Generator Interlock - Square "D" QO Load Center

thingiverse

This is an interlock I designed after seeing a similar layout for a GE load center but couldn't find one for my particular load center. This design will not allow the generator to be on at the same time as the main circuit breaker thus preventing back feeding the main lines to the power company and endangering lineman. Note - this is for panels with a 4" gap between main breaker and the other cluster of breakers. I did eventually find one pre-made selling for $70+ on Amazon. It indicates it can work on 3 1/4" to 4" gaps. If yours is 3 1/4" you put the breaker on the left side of the box which moves the switch lower allowing the 4" design gap to work. If you mirror my design I believe this would work for you too (not confirmed) I printed the pictured version in PLA but plan to reprint in PETG for longevity. I used the following hardware so it can slide back and forth. Spacer: #6 ID X 1/4 in. OD X 1/4 in. L, Aluminum https://www.amazon.com/dp/B07DS92CBH/ref=cm_sw_em_r_mt_dp_U_fNJ5EbXHTXWBZ Bolt: M6x32 https://www.amazon.com/dp/B07Q3MHL9Q/ref=cm_sw_em_r_mt_dp_U_DOJ5EbQ8P1KZX Locking Nut: 6-32 304 Stainless Steel Nylon Inserted Lock Nut, 18-8 Nylock https://www.amazon.com/dp/B07Z8PDX6S/ref=cm_sw_em_r_mt_dp_U_7PJ5EbB5WEK40 I used some washers I had on hand already. I needed space between the interlock and the panel so it fit over the breaker edges. The designs I see forsale have a whole second plate behind the for this purpose. I decided to space out the bolt. I went in this order: Bolt + washer + spacer + interlock + washer + nylon nut + panel + Nylon nut. It worked perfectly with no play and I believe using the nylon nuts should keep it that way.