Follow up question: quote for connection and local supply issue

Hi Morgan


The increase to 185mm cable would undoubtedly cope with your load, but that may be oversimplifying the problem. It is not just the cost of the cable, but the cost of the trenches which they wish to share. You need to see the overall estimated price of the works, and the proportion which you are expected to pay to find out, and they may not wish to give you this figure! As suggested the lowest cost to you would probably be the 60m cable from Sub just to your property, but they wish to do much more than this. The largest cost of any of these schemes is likely to be the "civils" as we call them, the digging and construction works, not the electrical ones. You could try to get a quote from a groundwork contractor to trench the sub to your property and backfill after the cable is laid, which would probably be quite reasonable, and put this to WPD as a scheme. They would then want the connecting costs etc. to be added, but this would not be huge. The trench across bare land would probably cost less than £2k, (2 days total for digger inc backfill) and the cable etc perhaps the same again (50mm wavecon). That should give you a potential 200A 3 ph supply. Warning: they will make a lot of noise! Changing the whole run to 300mm is not a fair way to get the upgrade which I expect is urgent for them.

Wow, this gets worse.  going from 95mm2 to 185mm2 increases capacity by at least 100A/phase  (ratings from low-voltage-aluminium-waveform-cable (elandcables.com)).  Unless you need more than 69kVA (I doubt you will get anywhere near that) then 185mm2 should be fine unless the existing cable is seriously overloaded.


If the existing cable is that overloaded you could argue that they should be overlaying with 185mm2 anyway.   A lot will depend on the extent of the overload and how much power you need.  Further enquiries and a bit more precision on your own needs could save you some more.


If you do end up at 300mm2 I would push to ensure that its only the cable cost and not the civils that you are paying a contribution too.  Also you only need to pay up to your service joint for the difference.  the rest of the run to the pole over the road should be down to WPD. Push them for a detailed breakdown.


I cant read the updated plan its too blurred when I blow it up

Thanks statter‍ and davezawadi (David Stone)‍ .


What they are proposing is the same as the original plan - to dig from the Tx at Drakewalls Mine, across the neighbour's field/garden and down the driveway, under the road and to the pole across the road. However, instead of me paying for this digging, they are proposing to pay for this. This is what the chap from WPD said:

To get the price down I had to speak to my manager and came up with different way of looking at the quote. As our network is right on the limit, he agreed for me to look into how we could make this work.
 
By replacing the existing cable with the next size up our network will be ok. But it still does not work with your new supply, so the cost you are asking about is the difference between next size up cable and a cable that will allow your connection. As we would have to replace the cable that is in the ground sometime, my manager has agreed for WPD to take on the excavation works for the mains cable overlay.


Instead, they want me to pay the difference between the cost of the 185mm2 cable that they say they would have put in (if they were doing a simply upgrade), and the 300mm2 cable they say they need in order to be able to provide me with a supply. The current supply is in the form of a 95mm2 cable, from Drakewalls mine over to the pole, and then up and down the street on two 55mm2 ABCs. 


I asked WPD two questions:

1. Are you sure that you cannot provide my home with a supply (1ph 15 KVA) by overlaying the 95mm2 cable with a 185mm2 cable, and,

2. If you are going to future proof your work, why are you not considering installing a 300mm2 cable anyway, given that last week the PM announced phasing out petrol and diesel cars by 2030.


The answer to the first question was 'no we cannot'. I didn't get any additional explanation, and I am not wholly convinced that this is true. 


The answer to the second question was "As far as the announcement from the government, there is no blanket upgrade in place, it is case by case upgrade as when needed". This seems to me a non-answer really. I didn't ask if there was a blanket upgrade, only that if they were going to be doing an upgrade anyway, why not future-proof it in light of what they know about the direction of travel. If a 185mm2 cable won't provide me with a supply, is it really going to be suitable in 10 years' time when everyone has an EV charging point and a heat pump...


So what I'm trying to establish is, what is the veracity of the claim that they could not provide me with a supply by installing a 185mm2 cable. And are they asking me to pay for an upgrade cable that they really ought to be putting in anyway.


