Inline Electric Timer Switch

First THANK YOU, RC, for an on-topic post.

Whats the total cost of what you're trying to protect? (including risk, cost accrued if out of service)

Nothing will save you from a direct lightning hit of course.

Most people, would buy a "surge protector" power strip. Since prices are under $100 USD. They are subcategorized by the "Joule rating" I wonder how many consumers know what that means, and how much is enough? "3330-joule surge protection rating – More joules mean more protection! " Ah, OK. Thanks. But how much do *I* need? "As much as you can afford, of course!"

I assume the manufacturers just use whatever the device (MOV) inside is rated for. I would look for a model that offers lifetime warranty, insurance and support.

For Industrial grade protection, I'd step up to a UPS (uninterruptible power supply) with integrated surge protection. A better choice, also because it will manage both long-term high- and low-line voltage situations. Subcategorized by "VA" (~ continuous power deliverable). So, what to buy, is closer to being answerable for average person, if they know about how much power their PC equipment is drawing. Then I would derate, double that total when shopping for the UPS.

cheers, RS

That 'computer equipment' has sacrificial parts, and the fancy PC only needs a $50 replacement power brick when the surges kill it. The third solution is to plan, somewhat, for the larger surges by making the failure modes graceful and repairable.

A friend in an urban home got my last ferroresonant power supply, so I don't have a really good surge protector any more, and for a few decades now, I haven't missed it.

What about using a timer such as used for saunas or fans, etc.? I'm sure you can find others. Get a real one, not an Amazon electrocution clone.

Home Depot for example:

John :-#)#

I must be missing something. Surge protector socket adaptors or outlet strips are common and cheap. So are socket adaptors with timers. I didn't find any that did both in my brief search, but combining them would not be hard.

Computer equipment of significant value is usually connected to a UPS, which will have surge protection.

Wow! Home depot won't even let me look at that page. I'm in Puerto Rico at the moment. lol

Yes, I've been looking at these, but I was hoping to find something ready to use rather than an erector set. My main complaint about building something is trying to make the box look nice. I found and outlet strip with a 6 ft, 14/3 cord. Add a box in the middle with this timer switch and the job is done.

The timer is sold locally. The outlet strip would need to be shipped to the store in Virginia or Maryland and brought to PR in my bags. The outlet strip is decent enough looking, but most switch boxes are a dog's lunch. It would also need to have good strain relief for the two cables.

Have you looked at these - bottom of page - Time Delay Relays?

You could use an old ceramic or bakelite tube socket and mount that in your power bar.

John :-#)#

I have no idea what you think I am looking for. But this isn't it. Thanks for the try though.

I had a quick look at the equivalent of "Home Depot" here in Norway. I found dozens, with prices of about $10 upwards.

I don't know the ratings or how big surges they protect against. We have extremely stable and reliable power in Norway, and I guess they sell devices aimed at the local market rather than for places with more variable power. Lightning is probably the main cause of surges here, so they will be designed to protect against that.

Your microwave broke. It happens. We have no idea if it was a dried-out capacitor, a worn out part, a manufacturing fault, or anything else, where a power surge might have been the last straw. But okay, based on your microwave you want a surge protector but not the surge protector that you had on the microwave. Yes, I think we are all missing something here - your secret specifications.

Why use a mechanical timer when an electronic one will work? (And the egg timer I have is a little "hour glass" with falling sand - good luck integrating that technology with a socket!). Go to your Home Depot, or whatever, and buy a timer socket that supports the range you need. Problem solved.

Microwaves may be essential appliances for computer users, but I've never heard them considered "computer equipment".

People use UPS's for computers because they don't like random shutdowns. If you live in an area that experiences a lot of lightning or other power surges, a surge protector on your expensive TV might be a good idea.

I doubt if the isolation provided by a simple timer switch will stop a lightning strike jumping across the contacts. I have seen 1" sparks!

Is it surges or brownouts or repeated reconnects doing the damage?

I have never yet seen a PC or a monitor fail and a close lightning strike last year I had a calorific spark jump from my scanner to the ADSL router. To my absolute amazement both survived unscathed. Various neighbours phones and mains powered alarm clocks were toast though.

What can do a lot of damage is repeated retries of distribution circuit breakers on for a couple of seconds and then off again several times when there is an intermittent or borderline fault.

A relay to ensure stuff stays off after a powercut might help you a lot.

That is pretty much all I have semi industrial grade 6 way rail in an extruded aluminium case and protecting everything of any value. It has a MOV is working indicator which so far has usually stayed lit every time. Officially it has no user replaceable parts but Rapid stock them....

