I am having the kitchen renovated.

Part of this is an integrated fridge and integrated freezer i.e. the appliance doors are screwed to the kitchen doors.

At my insistence, the power outlets are above the appliances but in cupboards above the fridge and freezer.

There is a chance that if I take out either plugs for the appliances, I could drop one of both of the plugs and that would mean the appliance(s) would have to be removed to reach the plug(s) and then re-installed.

What can I do to ensure the plugs cannot slip down the holes?

I am reminded of office desks which have a hole for the plugs to fit through and then a plastic cap to ensure the plugs cannot drop down the hole (and for neatness).

Edit: Forgot to mention an important point, the fridge and freezer plugs have already been pushed through their respective holes. Now I am waiting the electrician the fit the power outlets.