So, is it safe to plug a power bar in to another power bar that is connected to a power source? I don't really want to try it, as if it is unsafe, then I don't really want to try it.
Yes but only if the total power drawn is less than the rated capacity of the source and the ratings of the power bars.
So you cannot exceed the power rating of source, bar 1 or bar 2.
I thought this was worth a diagram:
I assumed 15A just as an example, respect the ratings and regulations for your locality. I also assumed all bars and source are rated at 15A...
If bar 1 is only rated at 10A then that is the limit so the bottom 3 examples will have to change so that the bar 2 uses less...
It really, really depends on the loads involved (in amps), and you shouldn't be anywhere near the nameplate rating of these power strips, because they are oh, so very cheaply made.
So if you want to plug in a bunch of wall-warts and cell phone chargers and maybe a PC, that is fine. However if you have any sort of high-current (high heat making) appliance like a big gaming PC, laser printer, air conditioner, floor heater, you name it, then you should definitely avoid it unless you are using a very high quality strip like Tripp-Lite. For those appliances, run a quality extension cord straight from the receptacle. (you can't have 2+ of them on a circuit anyway).
No, it is not. This violates safety regulations.
These devices are only approved to provide power to a specific number of electrical appliances, and daisy chaining them increases that number and creates a potential fire risk. Additionally, you shouldn't daisy chain them with extension cords, either, because that is also a risk.
Here is the real scoop. Effectively, when you daisy chain anything that has a fuse included to protect the device, you SHOULD NEVER connect one to another. This goes for protected extension cords as well. The reason for this is complicated and you will read a ton of crap online that will justify and explain why you can do this. The answer simply comes down to the current interrupting capability when they are both in series and the voltage drop involved with respect to the value of each resistor. I did this twice and both times the downstream power stripe was destroyed. I sought the reason why and it comes down to Equivalent resistance, voltage drops and current interrupting capabilities when they are combined. Think Ohms law. DON'T do it unless you want a fire in your home.