Mechanical Interlock For Two Incomers

If the two MCCBs are side-by-side, you can mount a slider bar above the two handles so if you slide the bar to the left, you can operate the right CB, and vice versa.

That's why Castell Key (usual disclaimer) mechanical interlocks have been used for this application, and many others, for several decades.

switch fuse units with mechanical interlocking are easily availabe in the market, you can use the same instead of mccb's. These mechanical interlocking is provided with a single key,the advantage is that you can not remove the key from one switch untill you switch off the other.

If, as Tornado said, your MCCBs are very close as to allow a mechanical bar to slide over the handles, then you could rig out this. Otherwise, and even if close by, there are systems in the market that provide a captive key device to install on the MCCBs handles (CASTEL and others) in such a way that you need to insert a key before operating the switch to ON and the key will be trapped in and will only come out if the switch is turned to OFF. The same key should be used for both MCCBs.

Finding the Key devices: Most reputable makers of MCCBs do provide such systems either straight from their catalogue listings or on enquiry. They can adapt the devices from third a party to suit their MCCBs.

To avoid accidental paralleling the second source castel key interlock can be provided.If we open the first incomer and remove the castel key and put in the second incomer then only it will allow to close the incomer2.