Nowty Towers Vs UK Grid Storage

[Tinbum]

Re the fuse i dont know how they decide. I had a new 3 phase supply installed and had requested a 50kva transformer for both my supplies. The DNO put in a 100kva and 100A fuses on both supplies. It only feeds us. When the suppliers fitted the meters one supply fitted 100A with 25mm meter tails and the other swaped the fuses and fitted 60A fuses with 16mm tails. When my smart meter was fitted a few months ago the installer said if my tails had been 16mm they would have changed them and the fuses to 100A. It seems to be up to who you are with not the DNO as to what you get.

[Oldgreybeard]

I had (naively) assumed that having a 100 A fuse meant we had a 23 kVA supply, but they sent me a copy of the regulations they work to (standard apparently, for all DNOs) that made it clear that they were only required to supply a maximum continuous power of 13.8 kVA (60 A at 230 V) to any domestic installation. They did warn that we must not exceed 60 A continuously, and that if we did I would need to request a three phase supply, with it's maximum total rating of 41.4 kVA (assuming they would allow 3 x 100 A, which is really 3 x 60A).

I would question this. You have to pay extra at install for 100A. A friend was building a new property on plot of three and they only had 60A each because it would have cost more to have 100A. If you are in fact being limited to 60A then may be you should have some money back.

I did question it at the time. The explanation I had from the DNO seems reasonable. They stated that the fuse is only to protect the cable, and as our meter and associated cables were all 25mm then a 100A fuse was OK to protect them. The supply continuous rating is a lot lower than the fuse rating, and determined by a set of rules all the DNOs have to follow. These rules state that they need to provide a continuous power per installation of up to 13.8kVA, so that is the maximum continuous power any home can normally draw. If we needed to draw more than this continuously, perhaps if we had two car chargers, then we would need to upgrade the supply to three phase.

The cost we paid for the connection was for a 15 kVA supply, fused at 100 A, according to the contract paperwork from the time. I believe that the 13.8 kVA figure is something to do with a newer set of rules, as that is what they fell back on when this discussion was going on. At the time, 15 kVA was the maximum single phase supply option on their connection form, there was no option to have a higher single phase supply. There was no cost difference between the different supply options, as they needed to run a new three phase cable across a small pond to us, and we are only using one of the three phases. There are only a small number of houses (about six) connected to the transformer here, so there is plenty of spare capacity and we are the only house on the end of this cable. I was tempted to pay the extra £300 to have three phase, but at the time I didn't think we would ever need it, but I wasn't thinking ahead far enough to getting an EV.

[ALAN/ALAN D]

Hello Ladies / Gents

I was trying to start a new Topic. But get.

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[Joeboy]

I had (naively) assumed that having a 100 A fuse meant we had a 23 kVA supply, but they sent me a copy of the regulations they work to (standard apparently, for all DNOs) that made it clear that they were only required to supply a maximum continuous power of 13.8 kVA (60 A at 230 V) to any domestic installation. They did warn that we must not exceed 60 A continuously, and that if we did I would need to request a three phase supply, with it's maximum total rating of 41.4 kVA (assuming they would allow 3 x 100 A, which is really 3 x 60A).

I would question this. You have to pay extra at install for 100A. A friend was building a new property on plot of three and they only had 60A each because it would have cost more to have 100A. If you are in fact being limited to 60A then may be you should have some money back.

I did question it at the time. The explanation I had from the DNO seems reasonable. They stated that the fuse is only to protect the cable, and as our meter and associated cables were all 25mm then a 100A fuse was OK to protect them. The supply continuous rating is a lot lower than the fuse rating, and determined by a set of rules all the DNOs have to follow. These rules state that they need to provide a continuous power per installation of up to 13.8kVA, so that is the maximum continuous power any home can normally draw. If we needed to draw more than this continuously, perhaps if we had two car chargers, then we would need to upgrade the supply to three phase.

The cost we paid for the connection was for a 15 kVA supply, fused at 100 A, according to the contract paperwork from the time. I believe that the 13.8 kVA figure is something to do with a newer set of rules, as that is what they fell back on when this discussion was going on. At the time, 15 kVA was the maximum single phase supply option on their connection form, there was no option to have a higher single phase supply. There was no cost difference between the different supply options, as they needed to run a new three phase cable across a small pond to us, and we are only using one of the three phases. There are only a small number of houses (about six) connected to the transformer here, so there is plenty of spare capacity and we are the only house on the end of this cable. I was tempted to pay the extra £300 to have three phase, but at the time I didn't think we would ever need it, but I wasn't thinking ahead far enough to getting an EV.

Interesting to read of the 13.8kVA limit. Doesn't leave THAT much excess for home battery charging and storage heaters after a7kWh EV load is on. Stick a dishwasher and washing machine timed as well, heat the HWT and we'd soon be bumping on that limit for short periods of time through the night.

[Stinsy]

I’ve heard that some DNOs are now fitting 3-phase to new-build domestic dwellings as standard.

