The oven was still on.
The door was locked.
And the food inside was starting to burn.

I was three-quarters of the way home from the grocery store when I got a frantic call from my elderly neighbor:

“Sami, the oven won’t shut off. It’s scorching hot. I tried everything. It’s locked, and smoke is coming out.”

I told him to kill the power at the breaker — but he didn’t know where it was.

Five minutes later, I reached his house.
Smoke was curling from the oven’s edges.
The OFF button did nothing.
I had to shut down the power manually at the panel.

Two hours passed before the oven cooled…
…and the door finally unlocked.

Naturally, I was curious.
Not just as a neighbor — but as an engineer.

That oven model is common in our community.
So that weekend, I opened up the controller board.

The culprit?

A normally open (NO) relay that had failed closed after years of thermal cycling.

• Fatigue had bent the contact arm until it stuck.
• This forced the oven into a runaway self-cleaning mode.
• The OFF button? Useless.
• Power cycling? No effect — the contacts had welded.

The problem wasn’t just the relay.
It was the assumption baked into the design:

That the NO relay would always open when power was removed.

But the system never accounted for:

• Mechanical fatigue
• Redundancy or fail-safe design
• Component-level failure
• What happens when the failure mode is the safety system

Just a dangerously optimistic assumption.

I reported the issue—not to ask for a replacement.
But to raise a serious safety concern.

Their response?

“The warranty has expired.”

Not exactly what you hope to hear when reporting a potential fire hazard.

It reminded me of something I posted recently:

• Requirements must go beyond the obvious
• Safety is never guaranteed by default behavior
• Edge cases matter — because someone will live in one

What looks like an edge case in the design lab…
Can become a crisis in someone’s kitchen.

What’s a failure mode you’ve seen ignored — until it became a crisis?

About the Author

Sami Joueidi holds a Master’s degree in Electrical Engineering and brings over 15 years of experience leading AI-driven transformations across startups and enterprises. A seasoned technology leader, Sami has led customer adoption programs, cross-functional engineering teams, and go-to-market strategies that deliver real business impact.

He’s passionate about turning complex ideas into practical solutions, and about helping teams bridge the gap between innovation and execution. Whether architecting scalable systems or demystifying AI concepts, Sami brings a blend of strategic thinking and hands-on problem-solving to every challenge.

© Sami Joueidi and www.cafesami.com, 2025.
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