DIY Home EV Charger
jamesfotherby.com
jamesfotherby.com
I currently also did my own DIY EVSE charger mainly for fun [1].
If you are interested about the main differences between your approach and mine:
(1) I use an industrial contactor DIN form factor for the power switch instead of passing the power through the relay directly. Mainly for safety reasons (I do not trust much small relays) and also because I wanted to support three-phase power for an European T2 installation.
(2) Instead of printing my own PCB with an Arduino for the PWN, I just bought one command module from China/UK provider. Mainly for pure lazyness reason :) The module itself is shield behind the RCD class B.
(3) I have added a shelly 3EM front of the system. To use it as a watt-meter with MQTT report and also as a remote control system.
My little advice for people interested to do their own: DIY is always an excellent way to learn and if you want to do your own, do it... BUT please make your installation reviewed by someone with an electrical engineering or technician background if possible. These systems can easily pump 7 to 22KW during extended period of time: Any cable which is not screwed properly or under-sized can bring you a fire.
[1]: https://github.com/adevress/open-ev-station/blob/master/READ...
£900 is $1140. In southern California, it cost me $750 for top notch work and hardware, including: $400 to have an electrician install a 240V 50A outdoor outlet (NEMA 14-50), plus $350 for a good quality level 2 40A EVSE (this one: https://www.amazon.com/dp/B082LMVSLY) that I installed myself as it simply plugs in the outlet and it's just a 5-minute job to secure it to the wall with two screws.
It's possible to bring the cost down to around $600 when picking a cheaper EVSE (like https://www.amazon.com/dp/B08LMX4TJR?th=1), so about half the UK cost as reported in the blog post. I would love to see a breakdown of that £900... that seems really high.
The £900 will include: supply of a 7kW EVSE; adding a new circuit to your consumer unit/fuse box; running a few tens of meters of fairly expensive cable (6mm SWA suitable for outdoor and underground use) in a careful, tidy way; adding an extra ground point, if needed; an electrical safety test with a special tester; and issuing a certificate (which is mandatory for this type of installation). It'll take the electrician about a day.
People in the UK pay a fairly hefty premium as we don't have as many qualified installers as we probably ought to.
Of course, standard British sockets already supply 3kW - so the cheaper option is just to get an outdoor socket installed on an existing ring main. This is substantially quicker to install in most cases.
From my searching, this doesn't meet the current regulations of the socket is intended for EV use. The costs to make it compliant bring it up to the better options anyway.
And of course, you'd fit a socket like [1] which is waterproof even when in use, and has a built-in RCD if your consumer unit doesn't have one. It's common sense when using electricity outside. And your installer will want to make sure the circuit has enough capacity to avoid nuisance trips - put your EV on the same circuit as your kettle, washing machine, dish washer and tumble dryer and you'll have a frustrating time :)
But my point is, not every Brit with an EV spends £900 on EVSE - especially if they're only commuting two days a week, or they've got a plug-in hybrid.
[1] https://www.screwfix.com/p/masterplug-ip66-13a-1-gang-weathe...
No, not any more.
I ended up installing one myself, but spent almost as much anyway. 800 euro for an Alfen Eve charging point with support for OCCP protocol (for reimbursement of electricity cost by employer), about 200 euros in other materials (admittedly with some scope creep), 150 euros for the mandatory technical inspection...
Without doing some of the installation work myself, the electrician would have cost me several hundred CHF more.
Also, the £900 includes 20% tax.
Is it a case of using a high quality socket which costs 2-3 times as much?
The electrician may have been referring to the 16 amp connector specifically being too close to the charging current.
We have an EV and a PHEV, I had a charger installed back when government grants were much more generous, we paid £250 to have one installed, but nowadays I think I'd just make do with a 3 pin charger, or get a commando socket installed + OHME 32amp commando socket charger, much cheaper than this.
Why? I was on Octopus Go for a long time, I'd just set the in-car timer to charge between 00:30 and 04:30, worked fine even with a 3-pin charger. It won't work with Intelligent Octopus, but it's by no means the only way to get cheap electricity.
Not that it matters anyway, I kept a detailed log of our usage for months and concluded that GO wasn't actually saving us any money, the cheaper electricity at night didn't offset the energy used during the day, not at the idiotic prices they charged for peak usage anyway. We just switched to Octopus Tracker, I can charge my car at any point during the day and it's actually cheaper than being on GO.
