MacBook Air watts draw (for UPS)?

[winterquilt]

I have an old MacBook Air (A1237 MacBook Air 1.1 MB003LL/A) and would like to know the watts drawn by the device, but I can't find anything on Apple's website about it, where do they hide this info?

I would like to connect it to a UPS and so I need to know the peak amount.

Should I be looking at the MagSafe transformer, rather than the MacBook?


Thanks.

 

[Weaselboy]

What you want is what Apple calls the "Environmental Report" for that model. That will show the power usage. I can't find one for that older model, but this report for a 2012 model Air shows about nine watts. I would not think yours would be much different.

 

[winterquilt]

Thank you very much for going to the trouble. Perhaps they didn't have "Environmental Reports" at the time they introduced the first MBA?

I'll ask Apple if they have one for it and report back if they do, but it's likely that there won't be much of a difference like you say.
[doublepost=1475709223][/doublepost]Here is an archived report: https://support.apple.com/kb/SP8?viewlocale=en_US&locale=en_US

It doesn't list the wattage, back then the "Environmental Reports" were only just being introduced (that year apparently: 2008), there may be a "Progress Report"? Anyway, I'm going to use a power meter to check to wattage on full load as even those numbers are when the machine is idle.

Thanks!

 

[Cordorb]

many people get a low cost kill-a-watt unit to monitor a/c power usage.

this unit can show peak load and better still load overtime

this way you get total power used including the AC to DC loss in any power adapter and the unit will show watts AND volt-amps which most UPS use.

 

[winterquilt]

I bought the following:

https://www.amazon.co.uk/gp/product/B01DSQ30FO/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1


I'll have to experiment with it, but it does tell me the low and the high, that much I can tell. I have been looking into the formulas for calculating amperes, whats etc..

 

[winterquilt]

I have just tried the meter and found that the MacBook drew a maximum of 35W (of a possible 45W).

 

[DeltaMac]

I am curious as to why you would want to provide UPS space for a device that is naturally battery powered.

 

[Weaselboy]

I have just tried the meter and found that the MacBook drew a maximum of 35W (of a possible 45W).

Wow... big and surprising difference from that 2012 model.

 

[winterquilt]

Wow... big and surprising difference from that 2012 model.

That was at peak, when I was pushing it hard, otherwise it was less. But only single digits when closed, not even idle I think.
[doublepost=1475892924][/doublepost]

I am curious as to why you would want to provide UPS space for a device that is naturally battery powered.

Now you come to mention it, you're right.

The whole idea behind getting a UPS was when I moved from a laptop to a desktop and noticed that power outages were an issue. However, since heavily researching into UPS design and terminology and learning that laptops will actually never feed directly off of utility power, instead employing Automatic Voltage Regulation and drawing DC from the battery. So, I need not worry as such, but it's because I use one on my desktop I just thought I'd plug it in, but the only thing I may need worry about is to use the surge protection options instead.

I guess my mind is in a lot of places right now, there's a lot to research when choosing a UPS!

Thanks.

 

[DeltaMac]

When the lid is closed, then the laptop is sleeping (or in hibernation if you can use that mode, even less power), and sleep should be less than one watt. I do think you have to let the system "settle" into sleep, which might take a couple of minutes. And, you can unplug the power adapter, so it is definitely in true sleep (and the only drain will be on the internal battery.)
I still am curious why you would consider using a device that already has its own battery, with a UPS.
Isn't that just a repetitive redundancy...
(I see you already answered that part about redundancy...)
[doublepost=1475893726][/doublepost]IMHO, my main question about using a UPS is: Do you need to keep working as normal, despite a general power failure - or, do you only need to keep everything up long enough to back out of what you are doing, and shut everything down safely?
The second might be done fairly cheaply. The first may require not just a UPS, but could mean an auto-start generator to make it all good. The range in between can make for a lot of reading, with lots of choices to consider, eh?

 

[RedTomato]

(diagram copied below)

I don't quite understand these figures.

- Why is there power consumption when the laptop is off?
- Why does the power consumption vary with the wall voltage?
- Why does the power consumption increase at the same time as the 'Power adapter efficiency' figure increases? (I would expect to see an inverse relationship between adapter efficiency and power consumption.)

