Although the power supply in Cuba is mainly 110 volts, most of the modern hotels have dual voltage with all the sockets in the room being 220 volts.     Usually in the bathroom there is an 110 volt socket suitable for shavers and charging batteries.   A 4 gang 13 amp extension lead could well prove very useful,    All UK appliances will work in Cuba and all you will need is an adapter.     Wilkinsons (Wilko's) sell two adapters in one pack (1 euro rounded two pin and one North American flat pin) costing £3.75 as at June 2015.   The type of adapters necessary for UK travellers are shown below.

 

 

The sockets in the rooms are cleverly designed so they will take the North American flat 2 pin and the European rounded two pin plugs and are usually similar to these, the bottom one being the one in the bathroom.

.                                                    

Unless their appliances are dual voltage, Canadian guests will need a voltage converter to reduce the voltage down from 220 volts to 110 volts and need to be very careful, as most of their appliances will plug into the sockets OK, but the difference in voltage will 'fry' the appliance.   

The 110 volt socket in the bathroom is only suitable for low wattage items like shavers and battery chargers and is not suitable for 'high draw' appliances that generate heat.  Note recently there have been some resorts changing their hairdryers in the rooms and the housing no longer have this 110 volt "shaver outlet" located in the base.

Most digital camera and camcorder battery chargers these days will work on both voltages, as will laptop computers.  Check your charger and if it says: Input: AC 110V-240V~50Hz/60Hz it will be OK to plug into the 220 volt socket.

Some Canadian appliances such as hairdryers, curling irons and straighteners (flat irons), even though they may be dual voltage, the plug on the appliance may be polarised (ie: one pin is wider than the other).   If that is the case then an adapter will be required, similar to that shown below.  In the first photo the hole on the left is larger and that is where the polarized pin of the appliance should be plugged into. Canadians may also use a power bar that has its "ground" pin removed.  Cuban wall sockets aren't well grounded and simply pulling the ground pin out works best.