1800 watts is roughly 15 amps. I have a kilowatt that ive used for several years on my electric still. After a while if you are pulling heavy current through it it will start to melt around the plug on the unit. The clips inside get spread apart / loose after a while and it doesn't make a super good connection and can heat up. The unit is rated at 1800/1875 watts depending on the model you have but it will handle small surges. I had one that my microwave would push around 2050 watts for about the first 45 seconds until it started stepping down to the power to the magnetron.
They are nice little units though, however one other drawback, as soon as you remove power, your data goes away, ie it doesn't store you kw history for example. They do have a model, or did have a model that did that for you but I haven't found it recently.
You can get good deals on these things brand new from e bay too.
Aaron