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Comment by codingdave | Hacker News Reader

> The lamp flickers when other current-hungry appliances turn on

That should not happen. There is likely a problem somewhere in the electrical system. We used to have similar problems in our home, hired an electrician to help track it down... they gave our home a clean bill of health, but called the city... long story short, they found a problem in a transformer a couple blocks away from us. It had been impacting many homes, and they were shocked nobody had call it in as a problem before us. But apparently, everyone just thought, "Oh, flickers are normal when appliances kick on, right?"

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Ah, this does seem quite plausible--my local power utility doesn't seem super competent, and my landlord doesn't seem particularly excited about maintaining my house :)

Wait. This isn't normal?!

I have the exact same thing happen here.

Whenever the bathroom heat lamp (well, lamps - 2 x 275W, 240V) turns on, I clearly see the lights in whatever room I'm in dip for maybe 10ms.

This used to happen with the old incandescent lamps from years back, but still happens with the newer CCFL types too. Has never not happened.

Huh. Something to keep in mind, particularly for whenever I'm in an environment with access to competent management/engineering ;) (I just know if I tried bringing it up with the current landlord I'm almost certain I'd be authoritatively told "that's normal"...)

I have the same issue every time the air compressor is turned on.

Is it not? I thought the motors inside of them caused that to happen?

Not according to the electricians who fixed it for my neighborhood.

Yes and no. Motors pull a much higher current when they're starting up than when they're running, so your wall socket voltage is going to dip when you start a motor. That said, it shouldn't dip enough to be particularly noticeable, and if it is then that can point to a problem in your power supply or wiring.

It might not be noticeable, or as noticeable, with a 150W incandescent bulb, which has thermal inertia in the filament. What's going on here is that these are fast LEDs.

On the flip side, mains-voltage LEDs generally have built-in power supplies which should lead to them actually showing less dimming during brief voltage dips.

Some mains-voltage LEDs in fact flicker at twice the mains frequency! This is visible when you turn your vision, or when something moving, like rotating fan blades, is illuminated.

The Phillips flood lights in the track lighting fixture in my kitchen are like this.

They contain some sort of very light-weight power supply to rectify the line voltage and adapt it to the LED, but there is no LC capacity in it to even smooth out the 120 Hz ripple.

There is no room in those bulbs for the electrolytics/inductors that would be required.

If you got enough of a draw from one device in your house that lights flicker, the safety switch should probably trigger.

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