Posted by: @agentgeorge

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As we have had the topic issue resolved, we can edge off track a bit,

Erm... no we can't!

The issue first raised by the OP may be resolved in that the Growatt Ark batteries are alive once more.
However he's still awaiting a response from the DNO (UKPN) regarding the 60A Service Fuse.

The loading applied to this single-phase supply is beyond what would normally be 'acceptable'.

Depending on the distance to the local substation and the number of dwellings it serves, I would expect phase-imbalance to be of concern.
Losses due to phase imbalance are around 10% in GB, which is unsustainable.

As we've seen elsewhere on this Forum, the export levels being approved by UKPN are less stringent than the guidance issued by the ENA.

That's partly due to the topology of their LV grid, but if their losses are higher than elsewhere then it still needs addressing on a case-by-case basis.

The time to do that is now, because the Regional Energy Strategic Plan (RESP) bodies are developing the RIIO-ED3 Agreements which
will form the basis of the next Licences issued to DNOs by Ofgem.

There's a lot more going on in the background that will be apparent from a cursory reading on this discussion topic.

Let's pick up the discussion from this post,

and ignore the bits in-between... with the exception of the post from @agentgeorge  about AC/DC electric shocks,
which I said needs a new topic.

Posted by: @transparent

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Whatever UKPN say about the Service Fuse upgrade from 60A, please let us know.

If they insist on a move to 3-phase, please don't be daunted.
We can help to explain what's involved both during and after that upgrade.

It would mean you'd have your Smart Meter changed too.
That's fine.
I'm a Smart Meter specialist and I can answer whatever you'd like to know.

An upgrade to 3-phase under these circumstances shouldn't require you to pay anything.

You will, however, be asked to divide the household circuits across more than one phase.
We have photos of your consumer units here, and I already have an idea how to achieve what's required at minimal cost for the electrician's time.

Let's wait and see what UKPN say first.

As promised, I am posting back with an update.

I eventually managed to have a reply.

After some back and forth UKPN asked me to use their new online system which allowed checking if I needed a fuse upgrade.

It turns out I do. This is the output of the survey:

"Great! That’s the first step completed.

Based on the answers you’ve given, we’ve calculated that you need to upgrade your electricity supply to a three phase supply to meet your needs and help you become more environmentally friendly.

What’s involved?

This requires more work than a fuse upgrade and is chargeable. You’ll need a new cable to be installed and connected to your home or property from the street. We’ll need to know a few more details from you and may need to visit you before we can work out how much it will cost. Don’t worry, it may sound like a lot to do, but we’ll break it down into easy steps and guide you along the way. More information is available on our website."

I assume I have correctly answered their questions but even if I didn't, when they will come they will be able to rectify it.

I hope it won't be too expensive!! 🙁

Posted by: @transparent

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An upgrade to 3-phase under these circumstances shouldn't require you to pay anything.

From what I see, the work to upgrade the cable, etc all the way to your meter is safety related and UKPN is the only one handling this. 

Posted by: @transparent

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You will, however, be asked to divide the household circuits across more than one phase.
We have photos of your consumer units here, and I already have an idea how to achieve what's required at minimal cost for the electrician's time.

Let's wait and see what UKPN say first.

This would not be too expensive, some rewiring beyond the meter.. You should be able to get your own electrician for it. 

Looking forward to @transparent advice!  

Posted by: @eliuccio

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This requires more work than a fuse upgrade and is chargeable.

That's not always the case.
Let's see what they say once you responded to the extra details they're after.

Batpred is correct that the new supply cable and Service Fuse are likely to be "non-contestable works".
That means only UKPN may undertake the work.

It would have some "contestable work" if the cable route passed across the highway, for example.
There are 3rd party contractors who have licences to dig trenches on the public highway, and they can be cheaper than using the DNO.

If the cable passes through your own front garden, or beneath a drive or path on your own property, then you can obviously save money by digging that trench yourself.

The UKPN online advice page is unclear as to the requirements for you to have a new electricity meter box outside the property.

Point-1 indicates that is mandatory.

Point-4 suggests it's a recommendation.

It was certainly desirable to have an external meter position before Smart Meters became available in 2015, so it could be seen by a meter reader.
But I don't see why it's necessary if your existing Smart Meter position within the house is already proven to be working.

The point of having a 3-phase supply is that you divide the household loads across the phases.

However, it isn't possible to do this evenly because each circuit takes different current!

You already have two Consumer Units, and I believe the lower one only serves the heat pump.

The minimum that would expected of you is that two of the three phases are divided between those two CUs.
It isn't compulsory to use the third phase.