 

[Weaselboy]

I think it is like those wall wart DC adaptors you have around the house for different gadgets.... even though nothing is attached to the wall adaptor it uses a little power for its own circuitry.

On the other two... I don't know, but it is pretty close in both measurements across the different voltage levels.

 

[winterquilt]

When the lid is closed, then the laptop is sleeping (or in hibernation if you can use that mode, even less power), and sleep should be less than one watt. I do think you have to let the system "settle" into sleep, which might take a couple of minutes. And, you can unplug the power adapter, so it is definitely in true sleep (and the only drain will be on the internal battery.)
I still am curious why you would consider using a device that already has its own battery, with a UPS.
Isn't that just a repetitive redundancy...
(I see you already answered that part about redundancy...)
[doublepost=1475893726][/doublepost]IMHO, my main question about using a UPS is: Do you need to keep working as normal, despite a general power failure - or, do you only need to keep everything up long enough to back out of what you are doing, and shut everything down safely?
The second might be done fairly cheaply. The first may require not just a UPS, but could mean an auto-start generator to make it all good. The range in between can make for a lot of reading, with lots of choices to consider, eh?

It's interesting that you say that because before UPS units begun to become affordable there were "Surge Suppressors" and "Line Conditioners" which would either behave like a fuse between a large current and your equipment, or to filter the noise out of AC lines. Both have a detrimental effect, but one is instant and the other accumulative over time (like hearing loss if you're a shooter and don't wear ear protection). Electronics in todays computers are so small that they're hyper sensitive now, unlike the electronics back in the 70s and early 80s, so technology like Automatic Voltage Regulation is a good idea, it just is.

Since then UPS units have proven to be the best of both worlds and improve upon these technologies, so there is the every day degradation that can be avoided and the sudden death scenario too. Like I said, I was coming from the laptop (MacBook) world and noticed it instantly. I never want to my desktop to just cut out, no way, just rebuilding Aperture is a nightmare!
[doublepost=1475973818][/doublepost]

I don't quite understand these figures.

- Why is there power consumption when the laptop is off?
- Why does the power consumption vary with the wall voltage?
- Why does the power consumption increase at the same time as the 'Power adapter efficiency' figure increases? (I would expect to see an inverse relationship between adapter efficiency and power consumption.)

Don't take my word on any of this, but I think:

- It could be that even if the MacBook Air is asleep, the AC utility power will go into the transformer (MagSafe) and just back out again as it's not needed, maybe?

- There is True Power and Apparent Power and those vary depending on the efficiency of the device they're powering. It could be an efficiency issue? The rating shows that around 13% is being lost to harmonic current.

- To make up for a loss in amperage the utility will compensate by upping either the voltage or current to fill the gap in power distribution, maybe it's an efficiency issue again?


Like I said, I'm not sure, but it's my guess from the research I've been doing.

 

[westom]

It's interesting that you say that because before UPS units begun to become affordable there were "Surge Suppressors" and "Line Conditioners" which would either behave like a fuse between a large current and your equipment, or to filter the noise out of AC lines.

Add spec numbers to that conclusion to learn that a UPS does not protect hardware from potentially destructive transients. It is temporary power so that unsaved data can be saved. It does not even claim protect hardware - once we include spec numbers.

Power from a UPS can be so 'dirty' as to be problematic to motorized appliances. That same 'dirty' power is ideal for electronics.

Voltage can drop so low that incandescent bulbs dim to 50% intensity. Also problematic for motorized appliances. And perfectly good voltage for electronics.

To understand what a UPS does and does not do must be based in specification numbers. Any recommendation that does not include numbers is suspect.

Best hardware protection is located elsewhere. If one appliance needs that protection, then everything needs that protection including a dishwasher, clocks, furnace, bathroom and kitchen GFCIs, refrigerator, and especially smoke detectors. Other superior and less expensive solutions protect everything.

