I have a USB-Mains power adapter for charging up an iPod, which I thought I would use to power my Pi.
It looks like this: with USB one side, and Mains the other.
I was wondering if there are any dangers I need to be aware of when connecting my Pi to an adapter like this? I assume it is fused and everything, but better safe than sorry.
Just realising I may be answering my own question, but it has 1A, 5V output.
Looks perfect to me (1000mA, 5V DC output). The point is that you are not connecting directly to the mains. The plug contains a transformer which converts the high-voltage AC input to low voltage DC output suitable as a USB power source. Directly connecting to the mains would be very dangerous!
Many phone chargers use the same sort of plug - I have Apple and HTC chargers that work on this basis.
It would seem that, as long as the ratings are correct (which they appear to be on your model) doing this should be just fine.
After all people trust $500 smartphones to these plugs, so a $35 RPi is a much less risky proposition.
There are dangers, and I don't see how they could be explained any better than by this blog post
To summarise:
The danger of this kind of adapters is their size. Main's electricity is in very close proximity to the low voltage output. It is perfectly possible to make these items safe, and there are official standards such as the CE mark that enforce minimum gaps and methods of designs that make these adapters perfectly safe. The problem is that not every manufacturer follows these guidelines, and some even claim to do so when they do not. You do not have to look far to find examples of products that fail unexpectedly, and it is possible for a failure to cause a fire.
Dangerous design could occur in any electronic device, but these devices are more prone to it because they are so small. I use them myself, but I ensure I get them from suppliers I consider reputable, and pay a bit more for them.
The answer IMHO is both yes and no. Yes, it is possible, but I would be careful about it. If you decide to do so, I would highly recommend using a power strip with surge protector. This way, you can protect your precious RasPi for any surge on the main supply that may go through your USB power unit and damage your device.
Here you have some good info about the surge protection: http://en.wikipedia.org/wiki/Surge_protector http://electronics.howstuffworks.com/everyday-tech/surge-protector.htm
I think the link David provided is also very useful and valuable.
not every manufacturer follows these guidelines
Assuming the charger is from Apple (which seems the most reasonable guess since it's an iPod charger), is it realistic to fear the charger is not well produced? Apple is usually criticized for design choices, not for manufacturing quality (which is usually excellent), even after excluding fanboys.
– Blaisorblade Jan 12 '13 at 18:20