Because of the nature of events it is normal to specify a quite large generator. This is because they tend to come with enclosures that reduce the volume of the generator to a whisper (known as super silent) and they come with bigger fuel tanks that under normal conditions will last over 12 hours. In addition they also are more reliable and have a key start.

Most of these generators are between 10kva to 20kva producing around 40 amps to 80 amps which is ample for lighting and running a small disco or band. I would always insist that the caterer brings gas equipment for cooking, coffee and water boiling. Some larger electric coffee machines can draw as much as 13amps each, caution has to be used when plugging a few of these at one time as it will overload the generator or cables.

It is good practice to site the generator some way from the marquee and provide an armoured cable between the generator and catering marquee where the power can be distributed to different parts of the event. Often a purpose built board can be used sing Cee form plugs for ease of use. If you are using band or disco lights which will draw substantial amounts of power (not the average disco) I would recommend a much larger generator as the fluctuations in power demand can upset the speed controller for the generators. Which can plunge your event into darkness.

It is also worth pointing out that the majority of generator problems, in my experience, have been due to running out of fuel. This is because the customer / caterer sets up the marquee the evening before the event. Because the generator is so quiet, no one remembers to turn it off. It then lasts around 12 hours... when it runs out of fuel around lunch time the next day! Normally just before it's required.

To prevent any problems remember to switch it off overnight and detail some one to make sure it's full just before the event starts. Having spare fuel handy is a good idea, however many generators can be reluctant to start if they have been run dry.

You should also have battery backed up lights in the event of a power failure. It may also be prudent to have a backup generator so your event can continue in the event of a problem. I have also split the power between two separate sources so if one power supply fails only half the lights go out!