7 ms·

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 exte

by jagrsw 1y ago

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-LVM3K-24V-H_User_Manual_V1.3.0929.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.

caymanjim 1y ago
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.
- jagrsw 1y ago
  > 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.
- Braxton1980 1y ago
  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
idiotsecant 1y ago
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 ...
- jenders 1y ago
  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”
  - kimos 1y ago
    A place where you can watch people slowly reinvent the existing financial system.
- BoredPositron 1y ago
  move fast and break things was always a software mantra.
  - adriand 1y ago
    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.
  - okanat 1y ago
    There is a reason we still run COBOL systems, and it is nothing but the opposite of that mantra. Move fast and break things has only been a VC-backed company thing.
- harrall 1y ago
  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. You could also look at it as craftsmanship.
guerby 1y ago
This kind of inverter usually have a setting to limit the current they can draw from the grid. From the manual of this particular model: https://cdn-files.myshopline.com/file/store/1675916196960/ANJ-3KW-24V-LV-WIFI.pdf https://cdn-files.myshopline.com/file/store/1675916196960/AN... 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.
Scoundreller 1y ago
> 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.
novaleaf 1y ago
> 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? PS: op took down their page. archive link is here: https://web.archive.org/web/20251005022124/https://sunboxlabs.com/ https://web.archive.org/web/20251005022124/https://sunboxlab...
- a_mechanic 1y ago
  Not the person you are replying to, but a GFCI does not protect against overcurrent.
  - novaleaf 1y ago
    thanks, I'll put a breaker in-line.
  - IAmBroom 1y ago
    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).
- rsync 1y ago
  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.
- jagrsw 1y ago
  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.
whatevaa 1y ago
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).
- eternityforest 1y ago
  Unless there's a fault with the fridge of some sort.
- IAmBroom 1y ago
  The duration is not the issue; gross energy size is the issue. The inrush is probably longer than a lightning strike...
t917910 1y ago
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.
deleted 1y ago
[deleted]

by jagrsw 1y ago

caymanjim 1y ago

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.

jagrsw 1y ago
> 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.
Braxton1980 1y ago
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

idiotsecant 1y ago

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 ...

jenders 1y ago
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”
- kimos 1y ago
  A place where you can watch people slowly reinvent the existing financial system.
BoredPositron 1y ago
move fast and break things was always a software mantra.
- adriand 1y ago
  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.
- okanat 1y ago
  There is a reason we still run COBOL systems, and it is nothing but the opposite of that mantra. Move fast and break things has only been a VC-backed company thing.
harrall 1y ago
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. You could also look at it as craftsmanship.

guerby 1y ago

This kind of inverter usually have a setting to limit the current they can draw from the grid. From the manual of this particular model: https://cdn-files.myshopline.com/file/store/1675916196960/ANJ-3KW-24V-LV-WIFI.pdf https://cdn-files.myshopline.com/file/store/1675916196960/AN... 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.

Scoundreller 1y ago

> 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.

novaleaf 1y ago

> 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? PS: op took down their page. archive link is here: https://web.archive.org/web/20251005022124/https://sunboxlabs.com/ https://web.archive.org/web/20251005022124/https://sunboxlab...

a_mechanic 1y ago
Not the person you are replying to, but a GFCI does not protect against overcurrent.
- novaleaf 1y ago
  thanks, I'll put a breaker in-line.
- IAmBroom 1y ago
  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).
rsync 1y ago
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.
jagrsw 1y ago
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.

whatevaa 1y ago

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).

eternityforest 1y ago
Unless there's a fault with the fridge of some sort.
IAmBroom 1y ago
The duration is not the issue; gross energy size is the issue. The inrush is probably longer than a lightning strike...

t917910 1y ago

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.

deleted 1y ago

[deleted]