Move Meter From Consumer Unit Because Of Problem Tripping

[steptoe]

what type RCD is that?

A or B ? I'd think its a bog standard RCD, quite a lot of inverters are NOT compatible with these.

and, the biggie, cos I really cant be AR said looking it up at this time of night,

is that inverter actually compatible with a 'normal' 30mA RCD

Ok Andy, there's nothing in the standards for fitting solar that says you can't share an RCD with the solar installation, but as we have discussed here on this forum it isn't a good idea. In the original guidlines from the NICEIC they even suggested tapping into and upstairs ring main - that changed pretty quickly.

Trouble with inverters is that on start up and shut down they can 'chatter' the AC connection relay, which RCDs do not lke, especially when shared with other circuits. I prefer to install a solar circuit on a non-RCD protected circuit, but as pointed out, the requirements for an RCD depends on the AC cable run, ie is it buried less than 50mm into a wall etc etc as is compliant with the current edition of BS7671. On TT systems I have fitted an RCD, not shared with any other circuit, and it has been fine. The fact that your system is starting to play up after several years suggests that something else is starting to fail - probably an appliance. Fronius is a top quality inveter, one of my favourites, and not some cheapo Chinese crap.

Your proposal to rearrange the solar onto a garage mini CU is absolutely fine and a cost effective option ( as long as your meter blocks are your side of the normal electric meter). It would be better on a 20A MCB and run in 4mm if possible - reduces cable losses for a few quid of cable. 2.5mm is fine, but I like to max system performance.  The inverter, I am assuming an IG TL 3.6, is designed to be 16A limited, now it will only output max 16A for a few hours, but I've always felt the circuit would be better on a 20A rather than running at the max value of the MCB at 16A

Hi binky,

you prob know off top of your head,

can they run off a standard 30mA RCD ?

 

[binky]

shouldn't be a problem Steps, I've never had a problem with inverters on thier own RCD anyway, but then I normally run cables in a way that doesn't need an RCD. I got into this habit after having tripping issues soem years ago when we tapped into a sub-board, I then decided that keeping inverters off an RCD was the best way forward.

 

[thebuckets]

what type RCD is that?

A or B ? I'd think its a bog standard RCD, quite a lot of inverters are NOT compatible with these.

and, the biggie, cos I really cant be AR said looking it up at this time of night,

is that inverter actually compatible with a 'normal' 30mA RCD

Hi binky,

you prob know off top of your head,

can they run off a standard 30mA RCD ?

shouldn't be a problem Steps, I've never had a problem with inverters on thier own RCD anyway, but then I normally run cables in a way that doesn't need an RCD. I got into this habit after having tripping issues soem years ago when we tapped into a sub-board, I then decided that keeping inverters off an RCD was the best way forward.

Ok Andy, there's nothing in the standards for fitting solar that says you can't share an RCD with the solar installation, so you can't just start calling them cowboys and bodgers, but as we have discussed here on this forum it isn't a good idea. In the original guidlines from the NICEIC they even suggested tapping into and upstairs ring main - that changed pretty quickly. If they were cowboys they would have fitted ac heapo Chinese inverter.

Trouble with inverters is that on start up and shut down they can 'chatter' the AC connection relay, which RCDs do not lke, especially when shared with other circuits. I prefer to install a solar circuit on a non-RCD protected circuit, but as pointed out, the requirements for an RCD depends on the AC cable run, ie is it buried less than 50mm into a wall etc etc as is compliant with the current edition of BS7671. On TT systems I have fitted an RCD, not shared with any other circuit, and it has been fine. The fact that your system is starting to play up after several years suggests that something else is starting to fail - probably an appliance. Fronius is a top quality inveter, one of my favourites, and not some cheapo Chinese crap. made in Austria to brick outhouse standards!

