or aux) into the L5-30r plug.
2. Start the generator.
3. Switch the Main Breaker OFF.
4. Slide the interlock UP and
5. Switch the Aux breaker ON.

Your home is now powered by the generator.

Step 3:

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    3 Comments

    0
    Penolopy Bulnick
    Penolopy Bulnick

    1 year ago

    Nice idea!

    You should consider entering the 3D Printed Contest :)

    0
    RobertD171
    RobertD171

    Reply 1 year ago

    Thank you. Would appreciate your vote too.

    0
    NeilRG
    NeilRG

    1 year ago

    I am voting for this entry. During power outages, some people make a double male plug to run from the generator outlet to a wall outlet in the house. One major problem is that the power transformers that step the voltage down going into the home will also step the voltage up when there is a power outage, which puts the utility company workers in danger of electrocution from this backfeed.
    The other issues are generator damage when the power is restored, and the idea that outlet wiring is undersized for this purpose
    I have not read the wiring instructable you reference because my panel was upgraded several years ago and incorporates this feature, so my comments might be redundant.