WWilts

Electric supply single vs three phase

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3 minutes ago, Wagas said:

 

I have the same view on future proofing but not sure it's worth paying £8k. I've already paid £5k to UK Power to get power to the plot. Estimated house value will be £750k so it's not a huge %. Still not sure 

For 8k you could get some walk on glazing and have change .....

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16 minutes ago, pocster said:

For 8k you could get some walk on glazing and have change .....

 

£7,999.50 in change to be exact

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6 minutes ago, Moonshine said:

 

£7,999.50 in change to be exact

Made me cry 😿 

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1 hour ago, andy said:

I even have a smart meter but that was a battle and a half to get...


😭😭😭 go on, rub it in 😭😭😭

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We didn’t ask for a single phase connection but the 3 phase connection here was £1261. A while ago now though. 
 

 

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1 hour ago, newhome said:


😭😭😭 go on, rub it in 😭😭😭

It’s not a SMETS2 one if that helps 😬

 

I’m still trying to get SSEN to take away my unrequired single phase overhead supply but we’ll get there…

 

Don’t forget, all these connection and disconnection activities are zero VAT rated for new builds (inc. disconnection on demolish and rebuild) and they have no problem refunding you retrospectively.  Andy’s top tip of the day!

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3 minutes ago, andy said:

It’s not a SMETS2 one if that helps


Don’t you need a SMETS2 to take advantage of the time of use tariffs? Who put it in for you? 
 

 

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3 hours ago, saveasteading said:

For years I asked sparkies what was the principle of 3 phase, and they didn't know. 

This is what I think I now know.

 

3 phase is necessary for heavy industry. The 3 power supplies are out of phase with each other (peaks and troughs are 1/3 apart) (like pistons in a car, don't all push at once) ) so that the power is smoother as well as more powerful at 440V.

Machinery also lasts longer, because of the 'smoothness'.

But you can take power off each supply at 230V.

 

I have no idea if fast car battery charging needs 3 phase, but iIdoubt it.

 

So unless you need to operate heavy machinery, then it doesn't need to be 3 phase, and you can have a bigger, single phase supply instead.

 

All gurus:    If any of that is wrong, then please do tell.

OK, I'm tired so this might be a bit of a bad explanation, but it all comes down to how electricity is generated. When you move a magnet past a wire, it induces a current in the wire. In practice going in a straight line isn't practical, so you end up with a rotating magnet. This is also why electricity is delivered as a sine wave.

 

Now it's worth noting that electricity is delivered as a current. For a domestic single-phase system, that means it arrives on the Live wire and returns to the grid down the Neutral wire - with both wires carrying the same amount of current: the number of electrons entering and leaving need to match.

For a power station and transmission system that's a pain in the backside - only half your wires actually transmit useful power, and with a single phase your generator has got lots of empty space inside which could be used for something different. This is where three-phase is really helpful - as you can see from the .GIF below, the sum of all the three currents in a three-phase system is always zero. That means for instance that you can create a neutral within the generator by tying the three windings together, and the neutral wire on the supergrid pylons is the little thin one at the very top of the pylons, with all the other wires carrying power.

 

Best Solid Ein GIFs | Gfycat

This feeds back to why big electrical loads need to be attached to a 3-phase supply: if the loads aren't balanced then either you get a distorted sine wave or more likely you start sending a load of current down the neutral wire.

 

Turning 3-phase into domestic single phase is easy: you send out the three phases plus the neutral wire from the transformer, and each house gets one live phase and a neutral, which brings the voltage down from "415V" (the phase to phase voltage) to "230V" (the phase to neutral voltage).

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Just realised I missed something important: you can achieve the same thing with two phases (say the two A phases above - wire one forwards and one backwards). However, for a big motor that isn't very helpful because it can't easily create a rotating magnetic field. With a 3-phase system, you can wire the motor stator up in the same way as the generator shown above, and it'll create a rotating magnetic field which follows the same path as the magnet in the .GIF above.

Virtually all big motors do this, albeit in most case they use a squirrel cage induction rotor which lets the motor run slightly slower than the grid frequency.

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12 hours ago, newhome said:


Don’t you need a SMETS2 to take advantage of the time of use tariffs? Who put it in for you? 
 

 

I believe as long as it says secure on it, it's OK.  I have this one:

https://www.camax.co.uk/product/secure-sprint-211

 

And I'm using Octopus and they say as long as a SMETS1 meter has "Secure" on it, it is OK.  It's submitting readings every 30 mins to them.

https://octopus.energy/agile/new/

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7 hours ago, andy said:

And I'm using Octopus and they say as long as a SMETS1 meter has "Secure" on it, it is OK. 