Most all computers consume less than 350 watts - including those built by computer assemblers with 600+ watt PSUs. Apparent by using a Kill-A-Watt. A UPS is typically made as cheaply as possible. So a system that consumes up to 350 watts is better powered by a UPS that is 500 watts - for many reasons including a battery that typically expires in three years. Then a 3+ year old UPS should still provide sufficient power so that unsaved computer data can be saved.

 

[winterquilt]

Add spec numbers to that conclusion to learn that a UPS does not protect hardware from potentially destructive transients. It is temporary power so that unsaved data can be saved. It does not even claim protect hardware - once we include spec numbers.

Power from a UPS can be so 'dirty' as to be problematic to motorized appliances. That same 'dirty' power is ideal for electronics.

Voltage can drop so low that incandescent bulbs dim to 50% intensity. Also problematic for motorized appliances. And perfectly good voltage for electronics.

To understand what a UPS does and does not do must be based in specification numbers. Any recommendation that does not include numbers is suspect.

Best hardware protection is located elsewhere. If one appliance needs that protection, then everything needs that protection including a dishwasher, clocks, furnace, bathroom and kitchen GFCIs, refrigerator, and especially smoke detectors. Other superior and less expensive solutions protect everything.

Most all computers consume less than 350 watts - including those built by computer assemblers with 600+ watt PSUs. Apparent by using a Kill-A-Watt. A UPS is typically made as cheaply as possible. So a system that consumes up to 350 watts is better powered by a UPS that is 500 watts - for many reasons including a battery that typically expires in three years. Then a 3+ year old UPS should still provide sufficient power so that unsaved computer data can be saved.

Specific number are what I'm after, I'm looking into how to calculate those and what they mean. I already mention that my needs were computing equipment, which isn't medical but not primarily motorised either, the equipment is sensitive however and will be best served by a "pure" sinusoidal wave output. In the case of a laptop it's true that a modified sinusoidal wave would be acceptable, as the power will be drawn from it's own transformer which will filter that anyway, however the modified wave will cause said transformer to become hotter, quicker, and wear it out sooner as a result, which is something I would like to avoid. Desktops, which I have, will need a "pure" phased sinusoidal wave input anyway.

NEVER plug in a dishwasher into a UPS, nor a refrigerator, not even with a load it can manage, which is often out of the realm of the average £500 priced UPS, it will likely damage the UPS. Even if you had a UPS exceeding the Watts required it wouldn't be much benefit without running from a backup generator anyway, and that's not what I'm looking for.

Like you say, it's best to shoot ahead, a UPS powered with enough fresh, or well calibrated, batteries to power above the recommended VA (which is a conservative number by default) will guarantee you that shut down window period. But, in some cases users would like to ride out the storm, so more powerful batteries would be needed, which is fine, but I'm still debating that. There is also the software aspect to consider, a good alternative would be the binaries from Network UPS Tools (http://networkupstools.org), with a dedicated development team this is a good choice.

I am looking to protect from under/over voltage, power sagging, surges, spikes, electrical line noise, harmonic distortion etc.. and YES, a UPS of good quality will filter that out, which sensitive computer components would thank me for, so it's more than just having enough time to save files, it's a constant daily level of protection.

 

[westom]

Specific number are what I'm after, I'm looking into how to calculate those and what they mean. I already mention that my needs were computing equipment, which isn't medical but not primarily motorised either, the equipment is sensitive however and will be best served by a "pure" sinusoidal wave output. In the case of a laptop it's true that a modified sinusoidal wave would be acceptable, as the power will be drawn from it's own transformer which will filter that anyway,

First, understand what happens to 'dirty' or 'cleanest' AC electricity. 120 volts is filtered. Then converted to DC volts. And filtered again. Then converted to well over 300 volt radio frequency spikes. All without any transformer.

That now dirtiest power is converted into rock stable, low DC voltages by regulators, filters, and galvanic isolation. A point made previously and again here. If 'dirty' electricity concerns you, then worry more about less tolerant appliances - motorized appliances. UPS is not recommended for motorized appliance because UPS power is potentially more harmful to those less robust appliances.

