1. 
   MCB
   abbreviation: Marine Corps Base
   Found op http://www.apscharts.com/abbrev.html
   
   
2. 
   MCB
   Memory Control Block
   Found op http://www.encyclo.co.uk/visitor-contributions.php
   
   
3. 
   MCB
   Miniature Circuit Breaker - Modern replacement for fuses in consumer units (fuse boxes). Has benefit of more precise tripping and can be reset. In my opinion all fuse boxes and consumer units that still have fuses should be converted to use these.
   Found op http://basic1.easily.co.uk/039069/01C053/electrical_glossary.htm
   
   
4. 
   MCB
   Molecular and Cellular Biology [periodical, périodique]
   Found op http://www.encyclo.co.uk/local/20895
   
   
5. 
   MCB
   Miniature circuit breaker, these are the switches (or fuses) protecting each circuit.
   Found op http://www.encyclo.co.uk/local/21604
   
   
6. 
   mcb
   1) Abbreviation
   Found op marine corps base
   
   

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