Intelligent Go is saving me a lot. But the peak rate where I am (I believe it varies by region) is only a few pence more than the cap. And I'm trying to use washing machine etc only off-peak where possible. My bill is now less compared to before I had the EV.
And yes I was always scheduling the washing machine and dishwasher for the cheap hours at night, but we both work from home, both run a lot of equipment, the daytime cost just was destroying any savings made during the night. But again, that's just us and our situation.
Looks very similar to OpenEVSE but he wrote his own code.
Nice clean build. Not sure why the extra work instead of just downloading OpenEVSE.
But without some kind of a cost difference, I'd probably stick with something like OpenEVS, which seems to have some level of official certification [0].
I personally regret my decision to not go with them when I got my EVSE this year. I went with an EnelX Juicenet because A) it was on the list of devices my power company would mostly pay for and B) at the time it had API availability to integrate with HomeAssistant. They have since killed that second part, which I would have loved to still have. In the long term, the ~$500 I saved by having my power company reimburse was probably not worth the lack of control I now have.
[0] https://openev.freshdesk.com/support/solutions/articles/6000...
-edit- He does have a total cost, I just missed it: he claims that it was ~£200. I leave it up to the reader if that's enough savings to give up the certification.
When OpenEVSE was new, I built one on perfboard, actually a very compact modular stack of perfboards, one layer per subsystem. Handed it off to my software-savvy friend, and he couldn't get it to pass self-test, despite both of us agreeing that every piece of the circuit appeared correct as per the published schematic.
Eventually he gave up and ordered one of OpenEVSE's commercially-produced boards, and it failed self-test at the exact same place. Apparently there was some unclear documentation and it was supposed to fail there until something else was hooked up, I don't remember the details, but there was nothing wrong with my stack of perf in the first place. Argh.
All of which is to say, it's not hard at all to build one of these things. if you want to lobotomize your closed-crap EVSE and lash an open board to it, do so! I'm pretty sure the JuiceBox is OpenEVSE-based in the first place so it might be as simple as reflashing some firmware.
[0]https://www.theverge.com/23949612/chamberlain-myq-smart-gara...
After reading this article, I had been considering getting one of their most basic kits that doesn't include the cables from the wall to the box or the box to the car (since I have both of those with my current EVSE), but if I can get the same functionality reusing even more of my current one, that would be ideal.
EVSEs also manage DC charging in commercial settings, which bypasses part of the charging hardware in some cars.
My Porsche Taycan is available with multiple chargers from the factory. I have the faster AC charger unit and there is a third unit that is only sold in Europe for Type 2 chargers. The actual charger handles converting AC to DC, which is car specific and why it’s not in the EVSE.
Thank you, I wasn't previously aware of this distinction.
So for simple units that are just "a fancy plug and contactor" (no balancing, limiting, V2G, V1G, etc), what do we call them? I know not to say "EVSE" now, but what should I use? Thanks again.
For level 1 and 2 charging, the charger is in the car. J1772 ports are basically just fancy 110v or 220v AC plugs with some extra signalling.
DC charging tends to happen at much higher power levels, and that equipment is expensive so the AC-DC converter is kept outside of the car. The car itself just has a couple contactors (i.e. high power relays) to connect the charge port directly to the battery, and a microcontroller to tell the charger how much current it can handle at what voltage.
The general public does not know or care about the distinction and in the grand scheme of things, it doesn't matter.
I think "charging station" is the least confusing term for the fixed infrastructure part. If regular people call those "chargers" in non-technical conversation, then I'm not going to lose sleep over it.
And depending on the sophistication of the phone, that converter outside the phone might be doing most of the work.
Well yeah, they are being silly - I don't know why that would be the distinction, even if it did AC-DC conversion it would have no idea what the battery is doing which is the entire point.
>>that converter outside the phone might be doing most of the work.
Maybe, but usually the circuit that controls and monitors the battery is inside the phone, not in the "charger" outside. Even battery chargers for power tools and such work this way - the circuit that controls the battery charging is actually inside the battery pack not in the base, but everyone would call the base a "charger".
The AC power passes straight through the EVSE, unaltered in voltage, current, or waveform. The EVSE may monitor the current to perform logging, and the EVSE is required to monitor the AC imbalance like any other RCD/GFCI does so it can open the contactor if there's a ground fault, but that's it. It's just a smart extension cord, basically.
