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rallyandy

I was just round a mates site today where he is wiring a new medium size warehouse which is going to distribute car parts.... i noticed their were a lot of wires hanging out of a 4 way grid switch, so i said how come their are so many wires for 4 switches, and what he had done is taken three phases from separate mcb, s at the DB to the grid switch were they connected to 3 switches to control some lighting, on the common side of the switches he had run the lighting feeds from separate rooms to these instead of back to the DB. the feeds from the DB were 2.5mm is this ok or not, i have never seen it done this way,but he says teel me where you can't in the regs as he feels it is ok due to low volt drop from the board.

good one i think
 
Nowt wrong with running lighting feeds in 2.5mm, but if he is running 3 seperate lighting circuits to a 4 gang switch then he obviously ain't done any calculations for the loading of the DB. Nothing wrong with that, I suppose if there ain't gonna be much on the DB. BUT I would suspect that that he's just trying to ensure a balanced load over the three phases. This would make me suspect that he possibly ain't up on his testing. I'd deffo keep a beady eye out on it.
 
hi ken, hes spot on with things as a rule, he says it its so he can balance loads easier and save on keep running seperate circuits from the DB as the demand is very low, ie one socket ring upstairs and one down and the lighting, he is one for over speccing rather than calculating to the nearest if you know what i mean
 
Weird but not wrong. Best put a label on tho'.
If its a warehouse why not stick the main floor lights through contactors and separate feeds to the offices. Just an idea........
 
definitely different, never seen it done that way before, as you say big n daft not wrong, the more i think about it the more it makes sense in some ways, there are 3 rows of 3 x 250w low bays on each switch and an emergency light test switch, so the demand is low so as he stated whats the point running reception and meeting room light feed back to the board
 
414V? Don't you mean 400V? Even the old calculations were done to 440V so curious to know where the 414V figure comes from.

Thanks for pointing that out. I dont even know where 414V volts came from DOH
400V it should have been.
 
Thanks for pointing that out. I dont even know where 414V volts came from DOH
400V it should have been.

A Homer Simpson moment then
Concern he not, we all have them

I get them frequently now that spring chicken is used to describe someone else not me
Typing tantrums are another one, i dont know about you but sometimes my fingers take a veiw all of their own
 
After years of 415V and 240V I still slip back now and again and then have a typo and get it wrong !!!
Mind you Dunc mentioned 440V when he corrected me and I really dont know where that came from lol
 
but do we actually notice the difference in the voltages as they have amended the tolerances but not altered the national grids output..... another Brussells interfering finger I think
 
After years of 415V and 240V I still slip back now and again and then have a typo and get it wrong !!!
Mind you Dunc mentioned 440V when he corrected me and I really dont know where that came from lol

415 & good old 240 volts @ 50 cycles per second oh happy days -- none of this 400 / 220-230v 50-60Hz that we have today and all installed to the 14th Edition which used to fit in your pocket!!
 
If Brussels had their way we’d be down to 380V (Belgian supply voltage).

That would cause far to many problems for the grid. Most voltage regulation is done at the 33/11KV transformers with automatic on load tap changers (OLTC). Industrial users would not be happy with any voltage reduction domestic users I doubt would notice.

One site I worked on the intake sub was fed at 11400V, this was reduced to 11000V by the supply company. We had to shut down every transformer and alter the off load tap changers to crank the output voltage back up to 433V or 550V.

Other sites I’ve worked on had the luxury of there own 33/11KV transformers and OLTC’s. One particular site the engineering manager would help if you wanted to find out how something worked. So one Sunday afternoon he left word for me to go and try out the voltage regulation system and see how it worked. I got radio messages from all over the works complaining when I dropped the voltage to a ¼ of the works distribution system from 11000V to 10250V. I was having fun watching the glass fronted voltage relays operating. My name was sh*t in 2 local pubs and quite a large area around. Their supplies were from the works grid. I was having fun the barmaids weren’t.
 
