We used to leave it on overnight to empty in the morning.
One night it caught fire - in the electrics bit inside the door.
By the time we noticed (midnight, DH was still up - the rest of us were asleep) there were flames coming out from under the countertop all along one side of the kitchen.
We called 999 before the smoke alarms caught on.
By the time we'd woken everyone up and we'd got the kids outside (screaming, terrified) the whole kitchen was ablaze.
The fire fighters took 4 minutes to arrive apparently. Longest four minutes of my life. You always hear that the most frightening thing about a fire is how fast it takes hold. That's one of those things I didn't really understand until I saw it.
We put the kids into the car. Still hysterical. A neighbour came and got them at some point and took them into their house. Gave them blankets and warm milk.
Then I had to answer questions, like "how long is the driveway?" and "how may steps in which direction to reach the back bedrooms?" and "is your gas turned off?" and I didn't know the answer to anything because my house was on fire.
And the fire fighters put it out and showed me hours later how it could all just reignite. They were amazing. I cannot put into words how grateful I am to have these able, calm, competent people on the end of an emergency phone number.
And then they left and every single thing that we owned was either gone or covered in soot and stank of putrid acidic plastic smoke.
We do not put the dishwasher on at night any more.