The charger is in the car, and is the component that actually converts the AC from the grid to DC for the batteries. The charger is what has all the silicon (or these days, probably gallium nitride?), and the inductors and capacitors and stuff to actually transform the power from one form to another. It changes the voltage to match whatever the battery needs at the moment. It controls its own DC output to match the battery's needs, and it limits its own AC input according to the signal from the EVSE so it doesn't trip the upstream breaker.
The charger is also responsible for immediately turning itself off, reducing its input draw to zero, within a few milliseconds of someone pressing the latch of the EVSE connector handle. This indicates they're about to pull it out, and the contacts aren't designed to handle arcing, so the charger is required to drop its current _very_ quickly, allowing the contacts to be separated without creating an arc. That signal (called PP) is produced in the handle itself, there's just a tiny switch underneath the latch. The handle is technically part of the cord which is technically part of the EVSE, but the EVSE has no responsibilities related to the signal, that's all on the charger.
If the SAE hadn't mandated that the EVSE perform RCD functions, it could be replaced by a literal extension cord. Many small DIY EVs do precisely that; the charge cord is the exact same one you'd use to run any appliance. It works just fine. But even small DIY EVs have a real charger too, which converts the AC from the cord to DC for the batteries. The charger plugs into the cord, but the charger is not the cord.
Because you'd need to use a word like "plug" or something, not because of whether it's "charger" specifically.
All you need then is a breaker, dryer outlet, and some thick gauge wire between the two.
We hope. I don't trust anything being sold on Amazon or any other such website known for scams, knockoffs, and otherwise shite products being passed for legit. I'm less concerned about the price of the components vs the quality of the components. You can have cheap quality but a high price just to fool people that expensive is good.
As with the misnomers about the "charger" terminology, I could appreciate a layperson getting this confused.
$40 HDMI cables are an option (albeit a terrible one). For EVSEs, there really isn't a reasonably-priced alternative on the market right now.
Just some things to keep in mind
* BoM - Bill of Materials (“what stuff goes into this thing?”)
I’ll often find something on Amazon and if it seems like it’s from a small business, I’ll check to see if I can buy it direct. (Arguably, this behavior is unethical on my part against Amazon, but whatever.)
I very rarely (like <10% of the time) find the first-party site to have an offer that even matches Amazon’s.
Look, I tried. I came to you and gave you a shot, but if you want to charge the same item price and also tack on $15 of shipping, I’ve received your message (“please buy it from Amazon; we don’t want to sell it to you direct…”) loud and clear.
I’m usually willing to wait a few extra days, pay the same price, and have worse returns possibility in order for you to double or triple your variable transaction profit, but you’ve got to be competitive.
Advertising on Amazon is nearly, but not quite, a requirement in the current marketplace.
This has been part of the recent antitrust action against them.
The hassle of inventory/shipping logistics is something people with no experience easily do not consider.
According to whom? The people who think going to the bathroom during a TV commercial break is "stealing"?
Since when is comparison-shopping unethical?
I do think “thank you for letting me know this product exists and meets my need, but if all else is equal to me, I’ll buy it somewhere else where you don’t benefit from the effort to help me address my need” is not the standard that I hold myself to generally.
Further, I think many would object if I found a product through a small business directly and bought it for the identical terms via Amazon rather than direct.
It could drop at any time due to, for example, many chargers being connected to 1 circuit and the chargers coordinating with each-other to load-balance their connected vehicles (everyone gets their fair share), or it could be tied to solar PV generation so that charging doesn't import from the grid; the available current will change with how much excess PV is available, etc.
A well-engineered EVSE will notice when the EV is drawing more than the EVSE wants it to. It should then open the mains contactor at this point; cutting the EV's electricity supply. It will also hold the control pilot low to signal a fault to the EV.
Not saying this is the case here, of course, but they could do something similar that way if they wanted to...
If the AC "charger" attempted to regulate current by varying voltage the actual onboard charger would just attempt to pull more current to make up for the voltage drop and probably trip the whole thing.
There would be no point in regulating the AC current, it would make the charger very complicated and expensive replicating much of whats in the DC converter/charger in the car.
A full DC charger like at a charging station does do this because it is the actual charger bypassing the cars small internal DC charger with DC leads going directly to battery at full pack voltage.
I do intend to add a second sometime, so that I can put the EVSE in my home automation UI as well; the version 2 of smartevse that I use does not have a network connection, but it can be connected to be controlled by a version 3 that does.
