5 ms·

British industry and standards bodies think this is an unsafe plan. Of course they would because it's work being taken away from them but it would be allowing

British industry and standards bodies think this is an unsafe plan. Of course they would because it's work being taken away from them but it would be allowing people to plug generators into ring finals with unidirectional breakers. It's not even guaranteed that the circuit is protected by anything newer than fuse wire or an MCB. No guaranteed earth leakage detection. No guaranteed surge protection. Relying on the cheapest inverters to sync frequency accurately. And I have more faith in German standards and work ethic than our own.

deleted 7mo ago
[deleted]
formerly_proven 7mo ago
The situation in germany is essentially the same, but that's why net supply by these is limited to 800 W. I don't think anything changes w.r.t. earth leakage, why would the presence of the solar supply change anything from the RCD and fault point of views, respectively?
- mytailorisrich 7mo ago
  Not expert but one difference is that in Germany the standard wiring is radial circuits with 16A MCBs while in the UK it's ring wiring with 32A MCBs. So in the UK we have 2.5mm^2 wires in a ring on a 32A MCBs... Of course a 2.5mm^2 wire is rated ~20A so any issues with the ring (sockets still work since connected from the other branch) can burn the wire before the MCB trips...
  - formerly_proven 7mo ago
    The "standard" wiring is 1.5mm² on 16A MCBs which are rated to trip at 1.13-1.45x nominal current (so 18-23 A). So this is already mildly improper because you can pull elevated currents continuously and dramatically shorten the life of the insulation.
    - kevin_thibedeau 7mo ago
      The rated ampacity of wire for electrical distribution has a significant margin on it.
  - PaulDavisThe1st 7mo ago
    Does anyone know the US equivalent terminology for a "ring final" ?
    - hamdingers 7mo ago
      We would call it "a serious code violation." It's prohibited in the NEC and always has been, it's objectively less safe. From what I understand the UK allowed it because of a severe postwar copper shortage and it persists to this day because it's allowed and a bit cheaper.
      - deleted 7mo ago
        [deleted]
      - bell-cot 7mo ago
        > From what I understand the UK allowed it because ... I'd say "severe post-WWII money shortage". After wartime expansion, the global copper industry could physically meet peacetime demands. But the UK was very close to national bankruptcy. And the Luftwaffe had turned an awful lot of their prewar housing into rubble. So - any cost that could be cut, was.
- oliwarner 7mo ago
  If your generator is plugged into their own circuit, it wouldn't change much. If you plug it into an overloaded ring final (which is not uncommon in the UK - half our house's sockets are on a single ring), you have to rely on the generator being able to detect faults to protect that circuit. You could also overload that circuit's wiring. If you have a a 16A Ecoflow, plug it into a 32A ring, you could draw 48A before tripping the grid circuit breaker, potentially causing significant heat in the wires. Dinky 3A generators won't do that but I don't think they're the limit our government are talking about.
fnordpiglet 7mo ago
I find it interesting because often the best way to achieve a safe building code is to learn by allowing with basic guard rails and iterating as things happen. This isn’t ideal for the rare individual impacted by the “things happening,” but collectively we refine and iterate. Our current standards weren’t arrived at by navel gazing - we got the codes we have by experience. It’s hard to realize that from the present that you can’t reasonably learn without doing and by constraining without learning prevents growth and learning.
- zdragnar 7mo ago
  Are there lessons on safety that need to be learned here? We already know what the happy path looks like, and we've plenty of lessons on what the unhappy path will look like. It isn't as if electric charge coming from balcony solar panels is some new magical-seeming type of electricity.
  - foxglacier 7mo ago
    Safety is statistical and depends on human behavior. Unexpected behaviors might appear. For example some places require a power outlet on kitchen islands because with out, people will use cords to the wall which creates tripping hazards. Also, why do wires have to be fixed to joists every 300 mm? It's not about the electrons.
- jerlam 7mo ago
  "Things happen" is a interesting way to say "houses burn down and kill everyone inside". And I don't believe that electrical standards were developed with the idea that houses could both consume and generate electricity. Not to mention that most houses aren't up to current electrical standards, much less fire codes.
