Monitoring power usage

[keymoo]

My APC ES 700 UPS keeps beeping but I don't know why. I'm wondering if I'm overloading it and I'm also curious to know how much power my various devices consume. I'm thinking of buying a power monitor, but not sure which one. Has anyone bought one?

I notice a lot of them require the device you are monitoring to plug into the unit itself, like this one [REMOVED]

I would prefer a unit where you can clip onto the cable and monitor so I don't have to power cycle the monitored device. Does such a thing exist?

 

[keymoo]

Had a look at a few via Google but they all seem to measure current and voltage but don't give an easy power reading. Do you know of any that do that?

 

[keymoo]

Two ADSL routers, a home server, two switches, one wireless access point, cordless phone.