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Gareth J
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You can't satisfy the house's requirements for 30ma and the inverter's requirements for 100ma in the same consumer unit. It's confusing that the manual shows this layout but maybe in other countries it would be acceptable.
I would show the installers the fact the manual states the inverter needs 100ma and ask them to fit that from a separate feed. They really ought to have done this anyway in my opinion.
I would show the installers the fact the manual states the inverter needs 100ma and ask them to fit that from a separate feed. They really ought to have done this anyway in my opinion.
Red'n'Black
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Just to be clear, that schematic wasn't out of the inverter manual, that was in some docs generated by the installer. It all looks very 'boilerplate' to me but it does match what I can see in the pics.
Yes my assumption was they would feed the inverter in upstream of the main CU. It's a long time since I looked at any wiring regs but surely this is covered in there somewhere?
J1nx
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That display will likely be for current/power measurement and is labelled as the heat pump, it will likely have a belden cable going back to the heat pump controller but it may not and may just give you a local display of energy consumed. You may also have another current clamp somewhere so the heat pump can monitor total load so as to not exceed the properties supply.
All that can be confirmed when they come back and put the solar inverter on a dedicated RCD/RCBO.
Is the night storage heater circuit now redundant? Could possibly use that or swap out the rotary isolator local to the CU and install the required kit there?
All that can be confirmed when they come back and put the solar inverter on a dedicated RCD/RCBO.
Is the night storage heater circuit now redundant? Could possibly use that or swap out the rotary isolator local to the CU and install the required kit there?
MetalMonkey
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That seems like it is a transformerless unit, so it is also worth checking everything is watertight as well.
Original RCDs will be 30mA
You don't want to swap the RCDs out, 100mA isn't suitable for protecting final circuits - if the unit requires one they will have to split the tails and put it on a seperate CU, which is the better solution to be honnest.
You will probably get some pushback on that though as it will mean pulling the main fuse - might be a good time to get an isolator put in as well, sometimes the DNO will fit them.
Gareth J
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This.
The installers need to follow both the manual and the regs. They should have fitted an inverter that was happy with a 30ma RCD if they wanted to do it the way they have.
J1nx
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Looks like an isolator in the second pic?
Red'n'Black
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According to the inverter manual, it has an internal 100 mA RCD, the note says any external RCDs in the circuit need to be rated the same or higher.
Would something like this work:
So keep the 'PV' breaker in the same CU, but move it so it connects directly to the main switch, upstream of the house RCDs? There is at least one redundant slot in the CU that was used for the storage heaters, so there is room to shuffle things around if needed. Would that be compliant with the regs?
The inverter is in the same cupboard as the CU and meter, so no worries about weather protection.
I'll be up there tomorrow, it looks like I'll be having a conversation with the installer on Monday. But to get rid of the nuisance trips in the short term, just turning off the rotary isolator between inverter and CU should work?
Gareth J
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Just turning off the inverter should do stop the tripping. If that's at fault.
Not qualified to comment on your wiring suggestion. I suspect that the wiring should have protection at both ends. After all, electric can come from either the grid or the inverter.
Not qualified to comment on your wiring suggestion. I suspect that the wiring should have protection at both ends. After all, electric can come from either the grid or the inverter.
sparkysy
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Just to add to @MetalMonkey s post above. That existing 30ma rcd is type AC and only likely rated at 63amps or maybe 80amps if your lucky, it also won't be bi-directional which is also a requirement for PV systems now.
It is most likely the source of the tripping.
I would definitely go over the other circuits on that RCD with an insulation tester just to make sure the other circuits are still healthy while I was there, and I would do some mA clamp testing too!
It is most likely the source of the tripping.
I would definitely go over the other circuits on that RCD with an insulation tester just to make sure the other circuits are still healthy while I was there, and I would do some mA clamp testing too!
Bobtail4x4
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we had the same problem years back when panels were installed, when it rained, half an hour later, the breaker would pop,
if I sprayed a hose on the panels the same,
turned out one cable fitting wasnt fully pushed in,
pay monkeys etc...
if I sprayed a hose on the panels the same,
turned out one cable fitting wasnt fully pushed in,
pay monkeys etc...
MetalMonkey
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I missed that picture, yes, and it looks like an economy 7 meter too - with the isolator then it should be fairly simple for them to alter things then.
@Red'n'Black IIRC Wylex did some dual tariff boards, might be worth whipping the cover off and having a look at how it is configured with the off peak supply.
Red'n'Black
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Well today's visit got cancelled, due to most of my route being under water
As far as I know the old Economy 7 meter is gone, replaced with a smart meter shortly after she moved in.
But yes I was going to pull the cover off anyway and megger all the existing circuits, just for elimination.
Mum is going to ring the installer tomorrow and tell them the symptoms, will be interesting to see how they respond. Funnily enough it hasn't tripped for the last few (very dull) days, I don't know if it would get worse with higher panel output?
I'll be back up there next weekend, will see what I find.
The inverter won't fire up and deliver power from the PV panels to the mains if there is no incoming supply present. The solar inverter logic is designed to check that the incoming supply voltage, impedance and frequency are within set limits, before delivering power to the electricity network.
brightspark
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i was working on a job other week it had one mainswitch and one rcd . the mainswitch controlled 4 nightstore heaters fed with tails to the off peak supply and the rcd was used as a mainswitch fed with tails from the domestic supply. i marked it up properly saying isolate both supplies so no one would just isolate the mainswitch thinking the whole lot was off
