Does each phase of my three phase have 60 amps?
If I draw more than 60 amps on a phase will it trip the switch?
How can I work out if I am pulling more power than I have, is it a simple case of adding up all the amps my appliances are using at once?

You need to provide some details of your electrical system before anyone here can provide answers to your vague questions.

OK could you tell me what people would need to know. I'm a snowed in and would like to sort the problem or at least understand it a bit more so I can stop it happening until I can get some one here to have a look. All I know is that my electricity keeps going off when I plug an appliance in, but not always the same appliance. The three phases are split across my three buildings. Each building has its own fuse board. None of these fuse board switches are tripping its only ever the main switch in the main fuse board where the mains enters the building. It has been very cold here recently down to -17 C at the lowest. If you could steer me in the right direction of what I should be asking I would appriciate it very much.