A UPS is ideal since that will handle all situations including mains failure. I know for a fact that my PC will run on pretty much anything between 100-250v ac 50Hz. I only realised that the mains had lost a complete phase (not mine) when I tried to make a cup of coffee and the last remaining filament bulb in the house dimmed noticeably. It took forever to boil a kettle!

LED lamps and SMPSU just draw ever more current as the voltage dips.

I suspect US domestic market gear will croak at a much lower voltage than Japanese or UK PSUs and some of it doesn't get on with 50Hz mains either (they cut the transformer tolerances *that* fine).

I think a mechanical timer in the power cable of a computer sounds like a PITA, since it is bound to turn off just before you save some important document.

You could make a motor-generator set with a foot-long plastic shaft between them. That should prevent damage to anything other than the motor, even in a thunderstorm, though it will have significant losses all the time. If you make sure it is noisy, someone might remember to turn it off.

About 25 years ago I made a thing with a wall-wart plugged into the same power strip as the PC and peripherals and a buzzer built into the case of the PC. It had some simple logic and a timer so that it would make a very annoying noise after a few seconds if the wall-wart was powered without the PC being powered (i.e. when they shut down the computer but failed to turn off everything at the wall afterwards). It would also make the annoying noise if the PC was turned on without the wall wart being powered (to discourage anyone defeating the alarm by unplugging the wall wart). It mostly did achieve the desired behaviour, but was generally disliked by everyone who used that computer.

That will depend on the nature of the distribution network, age of equipment, how the lines are physically routed, etc.

I'd make the same argument re: a solid-state switch; unless you can characterize things more fully, you may see the switch fail.

Many new "electronic" (wired) phones have only nominal protection from fast/large transients. Often a pair of zeners acting as a clamp (and if they fail shorted, the line is busied out).

When I lived in the midwest, outages weren't particularly "clean". You'd often get a warning flicker/brownout and, if you were on your toes, you'd unplug anything that didn't like the on-off-on-off-on-off-on-...OFF that would follow. (took me some time to realize the value of a UPS!)

A lot depends on the design of the PSU *and* it's load. E.g., my PCs have

1100W power supplies but aren't loaded anywhere near that much (the UPS on the workstation I'm presently using claims ~200W... quite a pig by today's standards but that's got a pair of GPUs and several HBAs inside -- along with 4 rust spindles). OTOH, when all the cores are running at 100% load factor and the GPUs are actually *doing* work, that figure climbs noticeably!

But, while some of my other SFF/USFF boxes get annoyed at power glitches, these

*tend* not to notice.

Yes, that's my point. You can call these "surge protectors", but they have no rating and even if they have a rating, there's no reason to believe any numbers you read. They are worthless junk and are not surge protectors.

No, they are designed to make a profit. There is zero accountability for their "surge protector" claims, so they use the cheapest, most minimal components that will not protect anything. Lightning is the hardest surge to protect against as it has a hugely wide range of surge. I used to repair burglar alarms and one system had developed opens in the perimeter loop every place where the wire went through the same hole drilled in the joist as the AC wiring. There was enough voltage that an arc passed through both insulations and enough current to melt the perimeter wire in two forming little balls on the ends of the broken wires. The panel was fried of course. Any surge protector you can buy for $5 would have been destroyed and not protected equipment against damage.

With no real way to compare surge protectors and no knowledge of what rating is required, the best bet is to disconnect the appliance.

Sometimes it is very hard to discuss things with you because you ignore so much of what is provided. There is decades of history behind this. You are in no position to argue that cap dried up in an 8 month old microwave. Please just stop posting silly ideas and assuming others know nothing, such as the idea that you can buy "surge protectors" that are worth anything for just $10. They are not surge protectors, they are outlet strips.

Ok, I think we are done here. If you don't even know what sort of mechanical timer I'm talking about, you must live in a cave. Didn't I post links?

Yes, we are done here.

OK, so you want a surge protector but you won't buy anything called a "surge protector" because they are all useless.

You told us your microwave broke. You didn't say it was 8 months old, or that you have "decades of history" (whatever that might mean). You said it broke, and you gave /zero/ information about why you leapt to the conclusion that it was a worthless surge protector. And /I/ am the one being difficult for asking questions!

You posted one link (as far as I noticed) to a mechanical timer. You've given no clear indication as to why you want it to be /mechanical/.

