Background: I recently put in a new circuit to stop blowing the breaker on a line that shared my washer, dryer, and dishwasher. Hurrah! So, I got to thinking...

Question: I have a LOT of computer gadgets plugged into a circuit, but I never seem to have any problem with it. However, when I add up all the input amps for gadget chargers, computers, etc, I wonder why am I NOT blowing a circuit breaker?

Example (assuming my math is correct):

12 Amps for desktop computer #1
10 Amps for desktop computer #2
(hmm, should have blown a 20 amp circuit already?)
3 Amps for 6x60w light bulbs
2.5 A for an HP Laptop charger
1.3 A for a Dell Laptop charger
1.5 A for an external Monitor#1
1.0 A for an external Monitor#2
2 A for printer #1
.5 A for printer #2
.75 A for my air purifier
.35 A for a portable phone
.2 A for my cell phone charger
.08 A for my digital camera charger

That doesn't even include the TV, papper shredder, various external USB drives that I often plug in, etc.

Yes, all this stuff is on the same 20-amp circuit breaker. What am I missing here? Do the computers not really draw the power listed on the power supplies? If that's the case, how do I really calculate my needs? I have new gadgets to plug in, but I'm concerned.

They are all MAXIMUMS. Think of a car, say 400 HP. At idle, your using 0 HP. What about going downhill? Pulling on a tree? Coasting? Steady state speed?

All different power levels.

Cell phone charger: Batter fully charged. Batter fully discharged. Battery, somewhere in between. All different power levels.

A cheap device such as this would help: Amazon.com: P3 International P4400 Kill A Watt Electricity Usage Monitor: Camera & Photo

Some devices, still relatively cheap have graphing capabilities and the abilit to download to a computer.

You should limit the circuit loading to 80% if the loads are on all the time.

We don't get notificatons when reputation is given. We have to look.

Looking at your list again, the laptop chargers and the computer power draw is very variable and probably no where near the listed currents.

The light bubs can be counted directly and probably the air purifier too. The monitors are probably close to the rated power. That would depend primarily on brightness. Printers aren't on all the time.

The phone may only draw that amount of current if the battery is nearly dead and the phone rings.

Get the idea?