Here is the link to the emergency stop switch - http://www.ebay.com/itm/NC-N-C-Emergency-Stop-Switch-Push-Button-Mushroom-Push-Button-4Screw-Terminal-K2-/272048010923?hash=item3f575336ab. Thanks.
The switch is rated for 10A. 4500W @ 220V is about 20.5A, double the maximum rated current.
The purpose of this switch is to turn on/off the safety relay. If you do not intend to use safety relay, than use at least a normal contactor/relay.