Plug in balcony solar UK , just a Lidl question

[JohnW2]

https://electrical.theiet.org/wirin...-march-2024/bidirectional-protective-devices/

“The concern highlighted by BEAMA is that a voltage present on the outgoing terminals of the protective device, either due to the device operating in the event of an earth fault or by use of the functional test button, could cause irreparable damage.”
That’s where i read about 2 issues with unidirectional rcds ,whether true or not

I'm not at all sure how an RCD could suffer as the result of it operating because of an earth fault. For a start, that would merely mean that (if it were a unidirectional RCD) the electronics would remain powered after the trip (which is the situation which the devices normally happily live with for years or decades)and, in any event, the device tripping (hence disconnecting inverter from grid) would presumably very rapidly result in the inverter shutting down, wouldn't it. ... but, as always, maybe I am'missing something'!

The second issue, relating to use of the test button with a unidirectional RCD during export, is the one we have been discussing at length in this and other recent threads - and would seem to be an unavoidable potential risk, albeit far from quantified.

 

[mikehammer69]

I didn’t understand it myself

What that second issue if any could be

 

[JohnW2]

I didn’t understand it myself ... What that second issue if any could be

That makes two of us, then ... but it would be a little worrying (and would make us rather sceptical about anything which came from BEAMA) if the 'experts' at BEAMA were imagining an issue which doesn't actually exist - so, in some senses, I might hope that you and I are both 'missing something'!

 

[ericmark]

Thank you, @mikehammer69 the report states

The product standard for RCBOs states that if it is necessary to distinguish between the supply and load terminals, they shall be clearly marked, for example.

So with RCBOs, we can, it seems, identify between the two types.

The 'typical' residual current circuit-breaker (RCCB) is an electromechanical device, however, electronic RCCBs also exist. RCCBs for consumer units are in the form of a two module-sized device. These devices are not usually marked in and out, and therefore are bidirectional.

So it seems this also covers the RCD, so all we need is like when we get a meter change, and they mark the fuse size on the DNO fuse, we can have the RCD/RCBO type marked on the CU. So from date of this instruction, it will take 5 years for all rental accommodation in England to be marked up.

quite apart from the fact that it would be a bit rich if a buyer did not see this until after he/she had bought to product

This is clearly a problem. We don't tend to read instructions before purchase, however we have the same problem with ovens above or below 3 kW and a large label saying how many kW seems to be enough.

 

[JohnW2]

"The product standard for RCBOs states that if it is necessary to distinguish between the supply and load terminals, they shall be clearly marked, for example."

So with RCBOs, we can, it seems, identify between the two types.

I'm not so sure about that. Most, if not all, RCBOs have a 'flying lead' for the supply-side N (with the load-side terminals marked as such) - so it is clearly possible to determine the intended orientation of installation - but I don't really see how that can be taken to indicate whether or not a device is 'bidirectional' (I suspect that a high proportion of those ion service are not).

You quoted:

"The 'typical' residual current circuit-breaker (RCCB) is an electromechanical device, however, electronic RCCBs also exist. ...."

That statement is surely way behind the times, hence a serious understatement, isn't it? Whilst the earliest RCCBs were, indeed, purely 'electromechanical', I thought that for a very long time virtually all of them used 'electronics'. Is that not the case?
Your quote goes on to say ...

".... RCCBs for consumer units are in the form of a two module-sized device. These devices are not usually marked in and out, and therefore are bidirectional."

I also have serious doubts about that statement. The vast majority of RCCBs in-service in CUs are, indeed, 2-module-sized devices which rarely, if ever,have 'in'and 'out' markings - but it has always been my understanding (reinforced by the diagram usually on them) that they were unidirectional devices. Is that not the case?

So it seems this also covers the RCD, so all we need is like when we get a meter change, and they mark the fuse size on the DNO fuse, we can have the RCD/RCBO type marked on the CU. So from date of this instruction, it will take 5 years for all rental accommodation in England to be marked up.

Hmmm. I'm not at all sure about that, either. If, per what you quoted, the requirement is that (if it is necessary to distinguish between the supply and load terminals), then they should be clearly marked to that effect, I suspect they meant 'clearly marked by the manufacturer', not by an EICR inspector. Apart from anything else, in the absence of any 'manufacturer markings', how is the EICR inspector going to ascertain for certain whether the device needs such a label/marking? Furthermore (as emboldened text above), what you quoted only requires such 'clear labelling/marking' IF the device is unidirectional - so absence of such labelling could either mean that it's bidirectional or else that no-one has yet considered applying a label!!

I think that all of this (IF it were proposed) would need a lot of 'thinking through'!