I want to switch to Octopus too. I’ve been on their list for over a year and they’ve told me that it will be a very long wait 🙁

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57 minutes ago, newhome said:


I want to switch to Octopus too. I’ve been on their list for over a year and they’ve told me that it will be a very long wait 🙁

I’m on octopussy . Took a while to sort the meter to smets2 and then for the Borg collective to take over MY Tesla battery 

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3 minutes ago, pocster said:

I’m on octopussy . Took a while to sort the meter to smets2 and then for the Borg collective to take over MY Tesla battery 

 

Changed to Octopus about 5 or 6 weeks ago. It took a month from asking for them to come and fit a SMETS2 meter (they did it this afternoon).

 

Apparently it takes up to 2 weeks for everything to connect and sort itself out, and after that you can go on whatever whacky tariff you want.

 

The installer was excellent. He did an extremely neat job - the result is a lot tidier than the original network installation. 

 

He also mentioned they're an amazing company to work for.

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4 minutes ago, jack said:

He also mentioned they're an amazing company to work for.

My installer mentioned how (expletive deleted)ing amazing I am - which is of course true .

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1 hour ago, pocster said:

My installer mentioned how (expletive deleted)ing amazing I am - which is of course true .

Don't know why you (expletive deleted) wit (expletive deleted) are laughing - that's exactly what he said - HONEST!

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13 hours ago, pocster said:

Don't know why you (expletive deleted) wit (expletive deleted) are laughing - that's exactly what he said - HONEST!

I never cease to find you a source of amazement. And several other things too.

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Back to three phase vs single phase.

 

I'm no electrician but work with lots of computers in datacenters with 3phase power and we use geothermal and solar in some countries.

 

something to consider with solar power and 3 phase costs.

Upto 3.6Kw solar on single phase does not need permission from DNO.  Above 3.6kw needs permission,  I have permission for 10kw on single phase.

3 Phase solar Invertors distributes the power generated across each phase evenly.  To use this power rather than export it your workloads need to be balanced, easy with 3 phase devices like car chargers,  impossible for most domestic workloads.

 

secondly maximum demand billing,  you are billed 3 x usage of the highest demand phase.  if you have unbalanced load you are paying at the peak usage of the highest phase for all 3 phases. Imagine this scenario,  everything in your house is single phase, oven lights ect,  your 3 phase is used by a car charger, & heat pump. When you are not charging your car, your phases are out of balance as only the single phase consumer unit is consuming electricity, but you are being billed at 3 x the rate. Unless you have a 3 phase consumer unit and your loads are balanced you are paying more.  and of course maximum demand billing is very well known with commercial customers,  lots of new domestic customers will have bill shocks and of course the power companies are not explaining this when promoting 3 phase.

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32 minutes ago, Scoobyrex said:

To use this power rather than export it your workloads need to be balanced, easy with 3 phase devices like car chargers,  impossible for most domestic workloads.

Not true if you have net aka vector sum metering.  Bascially you are only billed for what you consume not per phase in isolation, so if you use 2kW on phase 1 and export 1kW each on phases 2 and 3, you don't pay for anything.

 

34 minutes ago, Scoobyrex said:

if you have unbalanced load you are paying at the peak usage of the highest phase for all 3 phases

Not true either I'm afraid in a domestic sceanrio.

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You must be in a very fortunate location with 3 Phase smets2 meters that support vector sum.

 

Not available for my install, and maximum demand billing applies.

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15 minutes ago, Scoobyrex said:

You must be in a very fortunate location with 3 Phase smets2 meters that support vector sum.

 

Not available for my install, and maximum demand billing applies.

Note you don't have to be on SMETS2 meter to get vector sum / net metering. e.g. Sprint 211 supports it.

(But conversely, having a SMETS2 is a good way to ensure it, as it's part of the SMETS2 spec)

 

Most meters support multiple modes, and on a domestic supply it should be possible (pandemic aside) to find a supplier that will put you onto net metering. When I spoke to my supplier about this a couple years ago, they admitted they often get this wrong at first install and need to send a technician back multiple times to get it right.

YMMV

 

 

 

 

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42 minutes ago, Scoobyrex said:

You must be in a very fortunate location with 3 Phase smets2 meters that support vector sum

SMETS1 Secure 3 phase meter here, not SMETS2.

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What electricity outfits did you sign up with to get a meter that supports vector sum.  My current supplier has been less than helpful and I could still potentially switch from single to 3 phase and change as UKPN havent started the work yet.  I can manage on single phase, but well 3 phase is more power scotty.

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1 hour ago, Scoobyrex said:

What electricity outfits did you sign up with to get a meter that supports vector sum.  My current supplier has been less than helpful and I could still potentially switch from single to 3 phase and change as UKPN havent started the work yet.  I can manage on single phase, but well 3 phase is more power scotty.

In that case you might as well get UKPN to put in the 3 phase head whatever, if it doesn't cost much more. All my research (talking to UKPn in particular) was that you can definitely get any supplier to put a single phase meter in on it, but having the 3ph head now will give you future flexibility should you ever need it. 

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