Mains Voltage

any load.

You are due for a replacement street/house transformer.

My old setup did this. The microwave caused every light to dim. Transformer on a pole. Yuk.

When I finally undergrounded the supply I gort a huge steel cabinet in the garden corner. Problems solved., I have my own 100KVA substation :-)

Contact the electricity company. They are supposed to be duty bound to fix this for you.

Reply to
The Natural Philosopher
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Those transformers were out up when at most a house would draw 3KW, and they are crap, old fashioned, use rubbish cores and you need a better one.

With luck, they may underground your supply as well, if ou suggest it to them.

Reply to
The Natural Philosopher

Just the transformner, as when mine got replaced, all problems vanished.

>
Reply to
The Natural Philosopher

The 11KV will be OK. We are miles down one branch. Its fine. The transformer will not be.

Reply to
The Natural Philosopher

Being able to deliver the juice with little drop, and being able to deliver it without going bang, are two different things.

You cam easily dissipate 5KW or more from a pole mounted transformer without it going bang...

Modern ones may be better, but the one that came off my pole was circa

1948 vintage and total utter crap at anything over a few amps.

I know it wasn't the 11KV, because a new substation completely fixed it.

And an 11KV line that sags because *one* person puts a few KVA on it is absolute balls. Its rated for ALL the people on it and maybe if they ALL switched on their tellies you might see a sag, but not just one sodding person.

There is only one thing that fits the bill. The transformer, or connections to it. In short the problem is between the 11KV line and the consumer unit.

Apart from bits of wire, there is only the pole mounted transformer, and my experience of those is that they are useless if more than 20 years old.

In my case they were only to happy to get rid of it and have me bear part of the cost of a bit of undergrounding I suggest the OP uses this as a lever..to get the lot buried at little or no expense.

More to the point how many other people are on it?

If more than two it ain't the problem. Otherwise half a dozen people putting an electric fire on would dive it into the ground, at that implied impedance.

Reply to
The Natural Philosopher

AFAIR, I thought that FiL made a mistake in using the words 'motor mechanic', 'welding', and 'flickering lights'. The electricity Co were not interested in replacing the transformer. I suppose an intermittant load, such as welding, would not generate enough revenue to cover the cost of installing an uprated transformer.

The OP does have a case here though because the voltage is below 230 -6% with only a 12KW load.

It would be useful for him to check the voltage when both houses are taking no load. Anywhere near 250V would be ammunition to argue *against* their simple getout of tapping up.

Reply to
Tony Williams

Just two of us on the 11kv line. About 500 yards up the lane there is another group of houses and a pub, they have a transformer also. There are three 11kv wires to that. (so that would be 3 phase) After that the three phase 11kv wanders off across fields and I loose it from sight. Maybe Google earth would be helpful.

Anyway, A friend of a friend once worked as an engineer for MANWEB. He's hopefully going to chat with me tomorrow on the best tactics regarding getting an upgrade. It does sound to me like a geriatric transformer problem.

Thanks for the help chaps, I've got plenty of ammo now!

Julian.

Reply to
Julian

Oh so you have a two phase spur off the main 3 phase and 500 yards of that to just the one transformer?

Hmm. Its about 30 grand a kilometer to underground..

Id say that 500 myards of spur is not goi ng to sag..lets face it its less than an amp to give you 11KW...and to get a 20% V drop on that would mean a 2KV drop..around 2Kohms...iI cannot see 500 yards of cable being that high unless its about to fall apart..

Sadly I think its get the power company in, and they will just replace the overhead transformer..

99.9% certain, yes. They don;t do new overhead installations anyway, which dates yours to probably no later than 1960 or so.

Oh, you have a cast iron case. That's probably why its sagging. These days they use silicon iron laminations ;-) ;-)

The supply is out spec, and they HAVE to fix it.

Reply to
The Natural Philosopher

Those pole transformers don't have taps.

I dunno if better ones are available..as I said. mostly they prefer to underground in the case of any serious faults wherever possible.

Even 11KV overheads are not being built..too much maintenance in the gales.

Reply to
The Natural Philosopher

Seen this problem out a a number of comms sites out in the sticks.

Almost invariably an underrated transformer for today's loads. Grumble and kick up a fuss and get the tranny uprated!...

Reply to
tony sayer

Possibly, however you can't rely on getting the same readings each day since it is not only your property providing the load.

The true RMS nature of the meter may have had an impact if you have a reasonable amount of load that is not at a unity power factor.

TN-C-S and PME usually.

The situation was probably worse than your figures initially suggest since I guess you were assessing the load by reading the power consumption off the spec plate on the equipment. Since you were not actually feeding the specified voltage, the actual power drawn by the resistive load will have been below spec. So 214V at 11kW is probably more likely.

If you have access to a clamp meter that you could stick round one of the meter tails then that would give you much more accurate information regarding the actual current load.

Yes you do have a case for complaint. There is no need to mention the welding requirement as such, but just commenting on dim lights, and other electrical goods not functioning as they should - especially early evening etc ought to be enough.

(A friend had a similar problem in that his garage door opener would not work in the evening when the supply fell to 200V. Another friend recently got compensation for a new freezer after a couple of days of persistently low volts at his premises pushed it over the edge (although that was down to 100V on occasion))

You would need to point out the big swing in voltage - there is a good chance you could be close to the upper limit with no load (including the neighbours).