Here is a (hopefully clearer) copy of the plan of work.

proposed plan of work WPD.pdf


Many thanks

M

The quotes I've arranged from WPD have previously given a detailed breakdown of costing split between non-contestable connection works and contestable connection works Morgan.

Examples from a selection being:


Assessment and design £786.00

Wayleaves £745.00

Lay 185 mm2 cable in trench 230 m £2823.48

LV 185 mm2  cable 250 m £4536.63

Pole termination £471.09

Travel £139.85

Erect average pole £702.58

HV switching 8 hrs £126.52

Travel £41.07

Fused cut-out single-phase £55.92

Travel £69.71

All plus VAT


Regards


BOD

I am not sure what "overlay" means. Does it mean that a 185 mm² cable will be added to the existing 95mm² one or replace it?


If it is replacement, then the added current carrying capacity is around 100 A per phase, which is a wee bit more than you want, but it does seem to gobble up most of the extra. So if they were upgrading, they would use 185 mm², but with the addition, it has to be 300 mm²; in which case it would not be unreasonable for you to pay the difference at least to your service cable.


On the other hand, if the new cable is added, there would appear to be plenty of capacity to supply the new build with 185 mm² cable so I can see the problem from Morgan's point of view.


Equally, one might argue that if the cables are paralleled, an extra 95 mm² would have done, but now 185 mm² is required instead. So either way, it doesn't seem unreasonable to me to be asked to contribute to the cost of next size up.


Somebody more learned than I will doubtless explain.

By replying Chris I'm not claiming to be more learned, but my understanding is that the term "overlay" is exactly that, they leave the existing in place and put another cable adjacent/over it.

Normally as a complete replacement from the use of Aluminium sheathed cable (the term eludes me!) which has had severe corrosion issues from where the sheath has been damaged and allowed water ingress (any 4x4 owner of certain brand will know all too well the warts/scabs that form on the body panels!) and is replaced with wavecon cable with the copper strands (but Al cores).

Not necessarily of a greater ccc (sorry Morgan, current carrying capacity) but replaced to maintain a healthy network with less risk of loss of neutral.


Regards


BOD

Many thanks BOD and Chris. It seems it is less straightforward a question to answer than I had originally thought.

Whilst I do not dispute at all the need to pay for the supply connection, given my earlier experience with WPD I am cautious about accepting at face value the things they say about their supply and the way the costs are divided up. 


It's really helpful to learn that the capacity of a 185mm2 cable is much less than I had thought. My assumption was that if a 95mm2 cable can feed a whole street (which it currently does), then adding a 185mm2 must provide a lot more. If they are having problems locally, then I can see how this would potentially use up a significant amount of the available capacity. 


It would be helpful to better understand why they would not consider upgrading it as a matter of course, given that they are going to pay to dig up the neighbour's garden, and I may well go back and explore that a little more. After all, they know they are going to have to expand capacity even further in the coming decade.


Have a restful evening.

M

As far as The OFGEM book of words (P16)  are concerned the term implies eventual disconnection/removal  of the original cable

Cable overlays This is an alternative expression for the replacement of an existing underground >cable with a new underground cable. The activity includes the installation of the new underground cable, the full decommissioning of the existing underground cable, any necessary underground cable jointing and any associated network operations


To minimise disruption, there is a period when both old and new are live, and then customers are transferred across, usually live working. I'm sure there will be cases where the old cable gets left in, but this probably isn't one of them.

More generally I think a lot of dicky 'Consac' cable from the 1970s is being overlaid, before the aluminium outer fails.

Hello again

Overlay normally means that a new cable is laid along the same route to replace the old cable.  Sometimes the old cable or sections of it is/are removed sometimes it isn't.


Without more information on the existing loads I really cant give you a definite answer however if the overload on the existing 95mm2 cable is so severe that virtually all of the capacity of a 185mm2 cable would be needed that implies something approach a 70% overload and I would have expected problems before now.


As a next step I would ask them what they are assuming about your new power requirements (they seem to be providing only a single phase service) and what the loadings are on the existing cable.


Another alternative would be that they overlay the 95mm2 cable but re-use it to feed your new service.  It could simply be jointed to the new 185mm2 cable at source.  That way they might even save the cost of the breeches joint at the crook of the field.


I would keep asking questions and see where you get to.