The box in that guy's build is outside and could probably burn to a crisp without hurting anything else. I suspect it would not hurt anything even inside a garage, other than making a lot of smoke and setting off smoke detectors.
It's surprising that we have such cavalier attitudes when it comes to our own field, but so much fear and magical thinking about the power of government oversight when it comes to everything else...
You must be new to HN. Let me introduce you to the two types of comments:
1) The problem I am responding to does not involve software. The people in that industry must not be competent. Therefore, the solution is more government regulation.
2) The problem I am responding to involves software. Everyone in my industry is highly competent and moral! Therefore, let the free markets operate and the problem will automatically disappear.
Just no? That analogy is EXTREMELY strained. From his own link: A word about safety. I’m not an electrician. I’m not allowed to make alterations to my consumer unit.
I let my kids play outside all the time solo and with friends without supervision. On the flip side, I don't do things like design my own L2 charger because it violates several codes, would nullify my homeowners insurance, and could quite literally land me in prison should I mess it up and cause a licensed electrician to die because I did something dumb or cause my car to start on fire killing my family.
Do I do my own wiring? Absolutely.
Would I mess around with attaching something at 240v that I made from scratch that could burn my house down and kill my family if I do it wrong? Nope, I'm good.
It's funny how we reach a society where you need government as a babysitter and tell what you can do and whatnot.
> Would I mess around with attaching something at 240v that I made from scratch that could burn my house down and kill my family
It's also funny how those people readily plug in any consumer device they buy on amazon, which is assembled in china/india without any thought about safety.
every code regulation is written is blood. the inconvenience is designed to prevent people burning their house down or worse.
Every code regulation is written because some forces lobbied it. It’s nice to think those forces care about you and me, but it’s also incredibly naive.
It almost certainly wouldn't.
Generally speaking, in the United States, homeowners insurance "covers stupid".
DIY electrical wiring, and the like, would be covered unless something was intentionally or maliciously negligent.
If you miswire a three-way lightswitch (in good faith) and (somehow) burn your house down, that is generally covered.
What is up with this common refrain? One of the main functions of insurance is to indemnify you against your own negligence. Let's say you turn a small stovetop fire into a house fire by trying to put it out with water - the insurance company doesn't just get to stiff you because you were responsible for causing the problem. Are there actually prevalent and enforceable weasel clauses about DIY work in some areas, or is this a scare story popularized by oversocialized redditors fantasizing about what might happen, or what?
Also then, a different example: You plug in a non-NRTL-tested appliance from Amazon, and it burns down your house. Clearly outside the bounds of what is prudent, but also something many people commonly do. You're telling me that insurance is set up to stiff all of them, and yet we're not seeing endless news articles about that happening?
As an aside- do cheap electronics actually burn a lot of houses down, or is that scare mongering? I half remember reading that it was large white goods like dishwashers and washing machines that actually started most fires, and they are not typically bought on Amazon or only on price.
And if you think about it, such an exclusion would be crazy. The average homeowner is in no position to judge whether the work someone they hired does exceeds the scope of their license, or whether all the details of the work that need a permit get one, or whether work any work that doesn't get inspected is in fact done to code. Furthermore, the average homeowner isn't the original owner of their house, and is in no position to know what tomfoolery the prior owner might have done.
For those of you out there that are certain that DIY electrical work voids your homeowners insurance, can you prove any evidence to support your claim? A local news story about a guy whose homeowners insurance denied him because he DIY'ed something in good faith? A FAQ page from an insurer that says that DIY'ing something voids the insurance? Anything other than a vague reference to there being a lot of words in your policy and it gets interpreted through the lens of an enormous body of caselaw and the insurance company can afford more lawyers than you?
Insurance regularly pays out when people do stupid stuff and cause a loss to their own insured property, as long as they weren't trying to do damage. Doing stupid stuff that happens to involve electricity doesn't seem any different to me. And frankly, building your own L2 charger after much research and thinking about the safety aspects seems like a far cry from a "here hold my beer" moment.
An intentional or reckless act wouldn't be insured if it directly causes a loss, but anything else is. There's no exclusion for doing things that are illegal other than illegal substance manufacturing, and I'm pretty sure I didn't miss anything because the whole policy is 12 pages, including the cover and table of contents.
Electricity regulations wise, it's legal for me to do anything that plugs in to a socket. If I owned and occupied the property it's legal to do anything that doesn't require moving or adding a fixed cable to the consumer unit. Adding new fixed cable runs required a licensed electrician to sign them off before energising. It's illegal to do DIY electrical work on a property if it's let to anyone other than family, unless it's certified by a licensed electrician.
