Lights Out Isn’t Power Off
He began his career in the electrical trade by engaging in construction activities at a potash mine located west of Saskatoon, Saskatchewan. Since then, he has accumulated experience in various facets of the electrical trade, including construction, commissioning, and maintenance.
Lights Out Isn’t Power Off
There’s a new quiet in some panels now. No moving parts no mechanical operations—just a bar of silicon that sees a fault, thinks in microseconds, and pulls the current flat before anyone has time to say what almost happened. The promise is speed: solid-state breakers that switch with semiconductors instead of metal, trading moving parts for wide-bandgap devices that operate and clear a fault so fast the arc can’t grow teeth. Makers love to say the chance of a dangerous arc flash is “almost zero,” and their lab data shows interruption in the single-digit-microsecond band. The physics are real; the caution is too. “Almost” is not policy. “Almost” is not procedure.
So that's why we have the new CSA C22.2 No. 354, Solid-state circuit breakers. We’ve watched this go from brochure to busway. The first UL-listed products under UL 489I arrived a few years back, giving solid-state breakers a proper certification lane instead of trying to squeeze them into a purely mechanical rulebook. They’re turning up where speed is king - UPS front ends, DC distribution, EV infrastructure - places where a fault that dies in a microsecond doesn’t have time to grow. That’s progress worth having.
But let me tell you about the day the room went dark and someone thought that meant safe. He’d opened the vacuum breaker feeding the area, saw the lights go out, and figured the job was ready. He was working on a 3 phase system the way a lot of power distribution does, and the darkness lied to him: one phase was still alive. The rest of the tests—the ones that turn “looks off” into “is de-energized” - never happened. He reached in and met 35 kV. It was a long day for all the wrong reasons.
That is the oldest lesson in a new world: test before touch. You don’t get to assume. You don’t get to infer from a pilot light, from a HMI, from the sound a cabinet makes - or doesn’t. You don’t get to call a system safe because a breaker handle is in the right position or a status LED is green. The electrically safe work condition is a thing you make, not a thing you wish: isolate with a lockable, physical device; verify absence of voltage with an instrument; ground if required; and only then put your hands where your eyes can’t see. That’s not my opinion; it’s the spine of CSA Z460, NFPA 70E and OSHA’s electrical work rules.
Solid-state breakers don’t change that spine. They’re phenomenal as first responders - the fast sensing and faster operation that keep incident energy from growing - but they are not a substitute for a visible, mechanical isolation point in a lockout/tagout program. The law still expects an energy-isolating device that physically prevents transmission of energy, and your procedure still expects you to prove dead with a tester, not with faith. If you add permanently mounted absence-of-voltage testers into the design, make sure they’re actually listed for that job (UL 1436) and treat them as part of a procedure that still ends with a meter in your hand.
So yes, celebrate the speed. Wide-bandgap devices - SiC and GaN - give us interruption times that used to belong only to lab demos, and they can take a sledgehammer to fault let-through when they’re placed and coordinated well. But build your safety like you always should have: a breaker that thinks fast, a switch you can see, a lock you can touch, and a test you can trust. Darkness is not proof. Silence is not proof. A status bit is not proof. Proof is a process, and the process is what sends everyone home.
We’ll keep saying it the same way until it’s boring. Because boring is the point. “Off” is a hope; “open and verified” is a fact. The new gear gives us better hopes than we’ve ever had. The old habits are still how we make them true.
Just my thoughts
Stay Safe
Norm
