BOD is on the money yet again. When I got my 3-phase supply, the DNO wanted to know why. They were interested in the use of motors, but accepted that 3-phase ones were less likely to make the lights flicker on start-up.


I am not sure that it is fair to blame the DNO when large (very large) loads are subsequently installed.

Its a non post, the poster just wants the DNO to do the calculations, we get it all the time. This is clearly an additional load, and we require a declaration. Perhaps he can come on here and tell us the calculations he has arrived at. I doubt we will hear of those though.


Regards, UKPN

Believe what you want UKPN, the response I’ve seen from the DNO is pathetic (I’ve only just taken up the case), and I have done the measurements, calculations and submitted a detailed report, and await the outcome. Have worked for the CEGB -power stations- that was a while ago!), and most recently, as a Council Electrical Contracts Engineer (a hobby during retirement), and even surveyed total plant and services for major NHS hospitals (some of them are in a mess!), and much more. Including as a drives engineer and controls specialist over a long career in the industry. I am very use to having to do such investigations, but not up to date with latest Reg’s (several years into retirement), hence the question on here, and appreciated the answers. Now sitting on it awaiting DNO response. Back in 2006, after initial early retirement, I also completed the C&G2391, not because I needed it, but because it looked interesting, and found in practice that some of it could be nearly as difficult as earlier degree and HNC’s exams, and back then, most failed it, but I think they have simplified it since.

PFlyWheel:

Thank you all for you input, it’s helped a lot. I’ve also had the DNO confirm 100 amp’s approved, although how they can expect voltage to stay in limits with a supply cable impedance near the TNS 0.8 ohm limit, I don’t know. 

So the DNO have confirmed a 100-amp supply.


If you attach the loop tester to line and neutral I would expect a lower reading than around 0.8 ohms, however I am now picturing a nice house in a rural or suburban location with a long run of DNO cable supplying it that was installed many years ago when the maximum demand of installations would have been expected to be a lot lower, indeed this is probably the first time the system has been stressed.


Andy Betteridge 

I’ve also had the DNO confirm 100 amp’s approved


Poetic interpretation I expect of the answer to "what size is my cut-out fuse" rather than what is my Authorised Supply Capacity (ASC) which is typically 12, 14 or 15 kVA.


Most consumers don't like the quote of £8k? to upgrade their ASC or to allow "disturbing loads" to be connected.


Regards


BOD

As it is TNS I am assuming the DNO cable is at least fifty years old and the house has probably been extended considerable since it was installed.


Andy Betteridge.

Yes, confirmed 100 amp in writing following their voltage technicians data logging exercise, and in some earlier correspondence too.. The situation, which started with a request for a 3-phase supply very much earlier this year, when pool heat pumps were being considered, has dragged on for a very long time and I'm now looking for a quick resolution. I only got involved, casually, a few weeks ago. My report has apparent been sent to the DNO today.

So we've gone from considering to actually having them installed without getting the supply upgraded then. As before, it appears the cost of getting the supply upgraded was deemed unnecessary so the install went ahead and now the reasons for a paid for increase in ASC have come home to roost.......

 The situation, which started with a request for a 3-phase supply very much earlier this year, when pool heat pumps were being considered,

For the installation I’m looking at (for a friend, so just out of interest in my retirement), the current demand, by domestic standards is large, and includes heat-pumps for both house and pool, and these in particular are being adversely affected by the low voltage. There are implications too re the COP of heat pumps and lots more with at these low voltages, so I have just submitted a comprehensive technical report to the DNO and asked for an urgent response.


Regards


BOD

Please keep us updated as and when.


I've posted here re a friends supply where the DNO wanted a percentage of a transformer upgrade and cable costs to supply 3-phase, yet the offered single phase supply capacity to the existing house was going to be downgraded. For those who remember the post, it is still ongoing. Strangely the transformer was replaced (at no cost to my friend) but even with binoculars unable to determine its rating. (It supplies 4 houses and an agricultural building - which is where my friend wanted the 3-phase supply. (I even went to where SP store their new transformers and took photos through the fence where I could see rating plates for comparison purposes!)


Clive