When did we have 250 volt?

[ericmark]

When trying to explain star point I calculated how we get 400v and and 230v from same supply as a demo.
Then to show where 415v came from I did same with 240v and then realised if I did same with 250v I got 440v
I have seen many places marked up as 440v but I have not seen anywhere marked as 250v
So just as not so long ago we dropped from 240 to 230 did we also at sometime drop from 250 to 240?
The oldest item with voltage marked on it I have is an old wolf cub drill this has 240 marked on it I think around 1960's so I would think so what was the voltage pre-war.
When I first started late 1960's we were still sticking on labels on 3 phase supplies saying Danger 440 Volt but of course we all know even today we sometimes get nearly 250 volt on a meter and I had just not thought about why we slowly started to used Danger 415 Volt labels.
I know as a lad some places still had 110 volt DC supply so the 440 volt may be pre national grid?

 

[mattylad]

I was always led to believe that we had 240v as std but sometimes went up to 250v.

 

[JohnD]

before and during WW2, different towns and regions had their own standards, and their own Electricity Boards. Some were on 250v, some on 240, 220, some even 110

IIRC the National Grid was only operational after the war, and the CEGB set up, After this, all but the most isolated communities were brought to a national standard. Funnily enough, the "Standard" had such wide permitted variations that almost all of the local supplies could be described as meeting it, even before they were changed.

Incidentally, there were also different local standards for plugs and sockets. The square-pin "13 Amp Plug" was brought in to standardise, and was (in the 1940's) a great leap forward.

 

[ericmark]

Thank you so the 440 Volt Danger signs were really old? I worked for SLD Pumps back in 1979 and we were still using them then. I expect we will still have things marked 415 volt in 10 years time. Every one seems to get into idea of 230 volt but not 400 volt for some reason. May be because in reality we still have 415 volt?

 

[Fred_Fanackapan]

I remember being on 210v in the 50s. The electricity board gave use new light 'bulbs' when they changed to 240v.

 

[securespark]

We're still on 250V...Well, 216-252V to be precise!

 

[rjuk]

Just checked our mains voltage to find 253V.

No wonder we get through plenty of bulbs.

 

[kevindgas]

regularly find 248 to 252 volts round poole and bournemouth in southampton it usually 240 -245 ish

 

[Click-Sure]

I got dead-on 230v at a house I was working in today. Thats rare, I thought to myself.

 

[ericmark]

I do agree in reality we still have 240/250 volt and over the years I have had far more problems with equipment not working with under voltage than over voltage except for bulbs. So I can see why they air on high side.

Florescent light fitting are worst. Under voltage they fail so we complain but over voltage they seem to work without a problem until you clip on the ammeter and see a 60W fitting instead of taking 0.26A is taking 0.45A each.

First time I had problem was Sizewell B which was being built right next to the A station and when the A station was on line our voltage went up.

I was told to light some tunnels with 110V florescent lights all 60 watt quick thought was should be able to get around 32 as just over 0.5A each so we would go for 25 on each 16A MCB it would give us some lea way. After fitting they tripped measured and 25A draw no wonder they tripped so did some tests. Lucky the units included an auto transformer with 110V and 127V input option re-set them all at 127V and last few did not fire up so did first 20 at 127V and last 5 at 110V and all ran without problems total draw 15A.

After that I have measured many times and found similar over current use and am a great believer in the HF ballast as a result.

Problem now is the CFU as most have no details on the side and some are HF units and not too worried about voltage and some are not and if bought from a retail outlet try taking one back and saying this does not work in my house. Especially when they plug it in works A1 in shop.

 

[JohnD]

just checked mine and it is 238v

 

[Stoday]

The standard declared voltage is 230V +10% -6%.

That does NOT mean that the average voltage is 230V. On the contrary, on average it would be 240V to 250V.

To minimise the cost of lines and cables, the Distribution Network Operator would design an LV network so that it is fed with 250V at the substation. Houses near to the sub will always get 250V. Houses at the far end will get 216V only on days and times of peak demand - around 5.30 p.m. in January. So most of the time even these will get more than 230V.

Electricians will never see the low voltages because they've bu99ered off to the pub by the early evening.

 

[ericmark]

The standard declared voltage is 230V +10% -6%.

That does NOT mean that the average voltage is 230V. On the contrary, on average it would be 240V to 250V.

To minimise the cost of lines and cables, the Distribution Network Operator would design an LV network so that it is fed with 250V at the substation. Houses near to the sub will always get 250V. Houses at the far end will get 216V only on days and times of peak demand - around 5.30 p.m. in January. So most of the time even these will get more than 230V.

Electricians will never see the low voltages because they've bu99ered off to the pub by the early evening.

We are referring to "Nominal Voltage" which changed on 1st Jan 1995 from 240 to 230.
I know in real terms the maximum voltage only dropped 1.4V due to permitted tolerance change so we have 204.7 to 253 volts at socket outlets.
But when I was first an electrician all domestic type outlets were labelled as 240 but the three phase supplies were labelled 440 which does not match.
I asked my father-in-law and he does not remember the voltage ever being officially changed.
I can remember when I was around 10 years old the remnants in the outlying villages being put on the National Grid although it was only last year that the last village somewhere near Bala when on National Grid but most I think Nation grid was started 1919 and in the main completed in 1948 about 3 years before I was born.
And even today there are still some odd voltages where Ulster I believe use 10Kv for distribution where rest of UK uses 11Kv and of course many large companies have been supplied with HV and it is transformed on the premises where required so they could select any voltage they wanted.
In Hong Kong we had transformers to drop the voltage from 11kv to 10kv at which voltage it was transported to our machine which then further reduced to voltage to 660V which feed the main motors but the auxiliaries had another transformer supplying 220V on a delta output using the IT distribution system.
Mines and quarries have always seemed to use a higher voltage.
So maybe companies would use 440 volt with the big machines near to the transformer and the offices would be some distance away and by time it got there it was 240V due to volt drop in the lines.
Maybe we never did as a nation have 250 Nominal Voltage but the 440 was private supplies into factories from there own transformers?

 

[Stoday]

There were a lot of odd supplies around the country prior to the early 1960's, a consequence of many small towns having their electricity supplied from a local large factory/mine rather than the local electricity board.

I particularly remember that the town of Staveley was supplied from a Staveley Industries factory up to the mid 1960's. I can't remember the voltage, but the frequency was 30Hz.