If your electrician suggests that the loading for the upper consumer unit is still too great,
then I'd recommend placing a third, 6-way consumer unit beneath the cupboard, and use this solely for the 32A connection to the EV charger.

That still leaves the top CU with the solar inverter and the storage battery connected to it.
Thus the household loads which will use the solar and battery will stay on the same phase as those devices.

I'm slightly puzzled by that top CU still having a trip marked as "Central Heating".
I don't know what that's connected to now that you're using a heat pump! 

@eliuccio 

I was wondering how this progressed? Please do not feel obliged to update us if it is still under evaluation! 

Dear @batpred,

thanks for asking! I thought I made this applications months ago but it was not listed in the system. Hence I clearly didn't 😭 

I just made one (100amp).

I hope I will be fine. The battery is now working fine, and I have optimised the whole system for Octopus Go.

But I will definitely benefit from this upgrade!

Hi All,

I had a UKPN surveyor visit my property last week and he said I do not need a 3phase in his opinion (this is a major work that for the amount of energy I may draw seems unjustifiable). He proposed though an upgrade of the fuse to 100 Amp which should cover all my needs and would require no expense on my part.

He said though that I need first Octopus to change the cables: "Currently, your private wiring is ok with 25mm Tails, however your Meter Tails will need to be changed as they are only 16mm currently. You’re supplier (whom you pay your bills too) will need to be contacted and they will make this change, once complete, UKPN can upgrade the fuse (subject to internal checks)."

He also said that I can of course consult with my electrician before we do the job but essentially he seemed to highlight that I was going to have to spend 9/10 grand for no reason...Not only that but the new electricity box to be placed outside would be quite incumbent and difficult to place anywhere in my specific case.

I now wonder how long Octopus will take to come over and do that cable replacement.

Thoughts?

Thanks,

E

Posted by: @eliuccio

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Hi All,

I had a UKPN surveyor visit my property last week and he said I do not need a 3phase in his opinion (this is a major work that for the amount of energy I may draw seems unjustifiable). He proposed though an upgrade of the fuse to 100 Amp which should cover all my needs and would require no expense on my part.

He said though that I need first Octopus to change the cables: "Currently, your private wiring is ok with 25mm Tails, however your Meter Tails will need to be changed as they are only 16mm currently. You’re supplier (whom you pay your bills too) will need to be contacted and they will make this change, once complete, UKPN can upgrade the fuse (subject to internal checks)."

He also said that I can of course consult with my electrician before we do the job but essentially he seemed to highlight that I was going to have to spend 9/10 grand for no reason...Not only that but the new electricity box to be placed outside would be quite incumbent and difficult to place anywhere in my specific case.

We had our supply upgraded a long time ago and I do not remember those tails needing replacement. Possibly it was done when we had the smart meter installed, a lot of people were reluctant so they made it as easy as they could. I do not remember this requiring any payment to our supplier (a small company that merged with what was a similarly sized octopus). Whoever came just swapped the cables under the stairs.. 

That's excellent news for you @eliuccio 

Yes, it's technically the Energy Supplier's responsibility to ensure that the meter tails are of the required size.
I'm surprised the Smart Meter installer used 16mm² wire when that job was done.
There's nothing wrong with him installing 25mm² tails just because your Service Fuse is only 60A.

I'm also very surprised at the cost estimate of £9k – £10k which would've been charged if you'd need a 3ph upgrade.
That suggests to me that the underground cable route is particularly complex, and crosses areas of ground owned by more than one 3rd-party.

I'm now going to be the only person in Britain to point out that the engineer from UKPN isn't correctly implementing the policies!

1: There's another reason why UKPN should be moving customers to 3ph supplies.
It reduces the losses due to phase-imbalance at the local substation transformer.

At present, however, this requirement isn't part of their RIIO-ED2 Agreement with Ofgem.
So DNOs can ignore it with impunity.

2: Other DNOs are embarking on a mission to down-size Service Fuses to 80A where a 100A is currently fitted.
Here's the explanation for that on National Grid's website.

100A fuses were ok when most domestic high-demand was of short duration, such as electric shower.

However, the advent of electric car-chargers has resulted in sustained high-current demand.
This can result in excess current being passed back to the substation transformer via the Neutral conductor.
That suffers thermal stress and might cause a power cut.

Downgrading fuses to 80A acts as a 'trigger' to ensure that houses with higher demand are told to upgrade to 3ph.

This issue has been discussed by DNOs within the ENA working groups, so UKPN should be well aware.

Overall, this is yet another example of UKPN working differently to the rest of the nation.

Bizarre!