After years of 415V and 240V I still slip back now and again and then have a typo and get it wrong !!!
Mind you Dunc mentioned 440V when he corrected me and I really dont know where that came from lol


It's an Older Industrial voltage, it was actually 433 volts PH to PH, and 250 volts Single phase...

These so called new voltage 400V/230V bands are purely virtual, ...the 415V/240V is still the nominal voltage in the ''Real world'' It'll be years, (if ever) before you'll actually see these voltages on distribution supply TX's. ...The cost to physically change over now, will be in the Billions or even Trillions....
 
They will never change the voltages supplied they just increase the voltage tolerance band. It amazes me that they can supply a single phase supply of 216V - 253V that is quite a wide band.
 
Heres a link to an extract from the IEE on TLC's website which explains the tolerances and timelines... quite interesting but still doesn't change our voltage just the upper and lower band increased... Mad or what

wont let display link probably coz its from a company, here is a paragraph instead lol


Note on Supply Voltage Level
For many years the supply voltage for single-phase supplies in the UK has been 240V +/- 6%, giving a possible spread of voltage from 226V to 254 V. For three-phase supplies the voltage was 415 V +/- 6%, the spread being from 390 V to 440V. Most continental voltage levels have been 220/380V.
In 1988 an agreement was reached that voltage levels across Europe should be unified at 230V single phase and 400V three-phase with effect from January 1st, 1995. In both cases the tolerance levels have become -6% to +10%, giving a single-phase voltage spread of 216 V to 253 V, with three-phase values between 376V and 440 V. It is proposed that on January 1st, 2003 the tolerance levels will be widened to +/- 10%.
Since the present supply voltages in the UK lie within the acceptable spread of values, Supply Companies are not intending to reduce their voltages in the near future. This is hardly surprising, because such action would immediately reduce the energy used by consumers (and the income of the Companies) by more than 8%.
In view of the fact that there will be no change to the actual voltage applied to installations, it has been decided not to make changes to the calculations in this book. All are based on the 240/415V supply voltages which have applied for many years and will continue so to do.
In due course, it is to be expected that manufacturers will supply appliances rated at 230 V for use in the UK. When they do so, there will be problems. A 230 V linear appliance used on a 240 V supply will take 4.3% more current and will consume almost 9% more energy. A 230 V rated 3 kW immersion heater, for example, will actually provide almost 3.27kw when fed at 240 V. This means that the water will heat a little more quickly and that there is unlikely to be a serious problem other than that the life of the heater may be reduced, the level of reduction being difficult to quantify.
Life reduction is easier to specify in the case of filament lamps. A 230 V rated lamp used at 240 V will achieve only 55% of its rated life (it will fail after about 550 hours instead of the average of 1,000 hours) but will be brighter and will run much hotter, possibly leading to overheating problems in some luminaires. The starting current for large concentrations of discharge lamps will increase dramatically, especially when they are very cold. High pressure sodium and metal halide lamps will show a significant change in colour output when run at higher voltage than their rating, and rechargeable batteries in 230 V rated emergency lighting luminaires will overheat and suffer drastic life reductions when fed at 240V
There could be electrical installation problems here for the future!
 
Last edited by a moderator:
I've been against any such changes from the very start of those negotiations way back. From what i and others could make of it at that time, the IEE were being railroaded into agreeing when most of it's membership including myself were totally against it. It was and still is, a Nonsense, it doesn't work , the advantages to the very few are far outweighed by the very real dis-advantages for the many!!!!

Funny isn't it, .... the supply companies had and have no intention of lowering there supplied voltage for economical reasons, but no-one gives a monkey's that this new EU 230V rated equipment and appliances will have it's life expectancy reduced, and reduced significantly in some cases, and in many cases cost you quite a bit more to operate too!!
 
Thats very true E54, i wonder how many of us actually study the voltage labels on appliances that in depth to check whether it is 240 or 230 and just presume because its bought in the UK it must be 240, when in reality it will be 230 with now a reduced lifespan on our unchanged supply voltage. I think this is going to gather momentum when appliances start to fail quicker, will the manufacturers still honour the Warranty if it fails within the warranty period and its found to be caused by overvoltage?
 

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