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Minimum Voltage at incoming supply point
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
Question
Retired now and not up to date with reg’s since 16th. Helping advise a friend. Currently they have 100amp single phase supply and whilst the no load voltage is up at around 238 volts, as the circuit is loaded, voltage drops off substantially. Even with a load of 50 amps, ie, half the supply fuse rating, voltage is slightly below the -6% limit, at around 215 volts, further load simply pushes voltage significantly lower, and by extrapolating measured data, it would be nearer 170 volts with a load of 100 amps, is this acceptable? I plan measuring Ze and pfc this week as a guide perhaps to supply loop impedance and, which I suspect must be causing this excessive drop. I’m aware of the ESQCR reg’s although need to update myself, but are there any other regulations that apply?
 
111 Replies
Chris Pearson 11001208764
Joined 05/12/2018 - 1367 Posts
I have reviewed my paperwork at home.

The contract with the DNO to install a supply was for a maximum capacity of 100 Amps subject to an after diversity maximum demand of 30 kVA.

I cannot find any reference to maximum supply in the contract with my supplier, including their deemed contract.

It seems unlikely to me that a developer would pass on such details to a first occupier, and even more unlikely that the details would survive a succession of occupiers. So, in the vast majority of cases, only the DNO would know what was contracted originally. Whether they can disclose that information is entirely dependent upon their record keeping.

Incidentally, I assume that most electricians would put the fuse rating (or 100 A if unknown) in the box for "maximum demand" in an EIC because the ADMD will probably not be known, especially for alterations and additions.
AncientMariner 69763
Joined 14/12/2004 - 254 Posts
Reply from SP this morning:-
Quote/...
Good Morning Clive,
Thank you for your recent email.
We only hold records for half hourly supplys.
In order to asess what is in the property we would recommend applying for an additional load so that we can carry out a network study and advise you on the current capacity.
If you require any further assistance please do not hesitate to contact us.
Kind regards
SP Energy Networks Contact Team
Lister Drive
Liverpool
L13 7HJ
0845 270 0783
.../unquote.

Actually, looking at the ESQCR http://www.legislation.gov.uk/uksi/2002/2665/contents/made 
Information to be provided on request:-

28. A distributor shall provide, in respect of any existing or proposed consumer’s installation
which is connected or is to be connected to his network, to any person who can show a reasonable
cause for requiring the information, a written statement of—
(a) the maximum prospective short circuit current at the supply terminals;
(b) for low voltage connections, the maximum earth loop impedance of the earth fault path
outside the installation;
(c) the type and rating of the distributor’s protective device or devices nearest to the supply
terminals;
(d) the type of earthing system applicable to the connection; and
(e) the information specified in regulation 27(1),
which apply, or will apply, to that installation.
 

27.—(1) Before commencing a supply to a consumer’s installation, or when the existing supply characteristics have been modified, the supplier shall ascertain from the distributor and then declare to the consumer—

(a)the number of phases;

(b)the frequency; and

(c)the voltage,

So it would seem that the ASC is not something that the DNO should know?  That sort of implies that you can have what the cut-out fuse will allow? Perhaps as in using the words that some mobile phone operators use  to sell data say, "All you can eat" !

Strange though their reference to half hourly metering, we have half hourly metering in our village hall, but I thought that was a supplier thing, rather than the DNO?

Clive
 

FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
Great response Clive, and I’m following with interest.
 
AncientMariner 69763
Joined 14/12/2004 - 254 Posts
Our contract is with Gulf Gas & Power UK.

I responded to SP's email late Monday night, including:-
Quote/...
Grateful if you can please advise, how an Electrician "can advise what I have at the moment"?
The Cut-Out fuse carrier may be marked 100A, but that does not mean that it contains a 100A fuse and my understanding is that the ASC and the actual Cut-Out fuse rating may not go hand in hand. In any case the Cut-Out is sealed.  
I have been advised that this information is, or should be, held by the DNO.
For info, our property was built circa 1959, no mains gas, heating by open coal fires.  Later, pre 1970 three storage heaters were installed on an Off-Peak tariff.
.../unquote.

The storage heaters were removed 2002 as was the Off Peak meter and time switch and the cut out and meter moved into a built in meter box (via split-con on the cut end of the PILC supply cable, TN-S earthing. Gas fired CH was installed during building works.

Anyway, nothing has come back so far (pm 12th) from SP.

Clive
 
Chris Pearson 11001208764
Joined 05/12/2018 - 1367 Posts

AncientMariner:
I'll give Scottish Power one thing, they are quick; but....

