Main incoming cable 10mm

[JohnW2]

Sadly very few do read terms and conditions. ... And maybe on the electricity bills a reminder. If the modern electronic meters can record peak current levels then if ( when ) there is a prolonged usage at or above the contracted supply maximum the meter could inform the billing department who then add the caution to the bill. "your consumption exceeded agreed maximum supply, please seek advice".

...which brings me back to the point I have been making. If my contract with my electricity supplier, or even their T&C, actually defined what you call the "agreed maximum supply", then your proposal would make sense. The fact is that, unless I'm missing something, there is nothing specified, let alone 'agreed', in my contract (or the T&C) about the level of the 'maximum supply'. That being the case, a 'caution' such as you suggest really would be akin to issuing a driver with a caution for exceeding a speed limit, the level of which had not been indicated!

That could obviously be remedied easily, but I would doubt that 'peak current' would be an appropriate basis for defining the maximum. Everything about electricity supply, whether within one home or much more widely, is probabilistic (i.e. about 'averaging' - 'diversity', if you wish). Most 'ordinary' homes, with perfectly 'ordinary' loads, have the potential to occasionally draw very high currents for brief periods (you've only got to add up the MCB ratings in a CU to see that!), purely by chance - e.g. it's not totally impossible that, by pure chance, a shower, kettle, toaster, cooker, washing machine, tumble dryer, hair dryer and immersion heater, and maybe even a fan heater or two etc.etc. could all be drawing their maximum possible currents simultaneously for a brief period of time. Extreme cases like that will be rare, and it's extremely unlikley that the same would happen simutaneously in a number of nearby properties, so there is unlikely to be a significant impact on the network. I would therefore think that any definition of the "maximum agreed supply" should relate to the load averaged over some time period (30 minutes, 1 hour, half-a-day,or whatever). The absolute maximum sustained load is, of course, already defined by the DNO's service fuse.

Whatever, no matter how they choose to define the "maximum agreed supply", it clearly should be stated! One suspects that their apparent reticence to do this may result from them fearing that it might be taken to indicate a binding obligation on their part to always make that "agreed maximum" available to all customers (no matter how extreme the circumstances) - but I'm sure they could find some small print to get them off that hook!

Kind Regards, John

 

[westie101]

which brings me back to the point I have been making. If my contract with my electricity supplier, or even their T&C, actually defined what you call the "agreed maximum supply", then your proposal would make sense. The fact is that, unless I'm missing something, there is nothing specified, let alone 'agreed', in my contract (or the T&C) about the level of the 'maximum supply'. That being the case, a 'caution' such as you suggest really would be akin to issuing a driver with a caution for exceeding a speed limit, the level of which had not been indicated!

That could obviously be remedied easily, but I would doubt that 'peak current' would be an appropriate basis for defining the maximum. Everything about electricity supply, whether within one home or much more widely, is probabilistic (i.e. about 'averaging' - 'diversity', if you wish). Most 'ordinary' homes, with perfectly 'ordinary' loads, have the potential to occasionally draw very high currents for brief periods (you've only got to add up the MCB ratings in a CU to see that!), purely by chance - e.g. it's not totally impossible that, by pure chance, a shower, kettle, toaster, cooker, washing machine, tumble dryer, hair dryer and immersion heater, and maybe even a fan heater or two etc.etc. could all be drawing their maximum possible currents simultaneously for a brief period of time. Extreme cases like that will be rare, and it's extremely unlikley that the same would happen simutaneously in a number of nearby properties, so there is unlikely to be a significant impact on the network. I would therefore think that any definition of the "maximum agreed supply" should relate to the load averaged over some time period (30 minutes, 1 hour, half-a-day,or whatever). The absolute maximum sustained load is, of course, already defined by the DNO's service fuse.

Whatever, no matter how they choose to define the "maximum agreed supply", it clearly should be stated! One suspects that their apparent reticence to do this may result from them fearing that it might be taken to indicate a binding obligation on their part to always make that "agreed maximum" available to all customers (no matter how extreme the circumstances) - but I'm sure they could find some small print to get them off that hook!

