Dare I say it, "Installation, and later, replacement."
You install it, and no-one ever tests them. Although it says "Test monthly" on it.
And the replacement after it stops providing power, which is usually some time after it stopped acting as a GFI.
Personal opinion: Where required, and the idea behind its operation is fine. Do not deny the need for them. Unfortunatley, manufactures know full and well the product is flawed. The weak circuit design is "planned obsolesence", as they know it will only operate for a limited amount of time before it needs to be replaced. (It's a cash cow) And most, when they do fail, leave the circuit un-protected. Although they have been required, and on the market for some time, have had little product improvement. GFCI's should have been designed "Fail Safe" long ago.
