Sub-second power outages only on some circuits

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How long is a piece of string? 
it could last years or could fail tomorrow. What is for sure the longer you leave it the worse your problems will become. 


pretty much this. longe rits left the more damage that will be done. what could simply be a case of tightening a screw now could be replacing MCB's / isolators, cutting out and replacing damaged cables etc later on once its burnt out. or worse and needing a new building after its burnt down

 
The looser a screw at a connection the higher the resistance to current flowing through it. It gets hot, potentially real hot. A thermal image survey might show this hot spot(s). I know there's often resistance (no pun intended) from tenants to shutting down power for testing purposes due to downtime and cost but some nice images with hot spots can be shown as fair warning things are likely to get worse rather than better. If you're not having periodic inspections you might even invalidate your buildings insurance. 

 
UPDATE:

Hi Everyone

An electrician has just come round to have a look and found no problems and everything is tight.

I now suspect that the answer is as follows:

It may actually be the case that the fault is outside the building after all and what I experienced last Friday may be explained as follows:

Firstly, in my original post on this thread, I mentioned that the lights do not go off when this problem happens. This was based on my last experience of the problem which was last Friday. I suspect that it might be the case that I blinked at the precise time the power went off and on so I did not see the lights going off and on.

It may be the case that most of the computers in the building have enough capacitance in their inbuilt Power Supply Units to keep them going without rebooting or shutting down when the power goes out for only a few milliseconds but the server and the other computer on the same circuit do not have enough capacitance to do this. (There are no other computers in the building of the same models as the ones affected by the problem.)

Is the above a possible explanation?

 
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