I strongly suggest that you look up the meaning of the word diversity as applied to electrical installations and electrical networks!
I've already commented on ADMD.

Bear in mind also the concept of fusing factors, the factor for a 100A cut-out fuse is 1.47, i.e. it can carry 147A fairly continuously! The cut-out is rated to about 126A as is a modern service cable.
So which maximum should we use?

We state the max DEMAND can be 23kW, and know that diversity will ensure that networks are not overloaded (as long as customers don't keep adding loads we don't know about)(is it much different from a customer wanting to operate a washing machine, a tumble dryer and a dis washer from a 32A ring main?)

As for the 2kW fan heaters, it is usual for the Gas companies to hand these out to customers where gas supplies are interrupted for a prolonged time. We had a 750kVA transformer burn out through overload following such an incident! All 300 houses on an estate were using multiple ones simultaneously as well as electrical rings to cook food! Guess what the network was not designed to supply this load as there was no diversity in use!

 

[JohnW2]

I strongly suggest that you look up the meaning of the word diversity as applied to electrical installations and electrical networks!

I know what it means - and I still stand by all I said about the probabilistic nature of electricity networks and installations.

Bear in mind also the concept of fusing factors, the factor for a 100A cut-out fuse is 1.47, i.e. it can carry 147A fairly continuously!

I also know that - but what is your point? All I said was that it (obvioulsy) defines an absolute maximum sustained load - which it does.

We state the max DEMAND can be 23kW ....

Where is that 'stated'? - as I've been saying, my main problem is that I can find no mention of any sort of 'maximum' figure in the paperwork associated with my electrical installation. ...and, wherever it is stated, does it also define exactly what it means by 'demand' (i.e. literally the maximum instantaneous load,or what)?

Kind Regards, John

 

[DetlefSchmitz]

This is probably a different meaning of 'state' this time. If you are lucky enough to have a 100A fuse then the limit is 100A x 230V = 23 kW.

 

[westie101]

With it not being stated anywhere could suggest that you need to talk to the DNO before connecting any large loads!!

This is turning into a silly hamster wheel mainly because folk don't seem to like being told that there are "rules" to follow

I'm out of this one!

 

[JohnW2]

This is probably a different meaning of 'state' this time.

I suspect so!

If you are lucky enough to have a 100A fuse then the limit is 100A x 230V = 23 kW.

In terms of the 'innocent' comment I made, I was actually thinking of the true 'absolute maximum' which would be imposed by the fuse - which, as westie said, would be 147A or more for a 100A fuse. - however, what you say might indeed explain where this ('stated') 23kW maximum comes from.

Kind Regards, John

 

[JohnW2]

With it not being stated anywhere could suggest that you need to talk to the DNO before connecting any large loads!! ... This is turning into a silly hamster wheel mainly because folk don't seem to like being told that there are "rules" to follow!

... but seemingly 'unwritten rules', which is the basis of my concern.

If my electricity supplier wish to limit the amount of electricity I may use, that's totally reasonable - but why on earth do they not (unless I'm missing it) state a figure for this maximum in my contract with them or, at least, their T&C?

Kind Regards, John

 

[DetlefSchmitz]

... folk don't seem to like being told that there are "rules" to follow...

If a rule is specifically stated then I'm sure people would be prepared to follow it. If the rule is along the lines of 'some things you might do may not please us so we may cut you off, but we won't tell you exactly what those rules are' would appear to come under the 'unfair terms and conditions' area.

Ed: Sorry John, didn't see your post when I wrote that.

 

[TheKeymeister]

With it not being stated anywhere could suggest that you need to talk to the DNO before connecting any large loads!! ... This is turning into a silly hamster wheel mainly because folk don't seem to like being told that there are "rules" to follow!

... but seemingly 'unwritten rules', which is the basis of my concern.

If my electricity supplier wish to limit the amount of electricity I may use, that's totally reasonable - but why on earth do they not (unless I'm missing it) state a figure for this maximum in my contract with them or, at least, their T&C?

Kind Regards, John

Probably because of the number of variables in it!

Size of transformer, size of main in the street or overhead line, number of people on that cable, distance from transformer, size of service cable, etc, etc, etc.

