Quoted from YeOldPinPlayer:
I'd ask an electrician how to test current draw for a set period of time (hours). Seems like a Fluke 376 might do it, record results to a smartphone. amazon.com link »
At $400 it's more than I'd pay for just testing but an electrician might have a good solution on hand.
I don't know what this would do (testing over time_) unless you were concerned with your power bill.
Safety etc. will be dictated by the load on the wires (and breakers) over a short period of time as they heat up and bad things happen.
Something like a TED http://www.theenergydetective.com/ would give you a history of usage. so would a kill-a-watt meter amazon.com link »
(I believe they do usage over time) or a few of them with all your pins plugged into them and you could add up the results.