From: GettingConnected@ScottishPower.com [mailto:GettingConnected@ScottishPower.com]
Sent: 11 November 2019 15:11
To: clive@xxxxxxx.uk


Good Afternoon Mr Carver
Thank you for your enquiry.
Please be advised that we do not hold capacity information.
We as the distributor would be responsible for upgrading the supply if this is required.
An electrician would be able to advise what you have at the moment and if you require an upgrade.
Please feel free to contact us if you would like to discuss this any further.
Regards
SP Energy Networks Contact Team
320 St Vincent Street
Glasgow
G2 5AD

I need to ask an Electrician, who do you suggest?    😉

The lack of DNO records seems remarkable. However, your contract is with the supplier (who, of course, may be one and the same) but in any event, one or the other of them ought to know.

So you decide to sue your supplier over their failure to maintain the voltage. Their defence is that the ASC has been exceeded. I don't think that the Judge will be impressed if they can produce no evidence as to what was agreed.
Kelly Marie 11001211805
Joined 18/07/2019 - 274 Posts

UKPN:
Our esteemed "adviser" won't feel the cold Kelly, there will be so much hot air around him.!!!😂🤣😃
Regards, UKPN

Lol had to laugh at that no offence meant to the OP
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
As I too am finding out, such questions can lead to a long drawn out iterative process, but perhaps they simply mean “get an electrician to check the size of their sealed fuse”!
 
AncientMariner 69763
Joined 14/12/2004 - 254 Posts
I'll give Scottish Power one thing, they are quick; but....

From: GettingConnected@ScottishPower.com [mailto:GettingConnected@ScottishPower.com]
Sent: 11 November 2019 15:11
To: clive@xxxxxxx.uk


Good Afternoon Mr Carver
Thank you for your enquiry.
Please be advised that we do not hold capacity information.
We as the distributor would be responsible for upgrading the supply if this is required.
An electrician would be able to advise what you have at the moment and if you require an upgrade.
Please feel free to contact us if you would like to discuss this any further.
Regards
SP Energy Networks Contact Team
320 St Vincent Street
Glasgow
G2 5AD

I need to ask an Electrician, who do you suggest?    😉

Clive



 
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
Thanks BOD, and you are right, I should stick to direct inbox discussion for off topic social chats, and will do this. As for further declaration of data re this particular friends installation, please see my latest response to MKNP. Thanks again for your input.
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
I consider that your posts have been somewhat abusive from the outset MKNP, and I responded accordingly. Thankfully, I have had a tremendous amount of help from others who have posted and am hopefully now back up to speed again near 10 years into retirement. As for the data asked for, it's probably not strictly relevant to the question I asked for advice on, and until I've had an opportunity to talk directly to the DNO (in response to my report to them), it's best that I don't talk numbers on a site like this as never know how many spies about, and how they may twist my answers, nor how they may want to use the data. As far as this load is concerned, I've had some amazing replies from a specialist heat pump forum, and it’s reminded me of what was day to day knowledge for me back then of drives and refrigeration systems and its basic theory generally. Particularly helpful today too has been a response on my associated post here on the IET forum page that one of the members who has also responded here, has given me, great stuff.
Once I've had direct discussion with the DNO and agreed a way forward, I'll happily share the outcome with members of this site that are genuinely interested.

 
UKPN 1100233915
Joined 17/12/2014 - 87 Posts
When I politely asked for the MPR, I was severely reprimanded, He said he did not have to justify his data/calculations to me. What he misses is the massive help and support he would get if he disclosed such detail. But who are we?
Regards, UKPN. 
perspicacious 20955492
Joined 18/04/2006 - 321 Posts
With this being the 100 post total, apart from the social updates, we've yet to actually be told what kVA was applied for and its associated cost.............Why is this?

and an upgrade price of £8k would be a bargain.

Regards

BOD
Alan Capon 20740443
Joined 27/12/2005 - 347 Posts

FlyWheel:
But of course, getting the supply limit data out of them before such a situation is detected, may be like trying to get blood out of a stone, so I suggest assuming their supply fuse represents that "ultimate" limit is not unresonable.

They should know the ASC for every property, whether specifically applied for, or a default. The information is needed for the calculations for a new connection, to determine what (if any) network reinforcement is required as part of the quote. It is likely that the ASC will be less than the supply fuse. Some DNOs in the UK fitted a 100A fuse regardless, others tried to fit a fuse closer to the ASC. 

Whether the DNO were aware of all the additional load tagged on is questionable, however it will be obvious from the voltage / current traces they have, together with a rough size of the motor loads, and their start / stop regimes. The cost of the supply upgrade will depend on what is needed to deliver three phase to the property. It may be easy, or it may be difficult (read “expensive”). 

Regards,

Alan. 
Sparkingchip 72796851
Joined 18/01/2003 - 2255 Posts
I think the simple truth is that in many cases the DNO don’t know the data, because the network is not being used as it was designed.

Earlier this year I did a job in South Wales and posted some pictures of the suppliers tails at the intake, it is the only overhead five wire TNS earthed system I have seen, I definitely have not seen such an arrangement in this neck of the woods.

