As someone with an electrician's ticket (non-practicing, but the exam was no joke), this is a "not-so-good" idea.
A 3kW inverter powering a fridge through extension cords (fridges/compressors can have serious inrush current). You can't just snake "yolo" cables through a house for anything drawing serious amps (say, more than 5).
I'm willing to bet zero impedance or insulation/continuity tests were done. I hope the inverter has the RCD protection included.
This "works" 99.9% of the time. Now multiply 0.1% by every person who sees this and thinks it's a clever hack.
Update: He's plugging an extension cord directly into the inverter's output terminals? A 3kW inverter at 120V can push 25A continuously (and likely no RCD in the path). That can melt a 10/15A cord. The inverter's own breaker (say, 30/40A) is there to protect the inverter, not the cord. The cord may "become" the fuse long before the breaker trips on an overload (it doesn't trip at 30A instantly, more like at 100-200A if it's equivalent to EU class B/C).
Update2: I'm against overregulation and panicing at every perceived threat, but I must say, I wouldn't mind an inspection taking a look for the sake of neighbors.
Update3: The PDF (https://cdn.shopify.com/s/files/1/0746/0415/1079/files/POW-L...) says that the AC input "maximum bypass overload current" is 40A. If he plugs the inverter into a wall outlet for charging/bypass, it will let his appliances pull 40A through a standard 15A socket. The main apartment panel will eventually trip, hopefully.
This can be done safely if you know how to compute the correct wire gauge for the distance, and don't overload the circuit. You can easily and safely run 15A via a proper-gauge extension cord from a 3kW inverter to a fridge or any number of other individual appliances at once.
Where this is potentially going to cause trouble is people who don't understand how electricity works, or that different wire gauges exist, or how many watts various appliances use. The kind of person who takes a tiny lamp extension cord and plugs a power strip into it, thinking that more sockets will provide unlimited power.
The photos in this article are scary. A 2500W power strip with a bunch of crap plugged in? Exactly the kind of scenario you don't want to see. And talking about running a fricken induction cooktop off that, along with a fridge? The photo and text imply that you have near-unlimited power.
> This can be done safely if you know how to compute the correct wire gauge for the distance, and don't overload the circuit.
Agreed, a long run adds so much impedance that during a short circuit, the breaker won't trip instantly. It will just sit there and let the fault current cook the wires.
Various jurisdictions require a fault loop impedance test for installations (and discussed one looks "fixed"). This cannot be eyeballed from a wire diameter table, must be measured.
It depends on the length of the extension cord, construction, and gauge.
10awg single conductor THHN can handle 50 amps but when it's in NM-b (house wire/romex) it's 30 amps.
Extension cords can get really hot as they often have the conductor insulation, some packaging material for support, and the outer coating. It also greatly matters if it's 10ft vs 100ft due to resistance.
I've seen extension cords that were used for ACs melt carpets
It's interesting how much 'move fast and break things lightweight hacker spirit' when it's applied to stuff you actually know about turns out to be actually just be an ethos of churning out really poorly designed systems that disregard the mountain of best practices that are very well known.
It's enough to make one suspicious of the whole attitude ...
Moving fast is fine when you’re building a prototype. Having to double check everything when you are spiking an idea slows you down too much.
But once you get something going, go back, apply all your learning (because you will have learned a lot), and do a little cleanup. Especially if it’s your own personal DIY project.
Cleanup does take some time so budget it in.
My first solar project initially looked like a mess of wires like OP’s, although confined to my workbench. But after I got it working, I calculated all wire gauges, put fuses and breakers everywhere, and put the right type of wires in the right type of conduits. As it had to transit a living space, I also made it look nice — you didn’t see a single bare wire anywhere — definitely no 2/0 cable running up a wall.
What I've discovered in nearly three decades of working in various aspects of IT: any useful prototype/proof of concept system will become a production system if you do not take specific measures from the outset to prevent that from happening.
Meanwhile - the person who knew what they were doing would design the whole thing to be safe, code compliant, and efficient from the beginning, skipping the 'making it up as I go' phase.
There is this common pattern with a certain kind of HN user of not bothering to learn about something before assuming you are way smarter than any other human who has ever lived and just doing it yourself from base principles, before inevitably finding out what everyone else already knew.
If it was just diy projects it would be one thing, but entire companies are run on this principle.
I recall a WWII sabotage manual that recommends it as a very effective sabotage technique: “let relevant authorities handle it”. Then everyone waits as the relevant authorities have being inquired through proper channels.
You can’t even hire a competent person unless you have a bit of expertise yourself. You wouldn’t know the difference.
Very well said. Reminds me of the old adage about /r/crypto “a place where people who don’t believe in financial regulations learn why financial regulations exist”
"Move fast" thing applies to lots of software because most software belongs to "fundamentally safe" class of things, along butter knives and clay sculptures. People might temporarily experience sadness if they were served a mangled butter knife or saw your sand castle collapse, but they shouldn't be hurt. You don't even have to have heard of the word "functional safety" to be safe with those. Your creation is going to be default safe and perpetually safe so let them crash and burn, is the idea.
If you were writing pieces of self driving code or were building a wooden chair for yourself to sit on, that change up things a bit. The most fundamental distinction isn't in whether it's hardware or software, but whether it's safe or not.
And it only works for things that no one truly needs. If Facebook disappeared tomorrow, we’d all be better off. If the software that runs the electrical grid disappeared, it’s a different story.
> The inverter's own breaker (say, 30/40A) is there to protect the inverter, not the cord.