Second, many different anomalies must be discussed separately. Clean sine waves and surges are completely different anomalies that require completely different solutions. Other anomalies that also may be discussed are frequency variation, short current interruptions, polarity reversal, floating ground, harmonics, EMC/EMI/RFI, brownouts, overvoltage, and power factor. Which ones are a threat to which appliance?

Pure sine wave is needed by motorized appliances. Repeated because that point was overlooked. Pure sine waves are made irrelevant by how electronics are designed (see above) - since electronics are more robust. AC power is pure enough as demonstrated by so many motorize appliances that are not failing.

A completely different topic is surge protection. Plug-in protectors and line conditioners do not claim to protect from destructive surges. Protector or conditioner that acts like a fuse cannot possibly protect from surges. View numbers. That protector or conditioner must either 'block' or 'absorb' a surge. How does its 2 centimeter protector part 'block' what three miles of sky cannot? It cannot. But fuse must somehow do just that - 'block'.

How do hundreds of joules in a protector or conditioner 'absorb' a surge that is hundreds of thousands of joules? It does not even claim to. It only claims to 'absorb' surges that are made irrelevant by what is already inside appliances - electronic and motorized.

Third, let's avert one anomaly - surge. Protection means one says where hundreds of thousands of joules dissipate. That cannot happen in anything inside a house. Protection means that current must not be anywhere inside a house. It must not be incoming to any appliance. If anything needs that protection, then everything needs that protection. Hundreds of joules in one UPS means even that UPS needs protection.

Subjective claims are also why so many believe a protector or conditioner protects like a fuse.

Fourth, an output from my 120 volt pure sine wave UPS is 200 volt square waves with a spike of up to 270 volts. Perfectly good power for what are more robust - electronics. Square waves and spikes are nothing more than a sum of pure sine waves. So they did not lie. It is a pure sine wave output - as long as claims are subjective. They just forgot to provide relevant numbers such as %THD.

Discussed here and previously are numbers for two anomalies - surges and 'purity'. Above is how electronics routinely convert 'clean' or 'dirty' AC power into dirtiest power. Then best regulators, filters, and galvanic isolation make that 'dirtiest' power irrelevant. Best solution is already in electronics. Concern should focus on anomalies that might overwhelm superior and existing protection. No plug-in conditioner or protector will even discuss those anomalies.

Fifth, discuss another anomaly. Voltage can drop so low that incandescent bulbs dim to 50% intensity. That low voltage is sufficient for any electronics. How often do your bulbs dim that much? A voltage that low is problematic for less robust motorized appliances. So an AC utility will maintain a higher (sufficient) voltage. Or disconnect power to protect motorized appliances. So what is that UPS protecting from?

Blackouts also do not damage any properly designed electronics. Again, best protection is already inside appliances.

To better answer your question, please list each anomaly of concern with relevant numbers for each considered solutions - UPS or protector. Many anomalies are simply connected directly into the attached load by a UPS. A typical UPS only has one function - temporary and 'dirty' power so that unsaved data can be saved.

Which anomalies will overwhelm existing, more robust protection? Which anomaly is of concern?

 

[winterquilt]

Apologies for my absence.

First and foremost I am looking to protect my iMac computer, a simple workstation. I have no need for power tools, nor would I need to rely on this UPS purchase for such tools in the future, this would just be used for microelectronic devices.

"Dirty electricity can cause electronics to perform poorly, especially microelectronics. High voltage spikes, for example, can cause electronic component damage, both immediate and long-term, computer memory loss, program corruption and operating errors. Because electrical pollution can damage equipment and decrease the lifespan of hardware.."

ref: http://whatis.techtarget.com/definition/clean-electricity


There is an extreme here, where "dirty electricity" can be managed with AVR (http://www.apc.com/us/en/faqs/FA158913/), but then then again "high voltage spikes" come into play, by which I take it they mean Thunderstorms? I don't worry about thunder here in London, I worry more about the brown-outs I regularly get and the long term effects it has on my hardware and software. However, reading on CyberPower's website their User's Manual literature for the model "CP1500EPFCLCD" (https://www.cyberpower.com/uk/en/product/sku/CP1500EPFCLCD) states "Surge Protection: Lightning / Surge Protection", which seems fairly definitive (in the technical specification though it does mention under "Surge Protection & Filtering" with a surge "suppression" of 405 Joules), but I wouldn't know what to ask them?