In my opinion there couldn't be a single defined 'limit' for everyone because the characteristics of distribution networks are too different even from street to street.

 

[JohnW2]

If my electricity supplier wish to limit the amount of electricity I may use, that's totally reasonable - but why on earth do they not (unless I'm missing it) state a figure for this maximum in my contract with them or, at least, their T&C?

Probably because of the number of variables in it! ... Size of transformer, size of main in the street or overhead line, number of people on that cable, distance from transformer, size of service cable, etc, etc, etc. ... In my opinion there couldn't be a single defined 'limit' for everyone because the characteristics of distribution networks are too different even from street to street.

Who says there has to be a 'single defined maximum for everyone'? My contract with the supplier is unique to me, and it would be the simplest thing in the world for it to state the maximum for my supply. I really am finding it hard to understand what some people are saying about this - if a contracted supplier (of goods, services, electricity or anything else) wishes to impose a limit the amount I can be supplied with under the contract, then surely they have to tell me what that limit is? ... just as, if one imposes a speed limit, one indicates what the limit is!!

Indeed, if it's the case that my limit might be different from someone else's, then that's surely an even stronger argument for their telling me what my limit is - otherwise how on earth can I know whether I am complying with the 'rule'.

Kind Regards, John

 

[DetlefSchmitz]

Of course it is difficult. It is clearly impossible to deal with a randomly varying load, in a logical way except to either provide enough capability that the system very rarely is compromised, or to accept a certain proportion of down time caused by failures. And exceptional circumstances like the local gas supply shutting down are a significant difficulty.

But the thrust of the argument has been that this is the individual consumer's problem, and if the DNO can't cope then they are entitled to arbitrarily penalise an individual consumer who they deem to have been the camel's straw, even though they couldn't specify in the first place in advance exactly what the transgression might be.

 

[johno12345]

when i blew my supply fuse, they came and fitted a bigger one and commented that i now had an extra 70 amps to play with. I asked the DNO on the phone and they said I have a 100 amp supply and can use 100 amps.

 

[bernardgreen]

from page 8 of

http://www.westernpower.co.uk/Docum...Electricity-Supply/New-Supply-GuideAug12.aspx

● Electrical Loading
The normal maximum capacity for individual domestic properties is 15kW.
Should you require a greater capacity, please enter the capacity here: ............. kW
To help you plan for your connection, please indicate below the fuel types to be used:
Space Heating:
Gas Electric (Storage & Direct) Electric Boiler
Ground/Air Source Heat Pump Other fuel
For electric storage heating, total off-peak load is: ............... kW
For electric direct heating, total load is: ............... kW
For electric boilers and heat pumps, please include manufacturer's specification sheet.
Water Heating:
Gas Electric (Storage & Direct) Electric Boiler
Ground/Air Source Heat Pump Other fuel
Number of Instantaneous Showers and size: .............. kW each
Should you require your connection

Where the system falls down is when the property is sold the enduring constraints of the contract to install a connection to the electricity network are seldom passed over to the new owner.

 

[JohnW2]

from page 8 of http://www.westernpower.co.uk/Docum...Electricity-Supply/New-Supply-GuideAug12.aspx
● Electrical Loading
The normal maximum capacity for individual domestic properties is 15kW.
Should you require a greater capacity, please enter the capacity here: ............. kW

In the absence of any guidance in the form or leaflet, how would (or did) you interpret "maximum capacity"? Did you take it to mean the highest envisaged possible intantaneous load on the installation? If so, then for any dwelling with a reasonable-sized electric shower, 15kW would clearly be lamentably inadequate. In fact, if calculated on that basis (highest envisaged possible instantaneous load), I would imagine that the truthful answer for many 'ordinary' homes would probably be of the order of 100A / 23kW, perhpas a lot more (if they had a decent sized shower).

I wonder what would happen if one answered truthfully on that basis, and said something like 22kW. In terms of the actual 'installing', it ought not to make any difference, since I imagine that any new supply installed today would have cable and cutout rated for at least 100A - but would such a statement/request have any other 'consequences' (e.g.financial!)?

Kind Regards, John