I have a similar "all in one" inverter for camping, and since you seem to know what you are saying: In my setup I wired a 20A GFCI outlet to my output, and use that as my main output protection. What do you think about that?
Your receptacle (20A in your case, but regardless) is not a current limiter.
The 20A is not being "enforced" in any way and your outlet can receive, and pass on, any arbitrary current ... until something melts, that is.
You could achieve your goal by wiring in a fuse, or circuit breaker in that circuit and could probably nicely (and safely) package it up in a plastic junction box, etc.
Then again, I'm not certified for solar installations - but standard <1kV home installations and measurements. (As an anecdote, there's a specialty called 'electrical installations for hydrolysis of water' - I shall get certified in that one day just for fun.)
Buy a customer-oriented device instead, if you can. I vaguely remember there are plenty of them on the market with built-in batteries. They should have RCD/GFCI and overcurrent protection (and thermal, and BMS included) per outlet (or per bus).
If you want to stick with your current inverter, here are some thoughts from first principles:
- ground it while using, but this might be hard at a remote camping site (maybe use a grounding rod?). If it's a similar model to the one in the article, it must be grounded.
- a GFCI/RCD rated for 30mA or less with 15-20A circuit breaker (I'd suggest type-A if in EU) that matches your wiring and outlets.
There should be ready-to-go boxes that provide RCD+OC, and maybe you're already using one.
Short answer - treat it as Class I (it has a PE terminal)
Longer:
A Class I inverter/appliance relies on PE. A single insulation fault (live -> chassis) will put the chassis at line potential if PE isn’t connected.
If you run other Class-I loads (eg. fridges) downstream of a GFCI but don’t carry PE, a hot-to-chassis fault on the load won’t reliably trip anything until there’s a return path (often a person).
> A single insulation fault (live -> chassis) will put the chassis at line potential if PE isn’t connected.
As long as the other wire is not connected to ground, chassis being connected to one doesn't pose much risk.
Grounding either wire makes whole thing worse. If you ground the chassis and it's not connected to either wire it makes no difference. Once insulation on any of the wires fails and the wire connects with the chassis it becomes the neutral and ground at the same time and the other wire will shock you through ground even if you don't touch the chassis at that time.
I'm curious if GFCI would trip if you didn't have the whole thing grounded and just touched one of the wires...
I know that in normal setup GFCI detects if too little electricity goes back through neutral relative to how much goes through hot wire. Assuming nothing is grounded, would short, small leakage current when you touch one of the wires be enough to trip GFCI?
Does GFCI work both ways? If there was more current "comming back in" on the neutral than goes out on the hot would GFCI trip as well? Are the usual solutions worthless when you have just two free floating wires with potential difference between them but with no reference to ground?
Is there a code for high voltage mobile installations? It seems that EV and mobile home makers go mostly with their own solutions derived from first principles...
Well, not line-to-neutral overcurrent - which is what the person asking assumed it did.
It specifically protects against ground-path overcurrent (not ground line overcurrent - it is guarding against an undesigned path to ground, which is probably a person).
Setting 11 which default to 30A with no detail in this manual, from my experience there will be something like 2A 10A 20A 30A when you cycle the option 11 values.
> A 3kW inverter powering a fridge through extension cords (fridges/compressors can have serious inrush current). You can't just snake "yolo" cables through a house for anything drawing serious amps (say, more than 5).
Definitely on his fridge, but many newer ones are inverter drive themselves and effectively soft-start. Just 100w or whatever around the clock.
Maybe in 50 years they’ll relax my local electric code and stop requiring them to be on their own circuit. Or at least tie them with lighting so I’ll know at 8PM if the fridge has gone out for the night because the 50w of LEDs on the same branch don’t work.
The inrush curent of a fridge lasts so short it's not gonna melt anything. Things melt because of short or long running overload (relatively long, could be less than a minute, but still much longer than fridge start).
Everything you wrote is correct. And the problem the author of the original post is addressing has a very simple solution: you and your bosses should eat less and live more modestly. Your medieval cable-bolt-fitters' guild should become less exclusive and demand less money for membership. The ultimate beneficiaries of horribly expensive electricity can easily live without three ranches and two yachts. And then people won't be forced to build this cable-flipping sham.
The same applies to the rest of the construction industry in the US. If they're building houses out of cardboard and sticks, they should be paid enough to buy a cardboard steak. And house prices should be low, not like they are now.
A 3kW inverter powering a fridge through extension cords (fridges/compressors can have serious inrush current). You can't just snake "yolo" cables through a house for anything drawing serious amps (say, more than 5).
I'm willing to bet zero impedance or insulation/continuity tests were done. I hope the inverter has the RCD protection included.
This "works" 99.9% of the time. Now multiply 0.1% by every person who sees this and thinks it's a clever hack.
Update: He's plugging an extension cord directly into the inverter's output terminals? A 3kW inverter at 120V can push 25A continuously (and likely no RCD in the path). That can melt a 10/15A cord. The inverter's own breaker (say, 30/40A) is there to protect the inverter, not the cord. The cord may "become" the fuse long before the breaker trips on an overload (it doesn't trip at 30A instantly, more like at 100-200A if it's equivalent to EU class B/C).
Update2: I'm against overregulation and panicing at every perceived threat, but I must say, I wouldn't mind an inspection taking a look for the sake of neighbors.
Update3: The PDF (https://cdn.shopify.com/s/files/1/0746/0415/1079/files/POW-L...) says that the AC input "maximum bypass overload current" is 40A. If he plugs the inverter into a wall outlet for charging/bypass, it will let his appliances pull 40A through a standard 15A socket. The main apartment panel will eventually trip, hopefully.