What question could I ask them that you would suggest to back up their claim if indeed they were not forthcoming with the absolute truth?

I read this article (http://electrical-engineering-portal.com/effect-of-lightning-strike-on-electrical-lines) and it makes me wonder how much of that pulse of lightning is actually to make it to my outlet?

I don't think that it's an irrelevance to opt for modified sine wave, I see there is a lot of discussion as to all of the operating equipment that will still function with it, like personal computers. But it will still create more heat than would otherwise be made from a "pure" sinusoidal wave and that increases wear and tear in general, so I'm happy to go with it, I don't mind paying more.

I read that anything below 80V is considered a "blackout", that may be for US power though, I'm UK. I can only find the following: https://en.wikipedia.org/wiki/Extra-low_voltage which states that low/extra low voltage has a minimum threshold of 50V, but I don't think an iMac could operate as normal, if at all, on that, but I don't have any numbers for that.

I see that you prefer to concentrate on over, rather than under, power issues, which makes sense, but then rubbish the abilities for surge protectors and the like to be able to handle these, leaving me with little choice. I personally consider low power and issue, long term wise, especially as I do not have a high cycle replacement rate for my hardware, so I need to avoid long term hardware issues caused by these.

It was mentioned before that if a laptop runs off of it's own battery then why would I need worry about the power issue of it, which made me stop to think. But now I read that power running into a laptop is not all going to the transformer, only some of it, while the rest goes directly into the circuit board, or back to the unity, so laptops need be protected as well, if this is true?

I read that it's best to completely disconnect from the wall outlet during a severe power issue, which really would be rare for London, as there is no better way to protect one's devices. But surely it would have been too late by then? You mention there are no side effects from a total blackout, while that may apply to hardware, it certainly doesn't to software.


My Numbers:

• iMac: 310W
• External SSD: 6W
• External HDD: 36W
• MacBook Air: 45W
• iPhone: 6.3W
• iPad: 13.3W
• Headphone: 1.4W



For my iMac, External SSD, External HDD I need to be protected from:

• Power Failure: total loss of power
• Power Sag: I live next to a giant A/C for the London Underground, it's always on, but one never knows..
• Power Surge/Spikes: above 110% should be manageable by domestic UPSs, anything like lightning should be handled by the power company?
• Under Voltage: I have an A/C and my lady uses a hair-dryer, I notice a momentary dip in the brightness of our ceiling light, the fridge also switches on an off and has this effect, as well as other appliances with our neighbours..
• Over Voltage: As you mention, hardware is more affected by over supply than under, being the way modern electronics is manufactured today
• Harmonic Distortion: not sure, but maybe?

I would like to have a run time of around 30mins for my iMac during a blackout.


For my MacBook Air, iPhone, iPad and Headphones I am looking to be protected from:

• Power Surge/Spikes
• Under Voltage
• Over Voltage

These other devices all have their own internal power supplies and are only connected to the power outlet in order to keep them topped up, but I still fret over spikes supply and the like.


CyberPower seems like a longstanding reputable company with decent macOS software, looking at their PR1500ELCD model, with the formula Battery Voltage * AH Rating * Efficiency) / VA Rating = X
X * 60 = Estimated Run Time in Minutes:

Battery Voltage: 12
AH: 17
Efficiency: 0.9 (90%)
VA Rating: 1,500

ref: http://www.cyberpower-eu.com/support/download/datasheets/PR1000-1500ELCD_Datasheet.pdf

I got 7.3mins at full load, but I'm only drawing a theoretical maximum of 420W, so that would be 20-25mins all in, or 30mins plus with just the iMac (which will never draw 310W anyway). I gather that all claims depend on many factors and that a certain percentage of the total should be reduced in order to be realistic, any info on this?

 

[westom]

First and foremost I am looking to protect my iMac computer, a simple workstation. I have no need for power tools, nor would I need to rely on this UPS purchase for such tools in the future, this would just be used for microelectronic devices.

