Auto Transfer Switch

Introduction: Auto Transfer Switch

When power goes out in my home, this switch connects my

inverter to allow my sump pump to use inverted dc power automatically.


Relay k10p-11a15-120 (DPDT, 15A, 120VAC) JAMECO # 282247, $10.95

Deep plastic conduit box

Misc wire

Two male plugs

One female plug



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    14 Discussions


    Question 4 months ago

    is your sump pump connected to 5 & 6? is there anything on 7 & 8? thanks

    4 more answers

    See diagram for other connections

    5&6, sump pump
    3-7, jumper
    4-8, jumper


    7 months ago

    Where does one get the plastic block to plug in the relay ?

    1 reply

    Check with JAMECO, I got as a set

    Thank you! It was really useful to me. Its crazy how some companies sell equipment to do this simple task for 100+ usd...

    1 reply

    Glad you can use, sometime just the simple things in life are the best

    I'm not sure if Home Depot has, I got mine on line (see description in parts list)

    Hey man wondering where you got the relay from? Could I pick it up at home depot?

    Thank you for your comments, there may be a lot of options here but this works for me neither the box nor the "connectors" are water resistant. This device doesn't need to be. It should be placed above flood level.

    Nice to see you used proper water-resistant box & connectors. Instructable could use more detail and or a schematic to make it clearer. I've used this many times at remote sites for backup power switching, works great. Even if you don't have a 110vac relay you can just use an ac adaptor to match your relay voltage.