Your proposal to rearrange the solar onto a garage mini CU is absolutely fine and a cost effective option ( as long as your meter blocks are your side of the normal electric meter). It would be better on a 20A MCB and run in 4mm if possible - reduces cable losses for a few quid of cable. 2.5mm is fine, but I like to max system performance.  The inverter, I am assuming an IG TL 3.6, is designed to be 16A limited, now it will only output max 16A for a few hours, but I've always felt the circuit would be better on a 20A rather than running at the max value of the MCB at 16A

Cheers Binky and Steptoe,

the AC cable from the inverter was ran in 4mm and is routed through a boxed in section that used to house an internal soil stack (removed) which runs from loft to the ground floor under-floor space then comes up in the meter cupboard. there is an isolator at either end. would this be suitable for a non RCD installation?

All in all the installation looked ok to me apart from a few small things that I picked up on ( is there a spark out there who wouldn't be picky whilst having someone else work in their home?) and the fact that I wasnt happy with the meter and MCB wasting two ways on my board.

This problem has been going on for a while and I've always thought it was other things (is it the fridge kicking in? faulty extension lead etc etc) I don't have a PA tester or RCD tester so not been able to test apart from isolating and waiting to see if that solved it.

 

[thebuckets]

 Re: fronius ig 3.6 tl issue


hi dansk just to follow up on your susgeestions seen as you made the time to reply. All connections fine, phoned fronius and they replied immediately that it was the brand of rcd at fault and said i should replace with 100ma as volex too sensitive heh presto no issue



just found that at electriciansforums

 

[Lurch]

Re: fronius ig 3.6 tl issue

hi dansk just to follow up on your susgeestions seen as you made the time to reply. All connections fine, phoned fronius and they replied immediately that it was the brand of rcd at fault and said i should replace with 100ma as volex too sensitive heh presto no issue

just found that at electriciansforums

That's complete tosh. If the circuit needs 30mA protection then you cannot go around lowering protection willy nilly. The advice from Fronius should come with a load of provisos as it is not just a case of simply swapping the RCD. The chances are in a domestic installation the circuit will need a 30mA RCD or nothing so fitting 100mA RCD's is most likely pointless.

 

[binky]

make should have nothing to do with it, though Volex is in my opinion rubbish. Volex boards are a little famous for catching fire - I would change, if you have one, for a decent make like Hager. If you have swopped out the shared RCD for a 100mA unit, then you have to ask have you removed 30mA RCD protection from circuits that need it. Your first suggestion of a separate mini CU is probably far better. Should you decide to change the board, then buy a 'high integrity unit' so you have 1 or 2 ways which aren't RCD protected, or even better fit the board with an RCBO per circuit - see forum sponsor SBS Dave for a very reasonably priced unit.

Now if your installer has run the AC in 4mm, then that is good and points towards a better installer. The fact that it is run down a boxed in stack pipe means it isn't buried in a wall, and in my opinion doesn't merit RCd protection. The current regs requirements are aimed at cables buried in plaster work or in stud walling, that can't move when 'hanging a picture' or the like. There's little chance you would want to bang a 4inch nail into boxing to hang a picture, even if you did the cable is loose and free to move away from said nail should you decide to do that one day.

Can I assume the inverter is in the attic? If so how hot does your attic get in summer? If pretty damn warm I would suggest installing some extra roof vents, this will help keep the inverter cool, more efficient, and prolong its overall life span. I would also suggest, if your installer didn't supply a small dispaly to put on a windowsill where you can easily see it, buying one of these , but necessarily from Amazon.

http://www.amazon.co.uk/geo-Solo-II-PV-microgeneration/dp/B00BIGEOSE

They come with an internet link, which I don't bother with, but with this display which reads the LED pulses from your generation meter, you will be able to see exactly what your system is doing. This in turn will help you maximise your energy savings, and also tell you if the system has failed for some reason.

 

[thebuckets]

Cheers Binky,

That was a quote from electriciansforum that I found that seemed to point to the fact that others are having problems with RCDs and their Fronius inverters.

My Board is Wylex which I'd always found decent along with the MK gear which I used when I rewired.

yes the inverter is in the attic and it does get hot in summer so vents sound a good idea. 

think that a dedicated board for the PV might be the way to go but I'll check the prices on the sponsor site first

thanks for your help, much appreciated

 

[binky]

No probs and please ignore the grumpy buggers on here :^O

RCD tripping is not unique to Fronius, they all do it. Listen to your inverter starting up, and you will see why.