labcomputer 7mo ago
“Unidirectional breakers” aren’t a thing for AC circuits.
- jonatron 7mo ago
  https://www.bgelectrical.uk/uk/circuit-protection/devices/rcbo https://www.bgelectrical.uk/uk/circuit-protection/devices/rc... Right there, both bidirectional and unidirectional breakers.
  - formerly_proven 7mo ago
    It would be really interesting to know what's so special about these UK units that they can be "damaged" by being fed from the "wrong" side (as per some other article), considering that the only place where these behave like that is an island north of France.
    - fy20 7mo ago
      These are not just circuit breakers/MCBs, they are RCBOs which combine an MCB + RCD in a single unit. RCDs traditionally only measure - and protect - current flow is one direction, so if you are using them for solar you need a bi-directional unit for full protection. The device will not be damaged, it just won't protect you. However in the case of a UK home, where you may have a single ring circuit connecting all the sockets on the whole floor, what's in the breaker panel isn't going to protect you with plug-in solar anyway. Better hope what you are plugging in meets UK standards and isn't just some Chinese rubbish that claims it does.
      - formerly_proven 7mo ago
        Outside the UK, neither RCDs nor RCBOs (type A/AC) are generally distinguished by bidirectionality (all search results about this being .co.uk), since the RCD part of these devices is just a current transformer driving a trip solenoid; there is nothing in it that's powered by the line, nor something which could sense net power flow direction. The situation is different for AFDDs or type B RCDs, since those have active, powered electronics in them which need to be fed from the line side. After some research the main reason seems to be two-fold: Answer #1: Many UK RCDs/RCBOs are actually single-pole devices and don't disconnect the neutral. In the simplest case, this means pressing the test button might burn out the test resistor when backfed. I don't imagine this to be a problem in practice, since grid-tie inverters shut down very quickly if the grid disappears under them, especially plug-in inverters. RCDs/RCBOs elsewhere are virtually always disconnecting the neutral, so don't care about this. Answer #2: It looks like some/many one-module wide UK RCBOs _do have_ electronics in them, even if type A, because they're actively driving the trip solenoid of the MCB part, and if you sketch this out and do it in a very cheap way it's easy to see how you could burn that out if backfed (i.e. powering the trip solenoid during a fault is assumed to disconnect in a very short amount of time, but if backfed for longer than the disconnect time that might be enough to toast the solenoid or the driver). Notably neither of these has anything to do with the direction of power flow.
password4321 7mo ago
I am not very well versed on this topic but I believe the balcony solar products market one of their safety features as "anti-islanding protection". Personally I wonder what happens if multiple balcony solar systems are connected... can each still tell when the grid is down since the other power source is active? https://www.digikey.com/en/articles/anti-islanding-and-smart-grid-protection https://www.digikey.com/en/articles/anti-islanding-and-smart...
- PunchyHamster 7mo ago
  people put few kW worth of micro-inverters and it is fine so I imagine that is figured out problem... question is whether the ones allowed for sale implement it well and are tested for it
  - PaulDavisThe1st 7mo ago
    my understanding is that micro-inverters send an "up and running" signal encoded over the DC wiring to the main inverter, and that this is used to detect micro-inverter failure. that is an entirely different problem than the one in the GP comment, i think.
    - theoreticalmal 7mo ago
      “Rapid shutdown devices” do this. Microinverters have the same “grid is down, turn off” logic as a main inverter
      - PaulDavisThe1st 7mo ago
        Again, entirely different to the point being raised. You have 4 neighbors, all with grid-tied inverters, all of which will do rapid shutdown if the grid goes down. The grid does go down ... but are there circumstances under which the presence of neighboring inverters will "hide" the grid being down from each inverter, and so they will keep delivering power back to the grid ?
- 7mo ago
eimrine 7mo ago
What is the reason about earth leakage? Shouldn't the generator be grounded for the sake of powering those devices which require a proper earthing? What do you mean by "guaranteed surge protection"? Are you an electrician to write like that?