It's reality? Installing an L2 charger requires a permit. You don't technically have to get one, there's no county police that goes door to door checking for improper/horrible EV charging installations. However, if your house burns down, and they see you decided to jury rig your own charger from piece parts, I can guarantee you with 100% confidence they're going to tell you to pound sand when you make an insurance claim.
On the off chance your home-made charger didn't start the fire, you can spend a decade fighting them in court. But you'll probably lose.
Anyway, how many DIY EVSEs start fires? It's a glorified extension cord, not exactly rocket science, and as long as the builder applies a modicum of sense to choosing the components and wire gauges inside, and torques the connectors and stuff, there's really not much going on in there that should produce heat in the first place.
Also, this isn't a charger. It's an EVSE, there's no power electronics inside. There's a contactor, that's it, no silicon in the power path. It's really hard to screw it up.
Perhaps I'm just accustomed to the Hackaday comment section, but HN commenters are weirdly terrified of anything involving AC. It's just electricity. Not even very much of it, like, normal household levels of 240v AC. My clothes dryer uses more power, and it pulls it over wiring installed in the 1970's. Heck, when I moved, I even replaced the cord on my own dryer with one that matches the outlet in this house, an action explicitly allowed and encouraged by the access plate on the back of the appliance. The bare cords are sold at Home Depot and they come with a little slip of paper explaining how any homeowner can install them.
It's fine. It's just wire. Pick one that's thick enough, torque the screws, it's fine.
So two funny things about this in UK law - the law doesn't say who is allowed to work on your consumer unit, you can do it by yourself if you wish. What the law does specify is that the work has to be certified by a "competent person" but then doesn't actually narrow down what a "competent person" means. Local regulations might, but the UK law on this does not.
There was a huge debate about this couple years ago, when someone asked "can a foreign electrician certify a UK electrical installation as safe", and after very long debate the outcome was that yes, they can, because the British regulations never actually specify what they mean by "competent" and a certified electrician(even if foreign) is definitely "competent" even if not registered with any UK based authority.
No. You can't touch the consumer unit, and there's a restricted zone around bath/shower for example (by distance), but most things a homeowner might want to do are perfectly legal to DIY.
> the US, but the UK is noticeably more safety-obsessed.
Crikey, are you joking? Internet forums are awash with US concern over 'code', and to extend beyond electricity: food safety, FDA guidelines, all sorts of common senseless rubbish.
It isn't uncommon for people to be scared when they learn I wired my home which has a 400 amp service. I wired the previous two also. Sure electricity could kill me, burn me, burn down my house, etc., but I don't have to be the one to discover how it works. People have done that and there are building codes to follow that are build upon a whole bunch of previous failures.
We all learn different things and are at different places. I can wire my whole house and pass inspection, but I'd never take on this project, that is beyond me - but more power to him for trying. I agree, nothing wrong with some DIY that at most will go up in smoke.
And I have a large number of items that either came with my house or I purchased legitimately that could absolutely burn it to the ground. It's all measured risk.
When I get an EV, I'll be adding a consumer grade charger to the house. And then I'll trust, with zero actual knowledge, that it won't burn down my house, or that my car won't.
It's also my experience that if you have the know-how, you can often do a better job than the professionals you hire, or the factory that mass-produces a product for the highest possible margins.
The leaps here are way too big.
>I'm disappointed at the anti-DIY sentiment
This is essentially the equivalent. Total insanity.
So? The system that controls the relay (with logic to prevent exposed high-voltage contacts while the car is unplugged, or danger if the cord is damaged or immersed in water) is just as safety-critical as the relay itself.
> "didn't use a GFCI or AFCI breaker where one is required, but did try to address the same safety hazard those breakers address, in a way that wasn't as good as such a breaker
Stop right there. What you describe is automatically incompetent, all by itself.
Seriously, don't do this ever. There are extremely good reasons why anything but certified, unmodified hardware is illegal to install in electrical wiring. There are equally good reasons why you can't omit required safety hardware, even if you "tried" with something else.
These laws are written in blood.
But I appreciate he didn't put this in his garage. However, even hooking it up to the CU is not something some random guy should be doing: https://www.speakev.com/threads/a-cautionary-tale-of-severe-... (this one was probably due to not-adequately tightening the terminals, would you even think/know as a DIY'er?)
