My daughter is going to the US to study for 4 months and needs to take her laptop (HP Pavilion). The only travel adaptor I can find states, "do not use with earthed appliances, only use with Class II equipment, ie appliances connected through two-core mains supply cable".
The adaptor supplied with the laptop states "connect to grounded outlet" and the power source cable connects to the adaptor via a 3 pronged connection. I assume therefore that this cannot be used with the travel adaptor. We are therefore a bit stuck, seeing as she is going on Friday!
You will almost certainly find that on the power unit the label says that it is suitable for 100 to 240 Volts and so is suitable for US mains. I think the "earthed appliances" warning is simply telling you that the earth lead doesn't connect through to the computer, and so the power unit shouldn't be used for an appliance that requires earthing.
Don't worry. I travelled to the USA almost monthly for years with my UK laptop and power supply and travel adaptor, with no problems. The laptop power supply output (19 volts or so) is SELV (safety extra low voltage) and doesn't rely on the earth connection for its integrity.
Hi thank you for your responses. I'm okay about the voltage it's just the "earthing", My old laptop just has a two pronged connector to the laptop adaptor but my daughter's has a three pronged connector so I'm assuming this is earthed, and with the travel adaptor saying "do not use with earthed appliances" it's got me worried.
In fact I'll be there in ten days time, and the power charger works perfectly via one of those universal adapters on which you rotate a face plate to the appropriate country. I bought my mine in Dixons at Heathrow several years ago, and it works all over the world.
Your laptop is designed to travel, it will be fine.