While you may know how to install a new or existing appliance, hiring a professional is still a better option. Doing it on your own, you may be able to save some money, but, it may bring you some long-term consequences, which would be more expensive to deal with.
Moreover, a DIY install is not professionally supervised and hence, may put you, your property and people occupying it at risk. Hence, no matter small or big, you must hire an expert and professional electrician for all type of installation jobs.