deleted 7mo ago

[deleted]

formerly_proven 7mo ago

The situation in germany is essentially the same, but that's why net supply by these is limited to 800 W. I don't think anything changes w.r.t. earth leakage, why would the presence of the solar supply change anything from the RCD and fault point of views, respectively?

mytailorisrich 7mo ago
Not expert but one difference is that in Germany the standard wiring is radial circuits with 16A MCBs while in the UK it's ring wiring with 32A MCBs. So in the UK we have 2.5mm^2 wires in a ring on a 32A MCBs... Of course a 2.5mm^2 wire is rated ~20A so any issues with the ring (sockets still work since connected from the other branch) can burn the wire before the MCB trips...
- formerly_proven 7mo ago
  The "standard" wiring is 1.5mm² on 16A MCBs which are rated to trip at 1.13-1.45x nominal current (so 18-23 A). So this is already mildly improper because you can pull elevated currents continuously and dramatically shorten the life of the insulation.
  - kevin_thibedeau 7mo ago
    The rated ampacity of wire for electrical distribution has a significant margin on it.
- PaulDavisThe1st 7mo ago
  Does anyone know the US equivalent terminology for a "ring final" ?
  - hamdingers 7mo ago
    We would call it "a serious code violation." It's prohibited in the NEC and always has been, it's objectively less safe. From what I understand the UK allowed it because of a severe postwar copper shortage and it persists to this day because it's allowed and a bit cheaper.
    - deleted 7mo ago
      [deleted]
    - bell-cot 7mo ago
      > From what I understand the UK allowed it because ... I'd say "severe post-WWII money shortage". After wartime expansion, the global copper industry could physically meet peacetime demands. But the UK was very close to national bankruptcy. And the Luftwaffe had turned an awful lot of their prewar housing into rubble. So - any cost that could be cut, was.
oliwarner 7mo ago
If your generator is plugged into their own circuit, it wouldn't change much. If you plug it into an overloaded ring final (which is not uncommon in the UK - half our house's sockets are on a single ring), you have to rely on the generator being able to detect faults to protect that circuit. You could also overload that circuit's wiring. If you have a a 16A Ecoflow, plug it into a 32A ring, you could draw 48A before tripping the grid circuit breaker, potentially causing significant heat in the wires. Dinky 3A generators won't do that but I don't think they're the limit our government are talking about.

fnordpiglet 7mo ago

I find it interesting because often the best way to achieve a safe building code is to learn by allowing with basic guard rails and iterating as things happen. This isn’t ideal for the rare individual impacted by the “things happening,” but collectively we refine and iterate. Our current standards weren’t arrived at by navel gazing - we got the codes we have by experience. It’s hard to realize that from the present that you can’t reasonably learn without doing and by constraining without learning prevents growth and learning.

zdragnar 7mo ago
Are there lessons on safety that need to be learned here? We already know what the happy path looks like, and we've plenty of lessons on what the unhappy path will look like. It isn't as if electric charge coming from balcony solar panels is some new magical-seeming type of electricity.
- foxglacier 7mo ago
  Safety is statistical and depends on human behavior. Unexpected behaviors might appear. For example some places require a power outlet on kitchen islands because with out, people will use cords to the wall which creates tripping hazards. Also, why do wires have to be fixed to joists every 300 mm? It's not about the electrons.
jerlam 7mo ago
"Things happen" is a interesting way to say "houses burn down and kill everyone inside". And I don't believe that electrical standards were developed with the idea that houses could both consume and generate electricity. Not to mention that most houses aren't up to current electrical standards, much less fire codes.

labcomputer 7mo ago

“Unidirectional breakers” aren’t a thing for AC circuits.