I don’t think that washing machines/dishwashers are the problem. While their 3kW heating elements pull a fair few amps, they do so only fleetingly. It is the EV charging points and heat-pumps that are the problem, they draw full power for hour after hour. The real problems occur if they’re doing this during the evening peak.

[Ken]

If the 100A fuse is protecting the input cable then what is the point of restricting the supply to 13.8kw as against 23kw.

In the new leccy world this is going to be unworkable and unless a good reason it needs to be replaced with something fit for the modern world.

If i add up all my loads including diversity i would be above 100A but in practice not a chance but the 13.8 kw is something else again

[Joeboy]

Hello Ladies / Gents

I was trying to start a new Topic. But get.

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The Topic was going to be about
"
Is there any electricity providers that do not charge a £?? amount per day charge.
What are the best deals. "

You need 10 post's I think before having full functionality.

[Oldgreybeard]

If the 100A fuse is protecting the input cable then what is the point of restricting the supply to 13.8kw as against 23kw.

In the new leccy world this is going to be unworkable and unless a good reason it needs to be replaced with something fit for the modern world.

If i add up all my loads including diversity i would be above 100A but in practice not a chance but the 13.8 kw is something else again

I've just dug out the paperwork and email exchanges I had with the DNO at the time I had the new electricity supply run to the land where our house now sits. This dates back to 2013, so may have been superseded. The form I filled in to request a supply from SSEPD had lots of tick boxes.

Looking at the form I ticked detached, electric heating, electric cooking, heat pump and electric water heating. The only boxes I didn't tick were direct electric heating, storage heating and one about the number of motors and welders.

The reply I got back from SSEPD was an Excel spreadsheet form, with our new connection reference number, that I had to fill in and return to them with loads of stuff on it requesting details of all of the loads, including lots of questions about the heat pump current, power factor correction, motor starter method, starting current, running current, etc, as well as lots of questions about all the other electrical appliances and their ratings, so induction hob, two ovens, water heater, whether I was going to install microgeneration, and if so the rating, etc, etc. This form also asked whether I wanted single phase or three phase.

A few weeks later they sent me very brief form that looked to be a standard one sent to all new connection applicants, with several supply options. This just says that they were proposing to provide a "standard 15 kVA domestic supply". I emailed then to ask if that was the maximum available and also to ask about microgeneration and if they would be OK with it being more than 3.6kW. The reply I got was a bit convoluted, and came from an engineer at the local depot, not the people I'd been dealing with. His email says that there was plenty of spare capacity on our transformer and he was proposing to run a new 95mm three phase overhead cable to a new pole in the corner of our land and that this would easily support their maximum domestic service of 15kVA.

There's a scribbled note from a telephone conversation with this chap, confirming that we'd have this 95mm three phase cable right to our meter cabinet, so could have three phase if we needed it. There's also an informal comment that he couldn't see any reason why we couldn't have up to 10kW of microgeneration on a single phase supply, or 30kW if we wanted a three phase supply.

The next bit of paper I received was an estimate for running in the new supply, with different price options for each bit of itemised work. This quote also says that the proposed supply is a "standard 15kVA domestic supply", and says that a 100A fuse will be fitted in the meter cabinet, with this cabinet to be supplied and installed by me, to the specification that attached to the quote, before they did the work.

The next correspondence with them was a few years later when I installed the car charger. I completed the mandatory notification form online and this is when things went downhill. They phoned and told me to isolate the charger and not use it until they had approved a total demand assessment. They followed this with a letter saying the same. It was during the process of getting them to agree that I could use the charger that the new 13.8kVA figure was raised, and they never did answer my question as to why I wasn't allowed the 15kVA that I'd contracted for, they just said their rules had changed. After a few weeks of faffing around with me doing a few days of load measurement, with a hired logger, they removed the prohibition on using the charger.

[Ken]

i suspect that the 15/13.8 kw saga is due to the changing of the voltage used which would have been the nominal 240V but when we changed to nominal 230V (EU) they probably used the lower tolerance fig so that no one can complain like i did back along when the V was below spec.

Does not answer the question why restrict to 13.8kw

This is a eg of the modern business world where the quango types throw out rules with the prime objective of "no blame" culture and the business man is forced to "bend" the rules or not be in business. I suspect by the rule of 13.8 kw then very few houses have a legally fitted EV charger and are certainly not going to have in the future. I suspect that the 15kw/13.8kw rule goes back to that which legally we are all entitled to and no way is the DNO going to go further -why should they-just open themselves up to legal claims when there is an electrical fire. So now we have electrical fitters probably operating illegally in order to adapt to what is required in the modern world. PS could be wrong but..

[Stinsy]

I’ve watched a lot of YouTube videos where electricians install Zappi EV charging points. They usually fit a CT to avoid overloading the supply, particularly in houses with and induction hob and electric shower. However they always set the Zappi to 100A or whatever the main fuse is rated at.

I’ve never seen an installation where they set the Zappi to moderate total power draw to 60A when a 100A main fuse is present. Often the EV charging point installation involves an upgrade of the main fuse from 60 or 80 to 100A.