Doing & making things (within reason) is the essence of human experience. Buying all the things is the essence of consumerism.
I just think it's a good principle that someone older than me shared with me a long time ago, in an electronics hobby store that no longer exists, when I was buying parts to build a bench power supply, though I had to discover some reasons the hard way.
I thought they were being an ass at the time, so I plowed ahead with my project, and realized halfway thru that this project was pretty dumb and I should have just bought one and moved on to a better more interesting project.
Yikes. Get some 5 watt resistors.
2. If it's outdoors, at least spray the electronics with Fine-L-Kote or similar to keep water vapor out.
3. Those relays look undersized for the load. Look at Grainger for similar ratings. Do not buy power relays on eBay or Alibaba. Current ratings there tend to be wildly exaggerated.
4. Er, overcurrent protection? An approved circuit breaker?
Granted the article notes it appears to be largely a resistive load, but I would want data sheets on the car/charging requirements, not measurements, to ensure this is true 100% of the time. Maybe the car has an AC compressor or a pump to cool the battery during charging, which draws directly from the charger when plugged in. You might not see that doing a few random measurements because it turns on only after some time or if someone is sitting in the car.
It turns out that the engineers who designed J1772 thought a fair amount about how to handle the connect/disconnect concerns that you raise (via the pilot signals and proximity microswitch) and they didn't just leave it to EVSE designers to YOLO it.
> I would want data sheets on the car/charging requirements, not measurements, to ensure this is true 100% of the time
The "datasheet" that you want is the J1772 standard. There are many free summaries of it, including https://openev.freshdesk.com/support/solutions/articles/6000... Scroll all the way to the bottom and read the section on "Proximity" to understand how the relays are not disconnected while large currents are flowing.
No it doesn't. A/C compressors in EVs are 3 phase AC powered by an inverter supplied by the traction battery.
The contactors in an EVSE open and close at practically zero current, the OBC ramps the current up or down accordingly. And as another sibling comment noted, the OBCs are PFC corrected and act as a largely resistive load.
This brings me to my second point: I don't see a cycle rating on those relays from the datasheet provided. Most relays are rated for ~1M cycles, some for ~10M or more, but beyond that solid-state relays start to be a thing. And so, I question if people are using mechanical relays to chop 50/60Hz AC power, which from my 30 seconds looking at the article/schematic appear to be what is happening here... That seems crazy to me, and I imagine it requires some exotic contacts in the relays to avoid failure in short order, which these relays don't appear to be. The data sheet mentions they are used for chargers/solar inverters/etc but that doesn't mean they are used at 50/60Hz cycling but likely just as a disconnect/power on function which cycles once per charge/day/etc.
Then again, I don't really want to be this guys neighbor since chopping an AC line with that much load is going to generate an insane amount of noise, and I don't see anything in the circuit designed to damp it either.
The real problem here is DIY RCD with microcontroller in the loop. The soldering on the high voltage wires is absolutely horrendous and if those come loose and the enclosure or chassis becomes live you are trusting your life on the atmel interrupt delay and software. Good luck!
Edit: it's not even an interrupt, its just part of the Arduino loop(): https://github.com/fotherja/EV_Charger/blob/main/EV_Charger....
If you're trained, experienced, and generally know what you're doing there's nothing wrong with working on high power electronics.
Congrats to OP on a clean project
source: electrical engineer who writes high performance software you’ve definitely have used
So a Show HN project that's purely software effectively is worth $0, because the creator made it in their free time, instead of spending that time playing video games or watching TV or whatever. And a Show HN project with a lot of software running on a RasPi effectively costs only what the RasPi cost the author.
Here, people are complaining about the actual hardware cost to the creator, not the creator's time spent, which you're also ignoring.
Everyone, no matter how materially wealthy they are, gets 24 hours per day. That time is, by definition, 100% of the time that you'll get, which means that its value (intrinsic) is nearly infinite. This is true even if its price (extrinsic) is zero.
My point in mentioning an engineering rate was not to quibble about what free time costs. It was to say that even if someone confuses price with value, we can agree the the value gained from time well spent is very high. So it seems strange to criticize a hardware project that had $X of "hard" costs, $Y of "soft" costs, and $Z of benefits, when we regularly admire software projects that are valued identically, except that $X is close to zero. $X + $Y + $Z = a huge net positive value (judging from the number of HN comments and votes, as well as the pride that OP shows in the writeup). For many of these Show HN posts, it doesn't matter if $X is $300 or $0; the math still evaluates to awesomeness.
