DNO charges for upgrading 100A TP+N service

[vitoboy]

Hi all

An industrial customer of ours is running a laser cutting machine at a local industrial estate unit.
He has been there 15 years and has changed machines a couple of times ..but loading have always stayed the same or reduced a bit.

This week they gave me a call as they could smell something hot near the DB .. as it happened it was the cutout that was very hot .. and the customers DB gear on;y slightly warm as is usual .. meter not really hot either.

Called the DNO and they promptly changed the cutout .. while unknown to me the new cut out came with 80A fuses not 100A as had been previously installed.

2 days later i got another call .. 1 phase has gone down .. seems that the 80A fuse was not up to the job.. so called the DNO and asked for 100A fuses to be reinstalled.

First they clamed that the original fuses were 80A .. no they were 100A and seen to be so when the cutout was changed.
Then they clamed that the system was overloaded and would need to be upgraded ... well its been ok for 15 years and in that time we have actually reduced the load quite a bit .. and never had a problem before.

Now they have agreed to reinstate the 100A fuses for now ..but insist on fitting a meter to check the load to see if the customer will need to pay for a supply upgrade.

I can see how this would be good for them .. but im unsure if they can really force this to be done and charged to the customer.
I cant seem to find anything about this on the net ..and the DNO advice seems very one sided at the moment.

Can anyone point me in the right direction for more info here or give me some guidance i can pass on to the customer.

Cheers

Vitoboy

 

[DPG]

Sounds like maybe the fuses had been running over capacity for some time, but not enough to rupture? Can you clamp each phase when the unit is pulling maximum power?

 

[UNG]

I think you need a power analyser connecting to the supply for a week or so to work out what the actual maximum demand is and what peak usage is throughout the day, it sounds like the supply is at the point where it is right on the edge and even a small additional load could tip it over the edge. If the supply does need upgrading it may be more prudent to look at a larger supply than the 100A to give a bit more margin for future expansion

 

[vitoboy]

Yes I can clamp meter it.. but I believe the total load is not more than 100A per phase anyway..
I believe the issue is that the supply is running at 80 - 95%% capacity for 10 to 12 hours a day on busy weeks .. but not over 100A a phase.
I also believe that the issue here has been thermal damage over 15 years to the cutout .. but the customer has a 100A switched fuse with bolt on fuses .. and no thermal damage has been seen on these nor have they caused an issue in 15 years...
At the moment I'm more interested in what the DNO can legally charge for / force to happen .. like upgrading the supply.
Generally the DNO these days like for customers to pay to upgrade their systems.. and im not happy that my customer should be paying for an upgrade for this system.
I'm also wondering why I can't find an easy answer to my questions on the Web.. or from the DNO . .
. who have already been shown to be un trustworthy by telling porkies about the original supply fuses and immediate call to pay for a supply upgrade on something that's been fine for 15 years.

Ta for your reply DPG

 

[snowhead]

If the original supply agreement was for 80amp and the DNO can produce a copy I suspect they will want the customer to pay for an upgrade.
If the 80 - 95% usage is above the agreed or above their normal terms then whether the agreement is for 80 or 100amp the DNO will want the supply upgrading.

At some point if no agreement is reached on an upgrade then I suspect the DNO will refit the 80amp fuses and bill for any attendance and for the replacement fuses each time.

I'd be carefull about causing too much of a fuss as they could go down the route of wanting to check if the Laser cutter is introducing harmonics to the supply and if so they may either want measures put in place to supress them or could insist the equipment be disconnected if they believe damage or disturbance to other local customers could occour.

I don't beleive the DNO's are obliged to supply a property, so could refuse to supply altogether

 

[UNG]

Yes I can clamp meter it..but I believe the total load is not more than 100A per phase anyway..

How much time are you going to spend monitoring a clamp ammeter. I would suggest as in my previous post that you install a power quality analyser for a week or two that will take readings every few minutes and the software will put it all into a graph so you can see when the peak load occurs

I believe the issue is that the supply is running at 80 - 95%% capacity for 10 to 12 hours a day on busy weeks .. but not over 100A a phase.
I also believe that the issue here has been thermal damage over 15 years to the cutout .. but the customer has a 100A switched fuse with bolt on fuses .. and no thermal damage has been seen on these nor have they caused an issue in 15 years...

So is the 80 - 95% taking any account of any inrush currents when equipment is switched on, at 95% there is not much overhead to the 100A fuses, any thermal damage at the cut out could be down to an overload on your customers part as we all known the constant heating and cooling of load carrying parts can and does result in a loosening of connections over time, with regard to the customers switched fuse in a lot of cases they are over engineered and may of had PPM work carried out over the years to ensure the connections had not become loose so it is difficult to use that as a comparison

At the moment I'm more interested in what the DNO can legally charge for / force to happen .. like upgrading the supply.
Generally the DNO these days like for customers to pay to upgrade their systems.. and im not happy that my customer should be paying for an upgrade for this system.

The DNO has never in the 40 odd years I have dealt with them upgraded a supply for free so charging is not a recent thing

I'm also wondering why I can't find an easy answer to my questions on the Web.. or from the DNO . .
. who have already been shown to be un trustworthy by telling porkies about the original supply fuses and immediate call to pay for a supply upgrade on something that's been fine for 15 years.

I suppose it depends what your questions are
With regard to the porkies their records may indicate a supply fused at 80A and after a visit from less than scrupulous seal fairy and hey presto some 100A fuses have been fitted and yes I know sites where it's been done
By your own admission it obviously hasn't been fine for all of the 15 years as failure of a cut out isn't an instant failure that happens
You and your customer are trying to run on the absolute limit of the supply at times and by the sounds of it in the past it has been exceeded
IMO you are picking a fight with the wrong people when trying to force the DNO's hand

 

[plugsandsparks]

I would have thought the DNO would suggest a load reduction, rather than supply upgrade. This can be achieved relatively easily compared to the cost of a supply upgrade above 100A.

As mentioned, general process is to monitor current and PF over a good period. Look at loads that can be reduced , like lighting, look at PF and if the high currents are at say 0.9 or lower, then a simple PFC will bring the current down.

Good luck

P&S

 

[vitoboy]

Thanks p&s