My experience with an MCB Interlock device has been a total success so far.

I needed to build a control box for my solar well. My solar well pump can directly accept AC or DC power. Part of the box build included an AC inlet for my genset and the incoming DC power from the PV array. I needed to make it easy to switch between power sources quickly and safely. And ensure that power could not come from both sources at once. Although highly unlikely that would ever be attempted, I wanted to ensure it as an impossibility. Hence, the “interlock” concept.

I first heard about their existence here on the forum, I don’t remember which thread. I purchased an interlock device off Amazon along with two Mollum MCBs; 20aAC and 25aDC. They arrived, and it didn’t work.

Problem: Mollum MCBs are not compatible with the interlock I purchased. Mollum breakers have the flip lever in the vertical middle of the unit. The interlock won’t slide with that configuration. So I purchased two Chtaixi MCBs after doing a bit of research (i.e. opening my eyes); its flip lever is located towards the bottom of the unit.

I Slid everything onto a DIN rail and it worked just as advertised.

So let me show you how it looks in my control box build…

AC power…

DC power…

But, here is a cool feature that I just stumbled upon…

Yup, when you want to lock out all incoming power from the genset or the PV array it turns into a “lock out”. Yeah, yeah…I know there is no place for a true padlock or even a tag to prevent sliding the interlock into operational capability. But, for me it is just a cool feature for added safety…not ultimate safety.

So, for a total of $48 I have the circuit breakers I need to disconnect power and protect the wire AND I have a device to safely and easily switch between power sources. Not a bad deal in my book.

If this is something that interests you…

The interlock: https://amzn.to/43JeNWI

AC MCB circuit breaker: https://amzn.to/3K7z29S

DC MCB circuit breaker: https://amzn.to/3Ko7xZH