I just began renting an apartment in a c1900 house. In one month, the power on a single circuit has bound out for exactly one second, four times now. Of course it is the (20amp) circuit that I have my router, a desktop computer, a laptop, a 24in flat screen TV, a Roku, Apple TV, a cordless phone, and a single lamp burning one 100W bulb plugged in to.


It wreaks havoc on my poor desktop system, not to mention all my wireless electronics, and pretty much everything takes five minutes just to boot back up.


What is the most likely culprit?

Circa 1900 doesn't tell us a lot. A home from the mid 60's through mid 70's might have Aluminum wiring instead of Copper. This opens the door to a myriad of wiring problems. The most likely villain is a loose connection that gets hot and opens.

Have your landlord get a electrician out to check the circuit.

As don says for permanent fix. But, reducing the load on that circuit might help in the interim (if you can do so without creating extension cord hazards), as well as using the laptop (with its own battery backup, but you will still lose the router) and/or purchase a battery backup system for the desktop components and router (but number of actual backed up receptacles on backup unit will be limited). If you could just plug the router into another non-affected circuit and use the laptop for critical internet operations would also help til the problem is found. Moving the router should not be too difficult, especially if you are using wi-fi.
Are you certain it is just the one circuit and have you asked any of your fellow tenants if they are experiencing the problem? The exact time outage sounds like power company "blips" but they don't normally affect just a portion of your service. If other tenants are experiencing the same problem, the problem could be just about anywhere in the building or a power company issue.
You can expect the landlord and/or the electrician to question the number of devices operating on that one 20A circuit but that really doesn't explain the problem in itself, if the breaker or fuse doesn't have to be reset or replaced when the outage occurs. Backstabbed outlets (instead of conductors attached to receptacle screws) are a possibility too but you need some expertise to check that out.
The only one most likely culprit (that you have any control over) in my opinion, is the large load on that circuit. Reducing it is worth a try but a hazardous condition may be in existence in your apartment or elsewhere in the building, even if splitting up the loads, works for your immediate problem.

How do you know it's just that one circuit? Obviously you know the problem exists because you have so many reliant devices on it, but that doesn't mean it's not the entire home. You really don't have much of a load on that circuit. What is the frequency of these "cut-outs"? How many circuits do you have in your home?
Is it daily, weekly, hourly, once in a while or what? The battery backup will take care of the computer issues, but won't solve the problem. Does your landord know about this... and what does he have to say?