If protection is not needed for other appliances, then more robust protection inside an iMac and other electronics provides more than sufficient protection. It anything needs protection, then everything needs protection. Only way to deny this is to read subjective claims from APC, Cyberpower, and other who are marketing only to consumers who ignore all numbers.

If disconnecting is necessary to protect, then best protection is to spend nothing on protectors. Effective protection means even direct lightning strikes do not cause damage. Best hardware protection costs about $1 per protected appliance.

Provided is a number for sufficient or low (brownout) voltages. An incandescent bulb at 50% or higher intensity means voltage is just fine. If that bulb dims less, then electronics simply power off. No damage. No threat of damage. Hardware protection means numbers not found in any of those Cyberpower or APC specs. No such numbers existed in that long power because no such protection is even claimed. Provide is another number that was ignored: 50%.

How do hundreds of joules in a protector or conditioner 'absorb' a surge that is hundreds of thousands of joules? Why ignore a sentence that includes numbers?

So again, do you want hardware protection or to protect unsaved data? If 'dirty' electricity causes electronics to perform poorly, then everything we designed is crap - using reasoning from that subjective and technically dishonest citation. Again, stop letting numbers glaze over eyes. Posted was THE 'dirtiest' electricity that is intentionally created in all electronics. Posted with numbers. Go back and read with intent to only memorize those numbers. Best filters, regulators, and galvanic isolation convert the 'dirtiest' possible electricity (ie well over 300 volt radio frequency spikes - see that number) into 'cleanest'. If you want a technically honest answer, well engineers post numbers. Myth purveyors post subjectively - no numbers.

whatis.techtarget.com should have been immediately obvious as a sham. Where is one number that defines a spike, noise, ripple voltage, or ideal sine wave? None posted. Because both 'cleanest' and 'dirtiest' power have spikes, noise, and ripple voltages. Because no pure sine waves exists even in 'cleanest' power. Every honest answer is tempered by numbers. Techtarget.com has no numbers. You should have immediately rejected it as something equivalent to a lie.

None of those devices acted like a fuse. UPSes, line conditioners, and surge protectors have existed long before you, I, or PCs existed. Best UPS is already in every laptop. Power loss does not damage electronics. Protection from anomalies that can overwhelm that existing superior protection must be at the service entrance. With a low impedance (ie less than 10 foot) connection to single point earth ground. See a number - ie 10 foot? Honest replies provide perspective - numbers. How many joules does that Cyberpower or APC claim to absorb? Why are numbers adjacent to every mention of those products? Spec numbers must be provided to have or demonstrate a minimally sufficient answer.

Do bulbs dim to or approaching 50% intensity? If yes, then a serious human safety issue may exist with defective wiring. No air dryer or refrigerator should cause that. Stop trying to cure symptoms. Instead, fix a defect that is even potentially problematic to that hairdryer and refrigerator.

 

[winterquilt]

From your reply you make it sound like UPS units provide no hardware protection what so ever in practical day to day use. I need to worry about the software side as well as hardware, I've stated that several times already, obviously I expected to be able to do both. I assume then that all a UPS could do would be to give me time to shut my computer down, which is important, software wise.

You rage about a lack of numbers, but I gave you my numbers, and those of the UPS I was considering, I don't know what other numbers you're referring to?

I would like to catch the manufacturers out, if you're an engineer then please give me a question to which they cannot answer, I don't have enough knowledge to do it myself and I think people should know about their bogus claims.

 

[westom]

You rage about a lack of numbers, but I gave you my numbers, and those of the UPS I was considering, I don't know what other numbers you're referring to?

Power consumption obviously says nothing about hardware protection.

Extra Low Voltage is about protecting humans; not protecting hardware. Defined as "a low risk of dangerous electrical shock".

Spec numbers for hardware protection define 'absorbing' or 'blocking' a transient. Obviously numbers for VA, Amp-Hours, battery voltage, and watts do not define hardware protection.

If a UPS does protection, then numbers define joules that are 'blocked' or 'absorbed'. Specifications that list joules numbers are often found under a heading of Surge Protection.