I value my own free time much more highly than I do my employment time. I would prefer to have more free time than employment time. So if employment time's going rate is $X, then a dollar value of free time must be higher than $X. No, I don't expect people to pay me for my free time. But I do think it's healthy to think of free time as the most valuable time someone can have. Not the highest price but the highest value.
This is why I think it's wonderful to see projects on HN where we find out how our fellow geeks are spending their most valuable time. And it bugs me that people sometimes respond that someone could have bought the same thing for less money or less time.
Ironically, we both object to putting a price on time, but I believe our objections are in opposition to each other.
And sure, I agree that it's nice to see people spending their most valuable time doing something they enjoy, in this case interesting projects.
But as I've said elsewhere, personally, I wouldn't spend my time making a copy of something I can just buy a better version of cheaply elsewhere; if I'm going to spend my time on a project, I'd rather spend my time doing something different, like something new or a customized version of something, which I can't easily buy. But it's not black and white; I'll happily spend my time fixing my bike instead of paying someone to do it, for instance. (Of course, paying a professional might take more time once you consider how long it takes to bring the bike to them, and then wait a week for them to get to it...) I like fixing things like that, so for me it's enjoyable.
In comparison, hardware projects have costs even if the 'hard work' is done: PCBs to buy, components to assemble, parts to purchase. Even BEST case here, and discounting peoples time, it looks like the cost of all the components listed would be in the neighborhood of $200. And that assumes you can source the same 'demo' cable that the OP purchased for the same cheap price. Realistically I bet actual costs would be $300+
I have nothing against DIY hardware projects, the problem is that hardware projects must pass a much higher bar: you have to be cost competitive at a minimum with existing products on the market, or you need to be better in some way (and, that way can be trivial, as long as it's interesting). This appears to be neither.
Stuff like this is absolutely what I would consider "worth" paying a professional to do. Especially since buying a retail unit/paying a professional to install it will come with warranties.
Maybe we need a few to burn their own houses down to act as a deterrent and encourage others to stay in their lane.
I’ve installed 3x 240V 60A EV chargers, was a cakewalk. I didn’t build my own in this case since I was going for an aesthetic match.
Meanwhile you can enjoy paying some alcoholic $1000 for 30 minutes of work to:
* pop out a hole on the back
* Tap and install 2x screws into studs
* pull 3 wires 6” through, wrap around the strain relief, strip/insert/torque
* flip a breaker
It’s not rocket science, as long as you’re not a complete idiot and turn the breaker off before hand it’s completely safe. 240V isn’t even “high” voltage.
* Solar panels installed facing North in the Northern Hemisphere; rapid-shutdown switch installed inside a home; supply side of 240v connection to backyard office has male prongs; fence built with non-pressure-treated wood contacting the soil. The list goes on, and these are only the errors I've discovered in 20+ years of being a homeowner.
So in case of lightning strike (which is pretty much a given) that would invite that lightning into your home right at the distribution panel. People may be following 'the code' but that doesn't mean they actually understand what they are doing. He wouldn't take responsibility for it, I asked him to put it in writing as an instruction and sign off on it so I could pass it to my insurance company. That never happened...
And this is important for lots of reasons. If there is a fault from a hot wire to a grounded object, this (if done correctly) allows the upstream overcurrent protection to trip. And it minimizes the voltage rise of the object that gets energized. And it keeps the line-to-ground voltage within spec. And using a separate ground means that the voltage of “ground” doesn’t get pulled up by resistance in the neutral wire and that current doesn’t normally flow through “ground”.
You should, of course, also connect the ground wire to Earth, well, at the base of the structure. And possibly also install something to help conduct lightning currents from the non-ground conductors to ground in the event of a lightning strike.
That's an interesting start to your comment. So you don't know the whole setup but you do know the inspector is likely right.
Well: if he was likely right he would have not shied away from putting it in writing. What happened was that halfway into the conversation he realized he was wrong, hightailed it out of there and simply didn't want to admit that he was wrong.
I do know the whole setup. And I have spent enough time installing high stuff made out of metal (mostly: antenna masts) to know that the last thing you want is to give lightning a short path into your dwelling.