Reply to
John Rumm

I wouldn't expect the cable to have anything like that resistance. It's a hefty bit of copper up there. They replaced and/or upgraded the 11kV line up the otherside of the valley that feeds the village the other year. I was surprised at the 1/2 dia copper they where putting up...

But a few iffy connections or just one a bit high and you can loose the regulation. The board need to come out and investigate. it could be an underated transformer (but why has it only just come to light?) or any number of poor joints from the CU to the 33kV substation upstream.

Reply to
Dave Liquorice

Yes, I understand that, but I had the two meters running together for comparison.

That's true, I never thought of that. Yes I just looked at the rating labels (fan heaters and kettles)

My mate's got one of those, I'll borrow it soonest.

I'm on the blower to them tomorrow. I've been chatting with my neighbours, and they have noticed dimming lights when I weld - so the problem is common to both our installations. Next door are nice people, they're not bothered by my welding because it is infrequent and we do favours for each other, and they are prepared to complain too to help my case.

Julian.

Reply to
Julian

suggest since

consumption off

feeding the

rating labels

information

neighbours,

So you need to talk in terms of lights flickering as the 'fridge starts up and when you put the kettle on, and going really dim with the electric cooker, and your electronic alarm clock keeps resetting and you're worried if perhaps there is a safety issue - and perhaps sound a little panicky (and should all that snow have melted SO quickly arround their transformer last winter)

AWEM

Reply to
Andrew Mawson

As Andy mentioned in another post, there is a potentially serious safety issue here.

All the circuits in your house will be protected by overcurrent devices which you expect to open fast enough to clear a fault should one occur, and without the wiring in the house suffering damage as a result. With a much lower than expected voltage, you can no longer rely on this being the case since you are outside the design parameters of the circuit and cable, and it will take longer than expected to open the protective device.

The problem is compounded if you have a supply with Neutral and Earth combined at the origin of the installation. Your high supply impedance will also translate into a high earth fault loop impedance. Which in turn could leave metal work rendered live due to a fault, in that state for much longer than expected (assuming the circuit is no RCD protected).

If you refer to appendix 2 of the on site guide, this lists the maximum allowable impedances for different protective devices. Note that this is the impedance measured at the far extent of the circuit in the property, not at the CU, and hence includes the loop impedance of the house wiring as well as that of the supply.

For example a 30A rewireable fuse is only safe with impedances up to

0.91 ohms. A type B 32A MCB 1.2 ohms
Reply to
John Rumm

A very rough rule of thumb is that a HV feed is good for

1 mile per kV, i.e. 11 miles for 11kV feed. Of course, there are many other influencing parameters too.
Reply to
Andrew Gabriel

its not all copper..its wound round a steel core for strength..there is a relationship between span and how fat a cable has to be to not sag and touch the ground..or an adjacent conductor..they pick that size of steel and wind what copper they need over the top.

No, it can't be. It can only be in the section that is private to you, or your load would not be able to have the impact it has without the whole local area going down in darkness every time people switched on 'big brother'

Its a bad connection to YOUR transformer, YOUR spur or a bad transformer.

Reply to
The Natural Philosopher

I think most pole mounted transformers simply have an earth strap running down the pole..connected to neutral ..and a local earth spike.

Reply to
The Natural Philosopher

Oh yes they do.

Reply to
The Wanderer

Having read all through this thread, you've had an assortment of half-truths, some red herrings, and in one or two instances total rubbish.

Your transformer looks as though it may be a 15kva rating. It's not a shape I immediately recognise, but from what you've said it seems like it's been there for quite a while. As someone else mentioned, it was typical of what was installed when most places had just a couple of lights and a plug. It doesn't look to have been cooked unduly, pole transformers can discolour quite badly if they're subjected to sustained overloads, and as an aside, the insulating oil inside the transformer turns quite acidic.

The 11kv o/h line is very unlikely to be the problem, unless there's a dodgy joint somewhere. The industry went through a phase (if you'll pardon the pun) of using aluminium conductors for two or three decades. There can be - but may not actually be - a problem if there are poorly made bimetal joints out on the system.

You also appear to have a two-wire lv system from the pole to the properties, probably splitting where it terminates on the building.

Whatever readings you are getting, either using your own of your mate's Fluke meter are an indication, and only an indication. They are good enough to make your case that you have problems. I used to carry a laboratory sub-standard, regularly calibrated. That was the meter I'd believe. It could indicate a difference of several volts in the readings to other meters!

You seem to have two quite separate problems, very poor regulation, due to an overloaded transformer and almost certainly caused by load growth with you and your neighbour. You are also using a welder, which is a dirty load, and may require a larger transformer than to meet a resistive load. You haven't mentioned anywhere about the rating of the welder, which is relevant.

Firstly, you need to complain to your local distribution company that you and your neighbour are noticing significant dips on the lights, that, after all is how most people first become aware that they've got a problem. Make sure they realise you are both experiencing problems.

Tell them that you've carried out some simple checks, and give them the voltages you've measured for different loads. Make sure they realise that you know the voltage shouldn't drop as much as it is for what is a normal load these days. If you think you're getting the run-around from a call centre monkey ask to speak to an engineer who deals with these types of complaints.

They will almost certainly come and instal some sort of recording voltmeter as an initial move. This will give an indication of how the voltage varies with time of day. Whether or not you tell them about the welder is, of course, up to you. If you choose not to, don't be surprised if they carry out remedial works and you still find you've got problems. See my comments above!

Freom your POV, I would also be looking to get separate cables installed from the transformer to each property.

Reply to
The Wanderer

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