Previous post defined this. "How do hundreds of joules in a protector or conditioner 'absorb' a surge that is hundreds of thousands of joules?" And "Protection means one says where hundreds of thousands of joules dissipate."

What are numbers for each UPS? That one spec of 405 joules means it will absorb 135 joules and not more than 270 joules. Obviously no where near to 'hundreds of thousands of joules'.

 

[winterquilt]

I am going to go through every point that I know in order to better understand what a UPS can and can't do, but it will take time and I'd like your input.

Lightning: I live in London, in a residential area, it's fairly flat and other surrounding objects would likely take a bolt of lightning before our house would be singled out, so the chances of a direct hit are fairly remote. We also do not receive a lot of lightning or thunder, especially now in the autumn period. We also, to my knowledge, do not have a whole house surge protector.

However, if a bolt of lightning were to strike and it affect our house then it would likely be at the transformer which supplies power to our house, however, this event is further reduced as cabling is underground. A single bolt of lightning can contain millions of Joules, and following the path of least resistance, utilising steel framework, plumbing internal cabling side flashes alone will jump any distance to get to ground.

Ohm's law describes how the current will not just follow a single direct path, but distribute itself across all paths to ground depending on each path's resistance. Even if we did have a home surge protection system, a bolt of lightning peaks at 100,000 Amperes, so even if 0.1% of that (100amps) were to evade the protection system and flow on to electrical wiring it would likely destroy anything it came into contact with (as well as burning the house down!). Even companies and residences that employ ground rods and conductor cables can suffer overflow discharges, so a UPS will not help in this scenario.

In which case, an off site backup would be the only solution.

That's lightning, next I'll look into something else.

 

[westom]

First, lightning is only one example of so many anomalies called surges. Created even by linemen errors, stray cars, and grid switching. We discuss surges in terms of lightning that is so typical of destructive surges. To avert damage from all surges, then discuss lightning as the typical example.

Second, most in the UK do not have 'whole house' protectors because UK has least surges. Why would anyone spend £20 per appliance for a near zero plug-in protector? Why not spend £1 per protected appliance for something that actually protects from all typically destructive surges? If you do not need a 'whole house' protector, then you do not need any protector. Definitely do not need even tinier protection in a UPS. Since that plug-in protector and UPS also need protection, then either properly earth one 'whole house' protector. Or spend no money on near zero protectors ... so that superior protection already inside every appliance is not overwhelmed.

Yes, adjacent protectors can even compromise better protection inside some appliances - as we proved at the semiconductor design level complete with a design review.

Third, Ohms law for resistance or Ohm's law for impedance? Big difference. You also assumed linear resistance. Surge protection is about non-linear events. Your assumption of 'distributed' currents is valid for a linear circuit. Even transformers can make surge damage worse when protection in that protection layer is missing. All examples of assuming a linear circuit rather than what is a non-linear event. Even electrical properties of a gas verses plasma must be considered.

Fourth, your examples of 100,000 amps and 100 amps is flawed for many reasons including what Ben Franklin demonstrated in 1752. Meanwhile, a 100 amp surge is trivial. For example, how many surge amps can a 1 mm dia (18 AWG) copper wire conduct? Something less than 50,000 amps. That same wire is also rated for 10 amp continuous service. No contradiction exists. Learn why all numbers are consistent and accurate - meaning basic electrical knowledge is required.

A 100 amp surge is easily averted by any properly designed protection. 'Whole house' protector is properly earthed to even make direct lightning strikes (ie 20,000 amps) over many decades irrelevant. That 50,000 amp specification numbers means an effective protector remains functional for decades after multiple direct lightning strikes. In environments far more challenging than London.

And again, the critical expression in that paragraph, as usual, is not 'protector'. It is 'earth ground'.

Fifth, transformers can actually make damage from lightning worse - not always provide protection as only assumed. That was summarized in a 7th and 8th paragraph in post 30 in this Canadian forum:
https://forum.canadianwoodworking.c...-protection-after-tonight?p=831534#post831534

Best is to read that and many following posts (multiple following pages) for so many facts so little known when plug-in protectors are recommended. Facts that include plenty of perspective, experience, and numbers. Then more accurate and relevant questions might be answered here.