Where I live, there are power cuts that are becoming more frequent. A couple of weeks ago, an AC unit died and the technician told us that he’s seen a lot of those recently; apparently, the power goes out when the unit is on, and when the power returns, the surge can fry some rather expensive circuits. We had to buy a new unit, and they’re not cheap.
The thing is, these units don’t have a physical switch and are connected directly to the feed. If the power goes out, there is no way to switch them off or uplug them; you’d have to go all the way to the circuit breaker and cut the feed yourself.
So, I had been planning on doing that; if the power goes out when the AC unit is out, I’d go to the electric box and open the breakers myself; then when the power returns, I’d close them safely. Then, a few moments ago, the power went out and came back within a minute, while I was still putting my shoes on. Nothing burned this time, but that plan is clearly not gonna work (also, clearly it wouldn’t work when I’m asleep).
All that said, I do wonder if there’s some sort of breaker that would trip when the power goes out, and that I could reset manually when it’s safe, so the appliances are protected from the surge when it returns? I haven’t been able to find one, and am not even sure if my technician’s information holds water. I’d be grateful for any information.
I am unaware of such a breaker and with my central a/c unit there is a time delay feature preventing it from activating too soon after shutting down. Even when I turn it on, it takes several seconds before the unit activates. I am not an electrician but if a power surge damaged your a/c it seems logical to me you would have sustained other damage to more sensitive devices such as computers, digital clocks, and perhaps your refrigerator compressor.
You can get whole house surge protectors installed. A bit pricey for good ones and need to be installed by a pro.
But they can save a lot of money in fried electric appliances. May be cheaper to install one just on the AC line.
Surprised that the AC unit does not seem to have adequate surge protection already built in.
If that problem occurred here in my apartment here in Germany (it does not because what the OP describes in utility service reliability and in AC appliance design frankly is not up to 1st world standards; it’d be torches-and-pitchforks time for the respective companies) I’d augment the household circuit breaker for the circuit with an undervoltage trip module such as this one
Many US utilities will rent you a whole house surge protector. It’s a gizmo that fits on the back of the electric meter. So they come out, yank your meter out of its socket on your meter panel, plug the surge protector into the panel’s socket, then plug the meter into the surge protector’s socket. Once installed it just looks like your meter is a couple inches thicker/taller than it used to be. Most utilities charge $0 for that 10 minute installation call. You might end up paying what seems like a bunch of money over the next 20 years, but the cost per day is close to zero.
As a separate matter …
Current code in most of the USA requires a shut-off switch or circuit cut-out within arm’s reach of an HVAC unit. That’s to cover for the case of a workman getting into the unit with the power still on and getting a nasty surprise. By interrupting the power right there, they’re sure there’s no juice inside before they stick a screwdriver in there.
These did not used to be required and there’s typically no retrofit requirement until the HVAC unit is replaced entire. So depending on the age of your building and HVAC unit, you may not have one. But if you do, that becomes another place for you to go to to manually cut off power after a failure and before the power returns. Getting to your HVAC unit may be easier or harder than getting to your C/B panel. But now you know to at least look for such a switch or cut-out.
This doesn’t solve your “automatic cut-off until I reset it” issue, but it may make you more able to survive longer outages by getting to the cutoff sooner.
The USA has quite a tradition of preventing utility companies from keeping citizens’ trees out of their wires. The freedumb of the individual tree owner is more important than reliable power for all.
Regulators favoring ever-so-slightly lower prices by not requiring actual maintenance of the infrastructure is another deep-seated and long-standing issue.
We were watching TV one day when the audio amp started smoking. Upshot was a number of appliances - stove, microwave, audio amp, a few small things - died from what must have been a small surge. No indication why, none of the neighbours had problems.
As part of the fix, we got a whole home surge suppressor installed. It appears to be connected to both sides of the electrical panel and proveides (supposedly) a decent amount of protection from the initial surges that often happen when power is restored.
But I agree - I’m surprised on a very expensive piece of hardware like a n AC unit, that there is not a reasonable amount of surge protection built in - particularly if it is “always on”. But then, much stuff is built to minimal code requirements.
Are we talking about a window or wall air conditioner here? Old units, or perhaps even newer but very cheap ones, the types that just have a couple of dials for controls, don’t have delay timers. Those are specifically to prevent the compressor from turning back on within 2-3 minutes. It’s not that it would “fry some circuits” (a statement that requires clarification), but restarting a compressor without allowing a few minutes for the pressure to equalize means that it will be under an extreme load, more than the circuit can handle, thus tripping the breaker. This would only happen after very short outages, like just a couple seconds, or if you were to fiddle with the temperature dial. New units have that delay timer to prevent this. It should be mentioned in the user manual, and often it’s even written somewhere near the controls. That obviates the need to shut off anything yourself.
The 835 is a manual reset intended to prevent the unintended restoration of power
to a gas or electric powered appliance. In the event of a power failure or the release
of a connected control switch, the 835 interrupts power to a gas valve or electrical
contactor, shutting down the appliance. The fuel or power supply to the appliance is
restored only after the control switch has been set, and the 835 has been manually
reset by pushing the reset switch on the 835. When power is being supplied to the
gas valve or electrical contactor, the red indicator light is on. The red indicator light is
off when power is not supplied to the gas valve or electrical contactor.
This may not have the voltage/current rating you need, but there are others out there.
Unlike a typical residential circuit breaker, I don’t believe a MRR provides any overload protection; it’s just there to require human intervention to restore power after a power interruption.
We are assuming that the technician provided the OP with a correct explanation. A surge might take out the control board of an A/C unit, but that is repairable (although expensive - for an old enough system it might make sense to replace rather than repair). Damage requiring replacing the whole system sounds like a motor burned out due to a brownout (period of voltage too low for a motor to run but high enough to cause the stalled motor to burn out) rather than a surge.
That has never been true, at least not in places where I have lived.
Around here, if the trees are starting to grow into the power lines, the power company will come and trim back the tree. They won’t be at all artistic about it, so don’t be surprised if they just cut straight down and straight across in an L shape to take a big ugly notch out of the tree. They only care about getting the branches away from the wires. They don’t give two hoots about what the tree looks like afterwards.
In many places, the power company will also charge you for the tree-trimming work.
In a small town like mine, the power company doesn’t have the time to inspect all of the miles and miles of power lines running through all of the surrounding rural areas. The power company’s first indication of trouble might be when a tree branch takes out a power line.
My 1919 Chicago home has two! There’s a small fuse box, about the size of a cigar box, in the attic, near the service entrance, where the power line hits the house. I think it has 4 or 6ish fuses (don’t remember and it’s like 999 degrees up there now). The other is a more conventional looking cabinet in the basement.
Both use those glass Edison fuses, though I’ve never blown one in almost 15 years now. The one in the attic has a label from the installer where the first 2 digits of the telephone number are letters which puts it to the mid60s or earlier.