Sat having a coffee one evening I followed the cables both ways on Google Street View, I was genuinely surprised how many homes are being supplied by this run of cables with probably at least a third of the homes having been built and added to the supply during the time the cables have been in place.

The must be many places where the network is already stressed and simply cannot cope with EV charging and heating loads unless the extra demand is applied overnight.

Andy Betteridge 
ebee 81966746
Joined 02/12/2004 - 665 Posts
It might be easier to get blood out of a stone then try to pass the whole assembley thru the eye of a needle
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
But of course, getting the supply limit data out of them before such a situation is detected, may be like trying to get blood out of a stone, so I suggest assuming their supply fuse represents that "ultimate" limit is not unresonable.
Sparkingchip 72796851
Joined 18/01/2003 - 2255 Posts
One of my former customers is on the Sunday Times Rich list, he only has a four bedroom house, but it is the bed four bedroom house you will probably ever see.
The house has two three phase supplies rated at 60-amps, one in the house and the other one in the swimming pool house with the pool being electrically heated with traditional heaters.

Another customer has ground source heat pumps and a solar photovoltaic array installed a few years ago which he makes a profit on when it’s running, so leaves the heating on whilst on holiday, though that may not be possible with a new set up.

As I passed comment above the answer to the problem is probably to throw some money at it as an investment that will reap future benefits, however it does need the DNO, metering services and suppliers to cooperate and getting them to do so can be a long process.

Andy Betteridge 



 
broadgage 70728247
Joined 07/08/2007 - 315 Posts
Perhaps the agreed supply capacity is "whatever the network can supply without the voltage dropping below 217 volts" Or put another way, "if the voltage drops below the statutory limit, this must be the customers fault for overloading the supply"
UKPN 1100233915
Joined 17/12/2014 - 87 Posts
"Is that still the career path?
Thank you for asking. For the traditional craft apprenticeship route, UKPN is currently training 93 apprentices in how to repair, maintain and connect overhead power lines.(lines people), underground cables (jointers) or electricity substations (fitters)

Regards, UKPN
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
Nice one, I look forward to seeing their reply! 
FlyWheel 11001213225
Joined 04/11/2019 - 40 Posts
Good times Alan, Did you ever visit Walter's International Club there in those days (Valley road, near town centre), I've had some great evenings there, and meeting up with a guy that sang there in those days on Wed evening. He sang with the then Wild Oats, but these days, just enjoying his retirement entertaining us in the Vulcan once a month, where the landlord Trevor is also an amazing guitar player.
 
AncientMariner 69763
Joined 14/12/2004 - 254 Posts

Chris Pearson:

broadgage:
Before complaining though, do try and ascertain what the agreed supply capacity is.

Have we had an answer to this important question please?

 

Not always easy to find out the ASC is.  Being curious of ours at home, I contacted our DNO, Scottish Power, and gave them our full address and postcode together with the Supply number. This December last year..I received a reply back a couple of days later,

Quote/...
Good Morning Mr Carver
Thank you for your email with regards to the above address.
Unfortunately SP Energy Networks do not deal with this type of enquiry.  However, your supplier Gulf Gas and Power should be able to assist you in this matter so please contact them on 08008303670 to discuss this further.
.../unquote.
I did as I was told and telephoned Gulf Gas and Power, who as expected, told me they they didn't know and to ask my DNO!

The reason that I was curious was that I witnessed the meter change at the identical property next door. I asked the Engineer what rating the cut-out fuse was (ours from similar witnessing is 80 amp) and he opened up the fuse carrier to show a 60 amp fuse bypassed with a paperclip! The cut out was previously sealed, but in fairness to the previous sealer, the paperclip was not visible and only became so when the fuse was removed to sight the rating. Needles to say the 60 amp fuse was o/c.  

Since that was nearly a year ago, I have just emailed Scottish Power's Liverpool address again to ask the same question. This is the address which their website says to contact for Connections, Alterations and Disconnections. I will share their reply in due course.

Clive
Alan Capon 20740443
Joined 27/12/2005 - 347 Posts

FlyWheel:
No, even closer Alan, the Vulcan Arms. . . 

Ok, that would be Leiston  then. In the days of the CEGB, I was involved with communications to the Sizewell site. My site contacts were in the Instrument Maintenance Department of Sizewell “A”. I got to know some of the favoured pubs around the station! 

Regards,

Alan. 
Sparkingchip 72796851
Joined 18/01/2003 - 2255 Posts

UKPN:
We have a guy rod, 71, has spent 56 years in the job (overhead linesman). Started as an apprentice in 1963 aged just 15.
Regards, UKPN

And when he does retire will he be replaced by a graduate?
Sparkingchip 72796851
Joined 18/01/2003 - 2255 Posts
Ah, well! Often the solution to a problem is to throw money at it.

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