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koos147 avatar image
koos147 asked

(DO NOT) Combine neutral on multiplus

Hey all,


i found a lot of posts about boats/campers. however i am not sure about a house.

I want a multiplus to solve a bad grid connection.

Our earth connection is a large ground pin. not connected to the neutral. so i guess there is no problem in combining this on all connections.

however i am not sure about the neutral.

from the switchboard to the place where i want to mount the Multiplus is a 4 wire cable (non replaceable)

so all i want to do is use the L1 as grid to the AC in. and use the spare wire as AC out.

Both the neutral and ground should be shared by AC in and AC out.

Stole the bellow picture from another post to make it a litle bit more clear)

1710507395963.png


Extra point is, the cable is 2.5mm2 so i should limit the usage to 32A but i think that is something the software of the multiplus can solve (I will also provide a fuse on the hot sides of both wires)

Multiplus-IIgrid
1710507395963.png (20.7 KiB)
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Michelle Konzack avatar image Michelle Konzack commented ·
You mean 25A or 20A?


If you send 32A over a 2,5mm2 MultiCore Cable you will cook it.

For 32A you need at least 4mm2.



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koos147 avatar image koos147 Michelle Konzack commented ·
i checked that a massive core cable 2.5mm2 can handle 32A of power.

would be more ideal to replace the cable. but i need to destroy the whole garden for this.

25A is currently the max we have. so would be no problem to limit it to 25A the power assist to 32A was was just a bonus.

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Michelle Konzack avatar image Michelle Konzack koos147 commented ·

Realy:

strombelastbarkeit.jpg


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strombelastbarkeit.jpg (133.9 KiB)
koos147 avatar image koos147 Michelle Konzack commented ·

Strange, when asking the same question in dutch, the answer is 32A. but digging its a single site. there are a lot of 2.5mm cables who claim they are rated for 32A. but didn't like to gamble with electrics.

Above result is for UK. (as far as i know the only country using ring circuits?)

so the problem i left with is, can massive cables buried in the ground handle 25amps. or do we need to skip the whole plan and keep claiming defect devices on the Insurance.

as told in the opening post. destroying the whole garden isn't an option. so its the cables currently available or nothing.

Also, apart from the outcome, i am still curious about the initial question.

/edit
just for te fun, never trust googles summary
1710512523960.png

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3 Answers
duivert avatar image
duivert answered ·

Hi i’m a certified electrian from the netherlands

With my own 3ph ess multiplus setup


2.5mm2 solid wire can go up to 25A, but if the distance is more then 25m it should be 4mm2


Also this is not allowed!

Because combining the neutral from ac in and ac out will add the current up!

So in your case the max you can do with this cable is 12,5A on ac in and 12,5A on ac out

Its dangerous in case of an grid failure! The multiplus can not disconnect grid this way!

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koos147 avatar image koos147 commented ·
thanks,


i was expecting a that the input and output would cancel each other out.

but end conclusion is that ESS isn't an option without destroying the garden or building another location for it.

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mjs500 avatar image
mjs500 answered ·

Earth connection is a large ground pin. not connected to the neutral. so TT earth arrangement in UK not dno suppled with RCD before the switchboard or CU

and supplied from transformer ?

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koos147 avatar image koos147 commented ·

I know the solution in the uk is a little bit different.
here it is common to have 1 or more devices functioning like a RCD (
earth leakage circuit breaker (c) Google translate)

so i have 2 RCD's both serving 5 16A fuses. no circuits without the rcd

Our outlets don't have anything included (as a matter of fact, we can put our plugs 2 way, swapping neutral and line without knowing it ;) )


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daza avatar image
daza answered ·

@koos147 i wouldn't do that combining the neutral's as one it won't allow isolation of the grid, if anything is connected upstream ie before the multiplus2 there is no safe isolation, should grid go down either power cut or regular maintenance you could be giving someone a bad day possibly kill them as even if the AC input relay in the device triggers it will still feed back to the grid as its been in effect bypassed.

I know OP not cheap neither is a house if insurance don't payout and come on we all know they like to take the money when it comes to paying out any excuse will do please don't make it easy for them.

I would suggest best option to upgrade the cable size and make sure its armoured 5 core cable. Biggest size you can get in your budget as allows expansion of for a bigger multiplus if you ever want more capacity

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Related Resources

MultiPlus-II Product page 

MultiPlus-II Manual

MultiPlus-II 230V Datasheet 

VE.Bus Error codes

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