Nose cargo and main side doors. Wondering why?

[Nixon 30]

Hi

Am intrigued to know why Boeing designed the freighter nose and side doors to require one power source to be available but not used whilst the other power source is connected?

 

Is it for safety reasons? Thinking of safety am also wondering if in the real world there is any sort of protection to stop the nose door being closed accidentally?

 

I have tried an Internet search but couldn't find the answer. If anyone knows I would be grateful.

[Captain Kevin 586]

Whether this is a fact, I don't know, but some form of explanation was posted here.

 

http://www.avsim.com/topic/503102-can´t-open-any-maindeck-cargo-door/

[Nixon 30]

Thanks Captain Kevin

I used the phrase "nose cargo door" and not "main cargo door". Having read that thread I now have a better understanding of the reasons behind using only one power source.