We are seeing the usual pattern for your posts looking for information or help. You give a fraction of the information people might find useful, with little detail and even less idea about why you want one solution and reject others. Then you jump and people who try to help, and argue with them or insult them for failing to read your mind.

It's a good job posters in this group either have memories like goldfish, or an obsessive need to try to help people, or you'd get no replies at all.

You said, $10. That's not a surge protector. That's an outlet strip regardless of what moniker they put on it.

I don't know why you would assume the OP is an idiot and knows nothing about "surge protectors" that have been around for decades, posing as useful equipment, but actually being pretty much worthless. Because such surge events are normally very sporadic, people can buy them and think that their equipment has been protected for the last 10 years. In reality, there simply have been no surges that would damage the equipment in the first place.

I didn't think it was required to point out that an electronic timer would be subject to the same surges the electronic equipment is to be protected from. Isn't that very obvious??? If you saw the link to the mechanical timer, what is then unclear? I even explained why the electronic timer is less desirable, but you seem to have ignored that content.

I'm not jumping you, I'm explaining that your assumptions are obvious mistakes. Why do you not understand that an electronic timer would suffer the same damage as the electronic equipment being protected? Why do you insist on arguing about it when I tell you it needs to be mechanical?

You, in particular, have a tendency to go off in strange directions, and make unreasonable assumptions. Like assuming I wanted to protect computer equipment when my OP said, "various electronics" and "appliances". I only mentioned computer equipment when I asked about typical protection because I've never met anyone who protected a microwave while computers are often protected.

Ok, sorry to have bothered you, but at least you must have found this entertaining or you would not have posted so many times.

Lightning rod systems will. They include more protection than just the rods (now called "air terminals"). Not cost-effective for most of us, but very useful for some.

Excellent information on surges and surge protection is

"How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE. (And in a near miracle it is free.) Some of the information is specific to the US.

Starting pg 25 talks about joule rating. In the US there is no definition for a suppressor joule rating. As a result some manufacturers use a deceptive rating which puts honest manufacturers at a disadvantage, so some manufacturers do not provide a joule rating.

The max surge with any reasonable probability of occurring, US, residential, typical overhead urban distribution, is 10kA per service wire. Pg 18 has recommendations for service panel protection. (also see joules that can make it to a plug-in suppressor elsewhere)

When using a plug-in surge suppressor all wires (power and signal) to a set of protected equipment needs to go through the suppressor. The voltage on all wires is clamped to the ground at the suppressor. (The same thing happens at a service panel suppressor, which needs voltage clamps on incoming signal wires adjacent.)

UPSs that are not always on-line don't themselves provide surge protection other than the separate circuit. Overvoltage (IEEE guide pg

15) can rapidly destroy surge suppressors.

The IEEE guide, cited elsewhere, does not indicate that "Most 'surge' protectors are nearly worthless". Buy one from a competent company. And UL listed provides at least a minimum floor.

MOVs fail by the voltage at which they start to conduct lowering after hits totaling at least the joule rating to the source voltage, and the MOV goes into thermal runaway. All UL listed suppressors should have a disconnect for failing MOVs that operates at least partly on heat. Recent UL listed suppressors disconnect the connected load with the MOVs (or inform you that they don't). UL listed suppressor? Do you know it failed? Was there a surge? Is there a reason to believe the microwave didn't just fail (fairly new is not a guarantee)?

Suppressors with protected equipment warranties are available. They are possible because of the disconnect feature above, and the low amount of energy that can actually reach a suppressor (in another post).

I have not read that "they have a relatively short lifespan".

The NIST surge expert investigated how much energy can reach MOVs in a plug-in suppressor (with no service panel suppressor). Branch circuits were 10m and longer, and surges coming in on power wires were up to 10kA (which is the maximum probable surge). The maximum energy was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. Plug-in protectors with much higher ratings are readily available. (This is US, and there are a couple features that may be different. One is the neutral-ground bond in services. The other is arc-over described below.)

There are 2 reasons the energy is so small. One is that at about 6,000V there is arc-over from the service panel busbars to the enclosure. After the arc is established the voltage is hundreds of volts. Since the enclosure/ground/neutral are connected to the earthing system that dumps most of the incoming surge energy to earth. (This would also limit the voltage across switch contacts.)

The second reason is the impedance of the branch circuit wiring. A surge is a very short event. That means the current components are relatively high frequency. That means the wire inductance is more important than the resistance. The branch circuit impedance greatly limits the current to the MOVs, which greatly limits the energy that can make it to the MOVs.