If the first power strip has a circuit breaker, then everything downstream of that strip is limited to the current available on that single power strip. It dosen't matter how many strips are plugged together, the current limitation will stay the same, unless there are smaller circuit breakers downstream, in which case the limitation will decrease at that point.
I do note your concern about overloading, and I will note that it's not so much that the circuit will be overloaded, as it is that the single outlet on either the first power strip, or the wall may become overloaded.
What matters most is the condition of the wiring, including the power strips, and it is for that reason that I suggest using quality power strips, from a known vendor, and avoiding the generic plastic strips made in the third world.
Keep your power strips in good condition, and dispose of them when they show signs of abuse or wear. Strips that have broken ground pins should be disposed of, or have the plugs replaced.
Large loads such as laser printers or copiers, should be plugged into wall circuits if at all possible.
Wall outlets that are worn, or otherwise abused, should be replaced by a electrician, or other qualified person.
I prefer not to daisy chain strips together, but instead pick a high quality strip to be the master, and use that to feed the other strips, thus distributing the load across multiple outlets on the power strip.
It would also be a good idea to mount your power strips to a board, desk, wall, or other fixed object to keep the wiring from becoming a tangled mess.
Try to keep your wall warts separated enough so that cooling does not become a problem. Do not pile stuff on top of power strips. Do not let wall warts get buried in the carpet.
Your typical wall wart is going to draw between .1amp and 2amps, although some may draw more, check the nameplate rating.
A quick sampling of the wall warts in my office comes up with the following: radio charger 24w(0.2amp), ethernet switch 18w(0.15amp), cellphone charger 6w(0.05amp), wireless bridge 30w(0.25amp), dsl bridge 18w(0.15amp), Palm charger 18w(0.15amp), etc ... Total load of the 6 wall warts in this example = 108w = 0.9a
A generic power strip is normally protected with a 15amp circuit breaker. Since many of the power strips available today are cheap plastic junk, I would advise that those be derated even further, to no more than 10amps.
Your normal wall circuit is going to be either 15 or 20amps.
A circuit should not be loaded to more than 80% of it's rated capacity under normal usage, which says that the maximum load on a 15amp power strip should be no more than 12 amps, assuming that nothing else is plugged into the same circuit. In a house, there may be 1-12 (or more) outlets on a single circuit depending on when the home was built, how cheap the builder was, and if the homeowner/handyman/etc has added outlets without proper capacity planning.
P(watts) = I(current)*E(voltage), so:
2400w @120v = 20a 1800w @120v = 15a 1440w @120v = 12a 1200w @120v = 10a 600w @120v = 5a 120w @120v = 1a 12w @120v = 0.1aAs you can see, it takes a lot of your typical wall warts to overload a normal household circuit, or even a cheap generic power strip.
-- Welcome My Son, Welcome To The Machine -- Bob Vaughan | techie @ tantivy.net | | P.O. Box 19792, Stanford, Ca 94309 |
-- I am Me, I am only Me, And no one else is Me, What could be simpler? --
[TELECOM Digest Editor's Note: I changed my setup today to use the three outlets on the back of a UPS to connect the three power strips each separately. Then I used the two newly gained outlets on the power strips (where strip 2 was fed from 1 and where strip 3 was fed from strip 2) to plug in the two devices which lost their home when the plugs on the back of the UPS were taken over. It seems to have balanced the load a little better. PAT]