jonatron 7mo ago
https://www.bgelectrical.uk/uk/circuit-protection/devices/rcbo https://www.bgelectrical.uk/uk/circuit-protection/devices/rc... Right there, both bidirectional and unidirectional breakers.
- formerly_proven 7mo ago
  It would be really interesting to know what's so special about these UK units that they can be "damaged" by being fed from the "wrong" side (as per some other article), considering that the only place where these behave like that is an island north of France.
  - fy20 7mo ago
    These are not just circuit breakers/MCBs, they are RCBOs which combine an MCB + RCD in a single unit. RCDs traditionally only measure - and protect - current flow is one direction, so if you are using them for solar you need a bi-directional unit for full protection. The device will not be damaged, it just won't protect you. However in the case of a UK home, where you may have a single ring circuit connecting all the sockets on the whole floor, what's in the breaker panel isn't going to protect you with plug-in solar anyway. Better hope what you are plugging in meets UK standards and isn't just some Chinese rubbish that claims it does.
    - formerly_proven 7mo ago
      Outside the UK, neither RCDs nor RCBOs (type A/AC) are generally distinguished by bidirectionality (all search results about this being .co.uk), since the RCD part of these devices is just a current transformer driving a trip solenoid; there is nothing in it that's powered by the line, nor something which could sense net power flow direction. The situation is different for AFDDs or type B RCDs, since those have active, powered electronics in them which need to be fed from the line side. After some research the main reason seems to be two-fold: Answer #1: Many UK RCDs/RCBOs are actually single-pole devices and don't disconnect the neutral. In the simplest case, this means pressing the test button might burn out the test resistor when backfed. I don't imagine this to be a problem in practice, since grid-tie inverters shut down very quickly if the grid disappears under them, especially plug-in inverters. RCDs/RCBOs elsewhere are virtually always disconnecting the neutral, so don't care about this. Answer #2: It looks like some/many one-module wide UK RCBOs _do have_ electronics in them, even if type A, because they're actively driving the trip solenoid of the MCB part, and if you sketch this out and do it in a very cheap way it's easy to see how you could burn that out if backfed (i.e. powering the trip solenoid during a fault is assumed to disconnect in a very short amount of time, but if backfed for longer than the disconnect time that might be enough to toast the solenoid or the driver). Notably neither of these has anything to do with the direction of power flow.

password4321 7mo ago

I am not very well versed on this topic but I believe the balcony solar products market one of their safety features as "anti-islanding protection". Personally I wonder what happens if multiple balcony solar systems are connected... can each still tell when the grid is down since the other power source is active? https://www.digikey.com/en/articles/anti-islanding-and-smart-grid-protection https://www.digikey.com/en/articles/anti-islanding-and-smart...

PunchyHamster 7mo ago
people put few kW worth of micro-inverters and it is fine so I imagine that is figured out problem... question is whether the ones allowed for sale implement it well and are tested for it
- PaulDavisThe1st 7mo ago
  my understanding is that micro-inverters send an "up and running" signal encoded over the DC wiring to the main inverter, and that this is used to detect micro-inverter failure. that is an entirely different problem than the one in the GP comment, i think.
  - theoreticalmal 7mo ago
    “Rapid shutdown devices” do this. Microinverters have the same “grid is down, turn off” logic as a main inverter
    - PaulDavisThe1st 7mo ago
      Again, entirely different to the point being raised. You have 4 neighbors, all with grid-tied inverters, all of which will do rapid shutdown if the grid goes down. The grid does go down ... but are there circumstances under which the presence of neighboring inverters will "hide" the grid being down from each inverter, and so they will keep delivering power back to the grid ?
7mo ago

eimrine 7mo ago

What is the reason about earth leakage? Shouldn't the generator be grounded for the sake of powering those devices which require a proper earthing? What do you mean by "guaranteed surge protection"? Are you an electrician to write like that?