His whole experience seemed to be based on simple domestic installations, and instead of just admitting that he didn't know exactly what to do and to go look it up or ask someone more experienced to look it over he dug in. Human nature, I get it, but this is safety we're talking about and the amount of flak the OP is getting in this thread from people that likely have more experience with keyboards than with real world engineering is telling. Just like you: they don't know the whole setup but they'll argue that it is unsafe, will void your insurance, will get you investigated for arson(!) and might kill your kids.
You last paragraph is exactly the problem: he outright forbade me to ground at the base of the tower because that was in his opinion unsafe. But it wasn't his life and property that was at stake.
I've seen up close what lightning will do to various pieces of gear, it isn't pretty, to put it mildly and you make sure you keep it as far away from your house as you can. And have spark gaps to ground at the point of entry for your power cable, just in case.
Finally: the proof of the pudding is in the eating. When after a year we pulled the tower down again there was evidence of multiple strikes on the nacelle body at the top of the tower, all of which were dealt with gracefully, to the point that we didn't even realize the machine had been hit. What helped is that for the whole installation we had a massive amount of help from an experienced wind turbine vendor who took an interest in our project.
Whether you connect both grounds to both themselves and Earth, or just connect both grounds to Earth, or connect them to Earth once and connect them both depends on so many details, it's not funny.
What is certain is that you don't want something that doubles as a lightning rod protected on the same internal circuit as your house. So your rationale doesn't apply to the GP.
But anyway, every time somebody talks about electrical installations on the internet, somebody says some version of "If there is a fault from a hot wire to a grounded object, this (if done correctly) allows the upstream overcurrent protection to trip." Is it still a recommended practice on the US to rely on overcurrent protection to protect against current leakage? It's an horrible practice, as it requires several amperes of leakage before triggering.
Yes.
I don’t agree with it, personally — I think that there should be standard ground fault trip curves that are functions of circuit breaker rating such that they coordinate properly, and that they should be used at least on all circuits that extend outside of a building and really on most circuits, period. This would add costs, and it would detect and thus prevent a lot of dubious wiring practices and outright errors.
But you should still bond all your “ground wires” together so that even if these breakers fail to trip you have a degree of protection. (And breakers do fail.)
Under current NEC (the US code), when you supply a building with a feeder (i.e. from another building or similar structure), you must provide it with all the current carrying wires and separate ground, and you must ground it to the Earth.
In any case, if you live in a place where your utility supplies power above ground, and a utility pole or line is hit by lightning, its ground is most certainly solidly connected to your house. So you can’t really pretend that your house’s ground is connected only to the Earth near your house and that it won’t let lightning in.
Hmm, I wonder if you can take the ground wire running between two buildings and carefully insulate it and give it a wrap or three around a piece of steel to add some inductance and reduce lightning currents that might otherwise go through it. I’m not saying this is wise…
That + the use of metal tubing to carry electrical power as well as the incredibly flimsy construction of various sockets and such (as well as the high amperage) translates into lots of preventable fires each year in the USA and Canada. Point a FLIR at your average distribution panel and try not to be amazed at the number of hot spots.
My biggest gripe: I don't mind inspectors, I just expect them to be really knowledgeable, not just theoretical. Grounding a structure is inherently different from grounding a circuit. He basically kept on insisting that the windmill is part of the circuit and should be bonded rather than that it had its own ground and that is just patent nonsense, more so because the windmill produced variable frequency AC that first had to be rectified, passed through a battery charger, a bunch of batteries and an inverter. The latter of course was bonded to the house ground.
Outside is another matter. Those galvanized steel tubes don’t last very long underground, and the results are terrifying. And nothing in the code requires ground fault protection upstream of a 120V circuit running through a corroded steel tube underground.
A single leak also gives you a minor risk of electrocution. But the fire hazard is the important one.
The right solution is ground and arc fault protection, both of which are available, and one of which is increasingly required in the US.
And yes, they are way less dangerous if you have ground fault protection. To the point that I'm not sure it's still important to ban them. But they don't have any upside either.
Second, what’s the material difference between a 40A circuit and a 60A circuit? A few extra hours overnight to charge?
Or, as in our case, we have two EVs - speed is useful sometimes.
EDIT: Even-higher-still vehicle charging is handled by having a charger outside of the vehicle and feeding the vehicle with DC, which is what e.g. Tesla Superchargers do.
It's not difficult to do, which was GP's original point--though you need to take safety precautions (in addition to researching local code requirements).
I don’t know what advice an electrician would give, but the advice I give is that if you don’t feel like you can safely install a new circuit on a live panel, you probably just shouldn’t install new circuits.